Are you over 18 and want to see adult content?
More Annotations
![Tamada, DJs, Saxophonisten, Hochzeitssänger und Hochzeitsband Big Bada Boom Show Agency](https://www.archivebay.com/archive/7853455a-0175-469e-bed5-f63703b0cf2b.png)
Tamada, DJs, Saxophonisten, Hochzeitssänger und Hochzeitsband Big Bada Boom Show Agency
Are you over 18 and want to see adult content?
![Электротранспорт - Главная страница](https://www.archivebay.com/archive/b36115e9-8d49-43a9-a432-6a35cb231096.png)
Электротранспорт - Главная страница
Are you over 18 and want to see adult content?
![A complete backup of the-burnout-pad.myshopify.com](https://www.archivebay.com/archive/52cb2704-a100-4289-9079-d90b39a28f91.png)
A complete backup of the-burnout-pad.myshopify.com
Are you over 18 and want to see adult content?
![in der Familie – Unsere techPulse120 Familie](https://www.archivebay.com/archive/60d705bb-868c-4552-a2eb-3e126461123b.png)
in der Familie – Unsere techPulse120 Familie
Are you over 18 and want to see adult content?
![Tobias van Schneider - Design & Creative Direction](https://www.archivebay.com/archive/46390ba8-7c7d-4f00-ab21-97be0f4cd347.png)
Tobias van Schneider - Design & Creative Direction
Are you over 18 and want to see adult content?
Favourite Annotations
![A complete backup of albinoblacksheep.com](https://www.archivebay.com/archive2/a4632026-baae-4015-89e6-d64f94904b1c.png)
A complete backup of albinoblacksheep.com
Are you over 18 and want to see adult content?
![A complete backup of forzabvb.tumblr.com](https://www.archivebay.com/archive2/d47a5f59-68b8-4146-9ffc-a1d72922c678.png)
A complete backup of forzabvb.tumblr.com
Are you over 18 and want to see adult content?
![A complete backup of lipotherapeia.com](https://www.archivebay.com/archive2/7f074983-c2b6-4e64-ab42-71b7a35724f0.png)
A complete backup of lipotherapeia.com
Are you over 18 and want to see adult content?
Text
new.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clearFOUCAULT TEST
4.8.2. Foucault test. Invented by the French scientist Leon Foucault in 1858, this ingenious test uses point source of light placed at the center of curvature of a concave mirror (in practice, slightly to the side, so that the mirror focus is separated from the source, and TELESCOPE ASTIGMATISM Telescope astigmatism. Similarly to coma, astigmatism is an off-axis point wavefront aberration, caused by obliquity of the incident wavefront relative to the optical surface. Astigmatism results simply from the projectional asymmetry arising from wavefront's inclination to the optical surface. The diameter of wavefront's projection ontothe
NEWTONIAN TELESCOPE COLLIMATION in radians, with a being, as before, the diagonal's semi-axis, f the mirror focal length, H the focus-to-diagonal axial separation, and A the diagonal's minor axis, A=2a (if we designate the diagonal-to-primary separation as S, it simplifies to δ =a 2 /HS= A 2 /4HS). For the above 300mm f /5 Newtonian, it would come to 0.0039, or0.22 degrees.
HINDLE SPHERE TEST
FIGURE 56: The Hindle sphere test setup: light source is at the far focus (FF) of the convex surface of the radius of curvature R C and eccentricity ε, and Hindle sphere center of curvature coincides with its near focus (NF).Far focus is at a distance A=R C /(1-ε) from convex surface, and the radius of curvature (R S) of the Hindle sphere is a sum of the mirror separation and near focus (NF AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clearFOUCAULT TEST
4.8.2. Foucault test. Invented by the French scientist Leon Foucault in 1858, this ingenious test uses point source of light placed at the center of curvature of a concave mirror (in practice, slightly to the side, so that the mirror focus is separated from the source, and TELESCOPE ASTIGMATISM Telescope astigmatism. Similarly to coma, astigmatism is an off-axis point wavefront aberration, caused by obliquity of the incident wavefront relative to the optical surface. Astigmatism results simply from the projectional asymmetry arising from wavefront's inclination to the optical surface. The diameter of wavefront's projection ontothe
NEWTONIAN TELESCOPE COLLIMATION in radians, with a being, as before, the diagonal's semi-axis, f the mirror focal length, H the focus-to-diagonal axial separation, and A the diagonal's minor axis, A=2a (if we designate the diagonal-to-primary separation as S, it simplifies to δ =a 2 /HS= A 2 /4HS). For the above 300mm f /5 Newtonian, it would come to 0.0039, or0.22 degrees.
HINDLE SPHERE TEST
FIGURE 56: The Hindle sphere test setup: light source is at the far focus (FF) of the convex surface of the radius of curvature R C and eccentricity ε, and Hindle sphere center of curvature coincides with its near focus (NF).Far focus is at a distance A=R C /(1-ε) from convex surface, and the radius of curvature (R S) of the Hindle sphere is a sum of the mirror separation and near focus (NF AMATEUR TELESCOPE OPTICS Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
STAR TESTING TELESCOPE OPTICAL QUALITY As mentioned, actual instrument will most often have a mixture of different aberrations. Characteristic patterns for some other aberration forms are given in FIG. 96. Harold Suiter's "Star Testing Astronomical Telescopes" discusses in details star testing, connecting it to the underlying optical theory.An interesting new development (relatively speaking) is Roddier's test, (freeware) which TELESCOPE SYSTEMS: DESIGN SPECIFICATIONS Telescope systems: design specifications. D =diameter f =f.l./D K =conic R =surface radius S =separation M =medium A =air RI =best image curvature A4 / A6 =aspheric coefficients T =tilt (deg.) NEWTONIAN. D. SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear EFFECTS OF THE TELESCOPE CENTRAL OBSTRUCTION FIGURE 105: The effect of D/3 c. obstruction on contrast transfer with sinusoidal pattern (left) and square-wave pattern (right).Bottom plots show a direct comparison of contrast transfers for unobstructed (left) and obstructed aperture (right). Central obstruction does lower contrast for both, sinusoidal and square-wave patterns, but it degrades the low-contrast resolution limit only with the TWO-MIRROR TELESCOPES: CASSEGRAIN, GREGORIAN AND VARIANTS Classical two-mirror arrangements are Gregorian - the very first reflective telescope design, conceived by James Gregory in 1663 - and Cassegrain ( FIG. 121 ), probably introduced in 1672 by Laurent Cassegrain. In the former, concave secondary mirror is placed outside the focal point of the primary mirror, and in the latter the secondaryis
DESIGNING DOUBLET ACHROMAT Designing doublet lens objective is quite complex procedure. The reason is obvious: there is four optical surfaces, whose synergistic effect needs to correct both monochromatic and chromatic aberrations. Follows one possible solution. The goal here is a coma-free air-spaced doublet achromat (contact type), also corrected for sphericalaberration.
REFRACTING TELESCOPE OBJECTIVE: SEMI-APO AND APO … Based on the technical definition, a 100mm ƒ /12 refracting objective needs to have secondary spectrum reduced between 4 and 10 times vs. standard achromat (1 wave P-V of defocus in the C and F, 1.8 in the red r, and 4.9 waves in the violet g ), in order to reach the "true apo" level. An ƒ /6 objective, twice as much. APODIZING MASK FOR TELESCOPES FIGURE 111A: Apodizing filter modulates wave amplitude (A) in the pupil according to the Gaussian function A=exp-(r/w) 2, where exp is the natural logarithm base (Euler number, e) 2.718 under the negative exponent, in which r is the height in the pupil normalized to 1 (with 1 corresponding to the aperture radius, D/2) and w the Gaussian radius, at which transmission (t) drops to 1/e. MAKSUTOV-CASSEGRAIN TELESCOPE: OFF-AXIS ABERRATIONS 10.2.3.5. Maksutov-Cassegrain telescope off-axis aberrations. Off-axis aberrations of the meniscus, unlike those of the Schmidt corrector, are not negligible. Both coma and astigmatism of the meniscus are of the opposite sign to those of the primary mirror, and of the same sign as those at the secondary. AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clearFOUCAULT TEST
4.8.2. Foucault test. Invented by the French scientist Leon Foucault in 1858, this ingenious test uses point source of light placed at the center of curvature of a concave mirror (in practice, slightly to the side, so that the mirror focus is separated from the source, and TELESCOPE ASTIGMATISM Telescope astigmatism. Similarly to coma, astigmatism is an off-axis point wavefront aberration, caused by obliquity of the incident wavefront relative to the optical surface. Astigmatism results simply from the projectional asymmetry arising from wavefront's inclination to the optical surface. The diameter of wavefront's projection ontothe
NEWTONIAN TELESCOPE COLLIMATION in radians, with a being, as before, the diagonal's semi-axis, f the mirror focal length, H the focus-to-diagonal axial separation, and A the diagonal's minor axis, A=2a (if we designate the diagonal-to-primary separation as S, it simplifies to δ =a 2 /HS= A 2 /4HS). For the above 300mm f /5 Newtonian, it would come to 0.0039, or0.22 degrees.
HINDLE SPHERE TEST
FIGURE 56: The Hindle sphere test setup: light source is at the far focus (FF) of the convex surface of the radius of curvature R C and eccentricity ε, and Hindle sphere center of curvature coincides with its near focus (NF).Far focus is at a distance A=R C /(1-ε) from convex surface, and the radius of curvature (R S) of the Hindle sphere is a sum of the mirror separation and near focus (NF AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clearFOUCAULT TEST
4.8.2. Foucault test. Invented by the French scientist Leon Foucault in 1858, this ingenious test uses point source of light placed at the center of curvature of a concave mirror (in practice, slightly to the side, so that the mirror focus is separated from the source, and TELESCOPE ASTIGMATISM Telescope astigmatism. Similarly to coma, astigmatism is an off-axis point wavefront aberration, caused by obliquity of the incident wavefront relative to the optical surface. Astigmatism results simply from the projectional asymmetry arising from wavefront's inclination to the optical surface. The diameter of wavefront's projection ontothe
NEWTONIAN TELESCOPE COLLIMATION in radians, with a being, as before, the diagonal's semi-axis, f the mirror focal length, H the focus-to-diagonal axial separation, and A the diagonal's minor axis, A=2a (if we designate the diagonal-to-primary separation as S, it simplifies to δ =a 2 /HS= A 2 /4HS). For the above 300mm f /5 Newtonian, it would come to 0.0039, or0.22 degrees.
HINDLE SPHERE TEST
FIGURE 56: The Hindle sphere test setup: light source is at the far focus (FF) of the convex surface of the radius of curvature R C and eccentricity ε, and Hindle sphere center of curvature coincides with its near focus (NF).Far focus is at a distance A=R C /(1-ε) from convex surface, and the radius of curvature (R S) of the Hindle sphere is a sum of the mirror separation and near focus (NF AMATEUR TELESCOPE OPTICS Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
SEEING AND APERTURE
The very nature of seeing - its constant fluctuation around the average value and, in an extended time frame, fluctuation of the average itself, benefit larger aperture more when swinging above the average. For given seeing level, D/r 0 value most of the time remains within 50%, and ~25% deviations can represent appreciable portion ofthe time.
STAR TESTING TELESCOPE OPTICAL QUALITY As mentioned, actual instrument will most often have a mixture of different aberrations. Characteristic patterns for some other aberration forms are given in FIG. 96. Harold Suiter's "Star Testing Astronomical Telescopes" discusses in details star testing, connecting it to the underlying optical theory.An interesting new development (relatively speaking) is Roddier's test, (freeware) which TELESCOPE SYSTEMS: DESIGN SPECIFICATIONS Telescope systems: design specifications. D =diameter f =f.l./D K =conic R =surface radius S =separation M =medium A =air RI =best image curvature A4 / A6 =aspheric coefficients T =tilt (deg.) NEWTONIAN. D. SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear EFFECTS OF THE TELESCOPE CENTRAL OBSTRUCTION The effects of central obstruction are: (1) reduction in light transmission by a factor of (1- ο2 ), resulting from pupil obscuration, (2) reduction in the relative peak diffraction intensity - and the energy content of the central maxima - by a factor (1- ο2) 2, and. (3) longitudinal extension of DESIGNING DOUBLET ACHROMAT Designing doublet lens objective is quite complex procedure. The reason is obvious: there is four optical surfaces, whose synergistic effect needs to correct both monochromatic and chromatic aberrations. Follows one possible solution. The goal here is a coma-free air-spaced doublet achromat (contact type), also corrected for sphericalaberration.
TWO-MIRROR TELESCOPES: CASSEGRAIN, GREGORIAN AND VARIANTS Classical two-mirror arrangements are Gregorian - the very first reflective telescope design, conceived by James Gregory in 1663 - and Cassegrain ( FIG. 121 ), probably introduced in 1672 by Laurent Cassegrain. In the former, concave secondary mirror is placed outside the focal point of the primary mirror, and in the latter the secondaryis
REFRACTING TELESCOPE OBJECTIVE: SEMI-APO AND APO … Based on the technical definition, a 100mm ƒ /12 refracting objective needs to have secondary spectrum reduced between 4 and 10 times vs. standard achromat (1 wave P-V of defocus in the C and F, 1.8 in the red r, and 4.9 waves in the violet g ), in order to reach the "true apo" level. An ƒ /6 objective, twice as much. MAKSUTOV-CASSEGRAIN TELESCOPE: OFF-AXIS ABERRATIONS 10.2.3.5. Maksutov-Cassegrain telescope off-axis aberrations. Off-axis aberrations of the meniscus, unlike those of the Schmidt corrector, are not negligible. Both coma and astigmatism of the meniscus are of the opposite sign to those of the primary mirror, and of the same sign as those at the secondary. AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
SEEING AND APERTURE
The very nature of seeing - its constant fluctuation around the average value and, in an extended time frame, fluctuation of the average itself, benefit larger aperture more when swinging above the average. For given seeing level, D/r 0 value most of the time remains within 50%, and ~25% deviations can represent appreciable portion ofthe time.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
SEEING AND APERTURE
The very nature of seeing - its constant fluctuation around the average value and, in an extended time frame, fluctuation of the average itself, benefit larger aperture more when swinging above the average. For given seeing level, D/r 0 value most of the time remains within 50%, and ~25% deviations can represent appreciable portion ofthe time.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
SCHMIDT-CASSEGRAIN TELESCOPE (SCT) FIGURE 174: Schmidt-Cassegrain telescope is a Cassegrain-like two-mirror system combined with a full-aperture Schmidt corrector.Various combinations of corrector separation and mirror conics are possible, with somewhat different image field properties. Prevailing commercial arrangement is a compact design with fast spherical primary and usually also spherical secondary mirror,resulting in ~ƒ
TELESCOPE ASTIGMATISM FIGURE 43A: RIGHT: Primary astigmatism on mirror surface, as a result of the projected diameter of the incoming wavefront (W i) varying with the radial orientation.For the inclination angle shown, the width of vertical, or tangential (with the tangential plane determined by the axis and chief ray) wavefront projection onto the surface, given by cosαD, is at its minimum, gradually increasing EFFECTS OF THE TELESCOPE CENTRAL OBSTRUCTION FIGURE 105: The effect of D/3 c. obstruction on contrast transfer with sinusoidal pattern (left) and square-wave pattern (right).Bottom plots show a direct comparison of contrast transfers for unobstructed (left) and obstructed aperture (right). Central obstruction does lower contrast for both, sinusoidal and square-wave patterns, but it degrades the low-contrast resolution limit only with theDIFFRACTION
DIFFRACTION. According to the Huygens' principle, every wavefront point is a source of secondary spherical wavelets, which spread out in the direction of propagation ( FIG. 1, top/middle). This constitutes a micro-structure of energy field propagation, with the energy advancing in the direction of the wavefront, but also spreading out in other DESIGNING DOUBLET ACHROMAT Designing doublet lens objective is quite complex procedure. The reason is obvious: there is four optical surfaces, whose synergistic effect needs to correct both monochromatic and chromatic aberrations. Follows one possible solution. The goal here is a coma-free air-spaced doublet achromat (contact type), also corrected for sphericalaberration.
SEMI-APO AND APO LENS OBJECTIVE, EXAMPLES Semi-apo and apo lens objective examples. PAGE HIGHLIGHTS. • LA graphs, all-spherical • LA graphs, aspherized • Common glass apos. Within constraints given on previous page, a number of apochromatic and some viable semi-apochromatic glass combinations are possible. More than a few have been, at some point in time, used for commercial NEWTONIAN TELESCOPE COLLIMATION FIGURE 116: TOP: Visual alignment of the focuser, diagonal and primary mirror in a perfectly aligned Newtonian reflector with unoffset diagonal flat.Since the diagonal is not centered in the axial cone, so is not reflection of the primary in it. Diagonal itself, being on primary's axis, is projected to the focus centered around it, as indicated by a ray from the top diagonal point. EFFECTS OF WAVEFRONT ABERRATIONS Effects of wavefront aberrations on image quality is a fairly complex subject. Any deviation in the wavefront form away from spherical causes deterioration in the quality of point images, thus also quality of the image as a whole. The hard part is to define the specifics of this general fact. Assessing the relation between optical aberrations DALL-KIRKHAM TELESCOPE An interesting two-mirror variant is one with the secondary left spherical. It is known as Dall-Kirkham and, although with stronger coma than its classical counterparts, its mirrors are easier to make, and its miscollimation sensitivity is considerably lower than in either classical or aplanatic Cassegrain, which makes it a viable practical alternative. AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
SEEING AND APERTURE
The very nature of seeing - its constant fluctuation around the average value and, in an extended time frame, fluctuation of the average itself, benefit larger aperture more when swinging above the average. For given seeing level, D/r 0 value most of the time remains within 50%, and ~25% deviations can represent appreciable portion ofthe time.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
SEEING AND APERTURE
The very nature of seeing - its constant fluctuation around the average value and, in an extended time frame, fluctuation of the average itself, benefit larger aperture more when swinging above the average. For given seeing level, D/r 0 value most of the time remains within 50%, and ~25% deviations can represent appreciable portion ofthe time.
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant TELESCOPE EYEPIECE: COMPARATIVE RAY TRACING telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
OFF-AXIS AND TILTED ELEMENT TELESCOPES 1 8.4. Off-axis and tilted component telescopes; Herschelian reflector. Axially symmetric reflective telescopes have disadvantage of the smaller mirror being in the light path, causing additional diffraction effect degrading image quality. In order to avoid it, one or more mirrors either have to be tilted, or made as an off-axis segment of a SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
SCHMIDT-CASSEGRAIN TELESCOPE (SCT) FIGURE 174: Schmidt-Cassegrain telescope is a Cassegrain-like two-mirror system combined with a full-aperture Schmidt corrector.Various combinations of corrector separation and mirror conics are possible, with somewhat different image field properties. Prevailing commercial arrangement is a compact design with fast spherical primary and usually also spherical secondary mirror,resulting in ~ƒ
SEMI-APO AND APO LENS OBJECTIVE, EXAMPLES Semi-apo and apo lens objective examples. PAGE HIGHLIGHTS. • LA graphs, all-spherical • LA graphs, aspherized • Common glass apos. Within constraints given on previous page, a number of apochromatic and some viable semi-apochromatic glass combinations are possible. More than a few have been, at some point in time, used for commercial EFFECTS OF THE TELESCOPE CENTRAL OBSTRUCTION FIGURE 105: The effect of D/3 c. obstruction on contrast transfer with sinusoidal pattern (left) and square-wave pattern (right).Bottom plots show a direct comparison of contrast transfers for unobstructed (left) and obstructed aperture (right). Central obstruction does lower contrast for both, sinusoidal and square-wave patterns, but it degrades the low-contrast resolution limit only with the TELESCOPE ASTIGMATISM FIGURE 43A: RIGHT: Primary astigmatism on mirror surface, as a result of the projected diameter of the incoming wavefront (W i) varying with the radial orientation.For the inclination angle shown, the width of vertical, or tangential (with the tangential plane determined by the axis and chief ray) wavefront projection onto the surface, given by cosαD, is at its minimum, gradually increasing DESIGNING DOUBLET ACHROMAT Designing doublet lens objective is quite complex procedure. The reason is obvious: there is four optical surfaces, whose synergistic effect needs to correct both monochromatic and chromatic aberrations. Follows one possible solution. The goal here is a coma-free air-spaced doublet achromat (contact type), also corrected for sphericalaberration.
DIFFRACTION
DIFFRACTION. According to the Huygens' principle, every wavefront point is a source of secondary spherical wavelets, which spread out in the direction of propagation ( FIG. 1, top/middle). This constitutes a micro-structure of energy field propagation, with the energy advancing in the direction of the wavefront, but also spreading out in other EFFECTS OF WAVEFRONT ABERRATIONS Effects of wavefront aberrations on image quality is a fairly complex subject. Any deviation in the wavefront form away from spherical causes deterioration in the quality of point images, thus also quality of the image as a whole. The hard part is to define the specifics of this general fact. Assessing the relation between optical aberrations NEWTONIAN TELESCOPE COLLIMATION FIGURE 116: TOP: Visual alignment of the focuser, diagonal and primary mirror in a perfectly aligned Newtonian reflector with unoffset diagonal flat.Since the diagonal is not centered in the axial cone, so is not reflection of the primary in it. Diagonal itself, being on primary's axis, is projected to the focus centered around it, as indicated by a ray from the top diagonal point. DALL-KIRKHAM TELESCOPE An interesting two-mirror variant is one with the secondary left spherical. It is known as Dall-Kirkham and, although with stronger coma than its classical counterparts, its mirrors are easier to make, and its miscollimation sensitivity is considerably lower than in either classical or aplanatic Cassegrain, which makes it a viable practical alternative. AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
SCHMIDT-CASSEGRAIN TELESCOPE (SCT)SCHMIDT CASSEGRAIN TELESCOPE DIAGRAMSCHMIDT CASSEGRAIN DESIGNSCHMIDT CASSEGRAIN VS MAKSUTOV CASSEGRAIN16 INCH SCHMIDT CASSEGRAIN TELESCOPE FIGURE 174: Schmidt-Cassegrain telescope is a Cassegrain-like two-mirror system combined with a full-aperture Schmidt corrector.Various combinations of corrector separation and mirror conics are possible, with somewhat different image field properties. Prevailing commercial arrangement is a compact design with fast spherical primary and usually also spherical secondary mirror,resulting in ~ƒ
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant TELESCOPE EYEPIECE: COMPARATIVE RAY TRACINGDELOS EYEPIECE REVIEWTELEVUE EYEPIECE SPECSPLOSSL EYEPIECE REVIEWSUPER PLOSSL EYEPIECETELEVUE DELOS EYEPIECE REVIEWSTELEVUE DELITE EYEPIECE REVIEWS telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear TWO-MIRROR TELESCOPES: CASSEGRAIN, GREGORIAN AND VARIANTSGREGORIAN TELESCOPE DESIGNGREGORIAN TELESCOPE DESIGNJAMES GREGORY TELESCOPEJAMESGREGORY TELESCOPE
Classical two-mirror arrangements are Gregorian - the very first reflective telescope design, conceived by James Gregory in 1663 - and Cassegrain ( FIG. 121 ), probably introduced in 1672 by Laurent Cassegrain. In the former, concave secondary mirror is placed outside the focal point of the primary mirror, and in the latter the secondaryis
THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
EFFECTS OF THE TELESCOPE CENTRAL OBSTRUCTIONASTRONOMY TELESCOPE FOR SALETELESCOPE FOR SALETELESCOPE OPTICS EXPLAINEDTELESCOPE OPTICS KITUNIVERSITY OPTICS TELESCOPE The effects of central obstruction are: (1) reduction in light transmission by a factor of (1- ο2 ), resulting from pupil obscuration, (2) reduction in the relative peak diffraction intensity - and the energy content of the central maxima - by a factor (1- ο2) 2, and. (3) longitudinal extension of REFRACTING TELESCOPE OBJECTIVE: SEMI-APO AND APO …TELESCOPE OPTICS KITTELESCOPE FOR SALETELESCOPE OPTICS PDFTELESCOPE OPTICS EXPLAINEDBEST TELESCOPE FOR THE MONEY60MM APO TRIPLET Based on the technical definition, a 100mm ƒ /12 refracting objective needs to have secondary spectrum reduced between 4 and 10 times vs. standard achromat (1 wave P-V of defocus in the C and F, 1.8 in the red r, and 4.9 waves in the violet g ), in order to reach the "true apo" level. An ƒ /6 objective, twice as much. LIMITATIONS TO THE STANDARD KOLMOGOROV MODEL OF TURBULENCEKOLMOGOROV MODELKOLMOGOROV FLOWKOLMOGOROV LENGTH SCALEKOLMOGOROV SCALINGKOLMOGOROV THEORYKOLMOGOROV LENGTH SCALE OF TURBULENCE 5.1.2. Limitations to the standard Kolmogorov model of turbulence. The conventional Kolmogorov model of atmospheric turbulence is strictly valid for an inertial range of turbulence with the size much smaller than its outer scale - the large scale air movement at which the turbulence is initiated - and much larger than its inner scale, at which the turbulence is dissipated by air viscosity. AMATEUR TELESCOPE OPTICSDESIGNING DOUBLET ACHROMATSECONDARY SPECTRUM AND SPHEROCHROMATISMPOINT SPREAD FUNCTION Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
SCHMIDT-CASSEGRAIN TELESCOPE (SCT)SCHMIDT CASSEGRAIN TELESCOPE DIAGRAMSCHMIDT CASSEGRAIN DESIGNSCHMIDT CASSEGRAIN VS MAKSUTOV CASSEGRAIN16 INCH SCHMIDT CASSEGRAIN TELESCOPE FIGURE 174: Schmidt-Cassegrain telescope is a Cassegrain-like two-mirror system combined with a full-aperture Schmidt corrector.Various combinations of corrector separation and mirror conics are possible, with somewhat different image field properties. Prevailing commercial arrangement is a compact design with fast spherical primary and usually also spherical secondary mirror,resulting in ~ƒ
OPTICAL MISALIGNMENT AND FORCED SURFACE DEFORMATIONS FIGURE 90: Misaligned optical surface can be tilted, decentered, despaced, or any combination of the three in respect to its proper position.Tilt is expressed in angular form, while decenter and despace are linear quantities. Tilt and decenter result in one side of the optical surface becoming closer to the wavefront than the other one - a recipe for coma, which is by far the dominant TELESCOPE EYEPIECE: COMPARATIVE RAY TRACINGDELOS EYEPIECE REVIEWTELEVUE EYEPIECE SPECSPLOSSL EYEPIECE REVIEWSUPER PLOSSL EYEPIECETELEVUE DELOS EYEPIECE REVIEWSTELEVUE DELITE EYEPIECE REVIEWS telescope eyepiece. S: COMPARATIVE RAYTRACING. In order for any two eyepieces to be comparable with respect to their ray trace output, they have to be of the same focal length, and used at the same focal ratio. In general, the lar ger focal length at a given focal ratio, the larger geometric blur; however, since magnification drops in thesame
SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear TWO-MIRROR TELESCOPES: CASSEGRAIN, GREGORIAN AND VARIANTSGREGORIAN TELESCOPE DESIGNGREGORIAN TELESCOPE DESIGNJAMES GREGORY TELESCOPEJAMESGREGORY TELESCOPE
Classical two-mirror arrangements are Gregorian - the very first reflective telescope design, conceived by James Gregory in 1663 - and Cassegrain ( FIG. 121 ), probably introduced in 1672 by Laurent Cassegrain. In the former, concave secondary mirror is placed outside the focal point of the primary mirror, and in the latter the secondaryis
THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
EFFECTS OF THE TELESCOPE CENTRAL OBSTRUCTIONASTRONOMY TELESCOPE FOR SALETELESCOPE FOR SALETELESCOPE OPTICS EXPLAINEDTELESCOPE OPTICS KITUNIVERSITY OPTICS TELESCOPE The effects of central obstruction are: (1) reduction in light transmission by a factor of (1- ο2 ), resulting from pupil obscuration, (2) reduction in the relative peak diffraction intensity - and the energy content of the central maxima - by a factor (1- ο2) 2, and. (3) longitudinal extension of REFRACTING TELESCOPE OBJECTIVE: SEMI-APO AND APO …TELESCOPE OPTICS KITTELESCOPE FOR SALETELESCOPE OPTICS PDFTELESCOPE OPTICS EXPLAINEDBEST TELESCOPE FOR THE MONEY60MM APO TRIPLET Based on the technical definition, a 100mm ƒ /12 refracting objective needs to have secondary spectrum reduced between 4 and 10 times vs. standard achromat (1 wave P-V of defocus in the C and F, 1.8 in the red r, and 4.9 waves in the violet g ), in order to reach the "true apo" level. An ƒ /6 objective, twice as much. LIMITATIONS TO THE STANDARD KOLMOGOROV MODEL OF TURBULENCEKOLMOGOROV MODELKOLMOGOROV FLOWKOLMOGOROV LENGTH SCALEKOLMOGOROV SCALINGKOLMOGOROV THEORYKOLMOGOROV LENGTH SCALE OF TURBULENCE 5.1.2. Limitations to the standard Kolmogorov model of turbulence. The conventional Kolmogorov model of atmospheric turbulence is strictly valid for an inertial range of turbulence with the size much smaller than its outer scale - the large scale air movement at which the turbulence is initiated - and much larger than its inner scale, at which the turbulence is dissipated by air viscosity. AMATEUR TELESCOPE OPTICS Notes on AMATEUR TELESCOPE OPTICS. On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn'tnew.
DIFFRACTION
DIFFRACTION. According to the Huygens' principle, every wavefront point is a source of secondary spherical wavelets, which spread out in the direction of propagation ( FIG. 1, top/middle). This constitutes a micro-structure of energy field propagation, with the energy advancing in the direction of the wavefront, but also spreading out in other SPIDER VANES DIFFRACTION normalized central diffraction intensity caused by spider diffraction is, in effect, the ratio of the clear (annular) pupil area with and without the vanes, squared, or . with N being the vane count, τ the relative vane thickness and ο the relative size of central obstruction, both in units of the aperture diameter. The negative factor equals the relative spider area in units of the clear THE EFFECTS OF OPTICAL COATINGS AND GLASS INHOMOGENEITY ON THE EFFECT OF TRANSMISSION MATERIALS ON IMAGE QUALITY: GLASS AND COATINGS. Unless perfectly homogeneous (glass) or forming a perfectly even layer (coatings), transmission materials in an optical system inevitably change optical wavefront. The imperfections advance or delay parts of it, causing phase disarray at the focus, and transferof energy
NEWTONIAN TELESCOPE COLLIMATION FIGURE 116: TOP: Visual alignment of the focuser, diagonal and primary mirror in a perfectly aligned Newtonian reflector with unoffset diagonal flat.Since the diagonal is not centered in the axial cone, so is not reflection of the primary in it. Diagonal itself, being on primary's axis, is projected to the focus centered around it, as indicated by a ray from the top diagonal point. SEEING ERROR IN A TELESCOPE FIGURE 84: The plots are showing that the seeing FWHM is significantly smaller for short vs. long exposure.The difference is largest at . D/r 0 ~1 or less, gradually diminishing toward larger D/r 0 values.. Limit to the long exposure resolution is generally somewhat larger than λ/r 0, more in accord with 1.2λ/r 0 or 1.27λ/r 0 However, the specific value of the numerical portion varies with DESIGNING DOUBLET ACHROMAT Designing doublet lens objective is quite complex procedure. The reason is obvious: there is four optical surfaces, whose synergistic effect needs to correct both monochromatic and chromatic aberrations. Follows one possible solution. The goal here is a coma-free air-spaced doublet achromat (contact type), also corrected for sphericalaberration.
CATADIOPTRIC TELESCOPES WITH SUB-APERTURE CORRECTORS Catadioptric telescopes with Sub-aperture correctors. 10.1.1. Sub-aperture corrector aberrations. Unlike telescope objectives and most full-aperture corrector arrangements, sub-aperture correctors are usually positioned in a converging light cone. In other words, these MTF - MODULATION TRANSFER FUNCTION - TELESCOPE OPTICS Modulation transfer function (MTF) is commonly used to describe the convolution of point spread functions and the Gaussian (geometric) image of an object that is a continuous sinusoidal intensity pattern, in effect a continuum of dark and bright lines gradually changing from the maxima (in the middle of the bright line) to minima (middle of thedark line).
FOUCAULT TEST
4.8.2. Foucault test. Invented by the French scientist Leon Foucault in 1858, this ingenious test uses point source of light placed at the center of curvature of a concave mirror (in practice, slightly to the side, so that the mirror focus is separated from the source, and _ "МОЖДА СУ ЦРНЕ ТАЧКЕ БИЛЕ ПТИЦЕ У ЛЕТУ..." (MAYBE THE BLACK DOTS WERE BIRDS IN FLIGHT)_ _ NOTES ON_ AMATEUR TELESCOPE OPTICS On an early autumn day of 1608, Hans Lipperhey, a spectacle maker from Middelburg, in the Netherlands' coastal province of Zeeland, applied before the States General of The Hague for a patent on an "instrument for seeing far". By that time, use of small rounded glass disks to aid the natural eyesight wasn't new. Those bulging out on both sides, resembling lentil - or "_lens_" in Latin - have been used to correct for farsightedness since the mid 13th century. The idea of a device for magnifying distant objects may have been already grasped for some time as well. But _this_ was the beginning of something else. In the summer of 1609, Galileo, Harriot, and others, turned the new Dutch invention - the "spyglass" - toward the night sky. The telescope wasborn.
This tale grew old, but our fascination with telescopes has not. Following text is an attempt to give more of an insight into their inner workings. More specifically, how do they form images and what factors determine their quality. Somewhat unusual, the main aspect is that of the optical wavefront, as opposed to the geometric (ray) "interface". That deliberate choice, while perhaps somewhat less convenient, allows for more accurate qualitative assessment, and should throw more light at the underlying physical fundamentals. Main reference sources are as follows: (1) _Astronomical Optics_, Daniel J. Schroeder, (2) _ Aberration Theory Made Simple_, Virendra N. Mahajan, (3) _Optical Imaging and Aberrations_ I and II, Virendra N. Mahajan, (4) _Optics_, Eugene Hecht, and (5) _Telescope Optics_, Harrie Rutten and Martin van Venrooij. Most of raytracing plots and routine checkups are by ATMOS , Massimo Riccardi, and OSLO , Sinclair Optics. Most of diffraction patterns were generated by Aberrator, Cor Berrevoets.
For additional reading, see extensive coverage of telescope optics and related subjects at Bruce MacEvoy's Astronomical optics (descriptive), and SoloHermelin's Optics
(mathematical). For related graphic aspects, Wyant Collegewebsite.
TABLE OF CONTENTS:
1. IMAGE FORMATION IN A TELESCOPE Rays and waves DiffractionPSF
1.2. REFLECTION AND REFRACTION 1.3. OPTICAL SYSTEM OF A TELESCOPE 1.3.1 GAUSSIAN APPROXIMATION 2. TELESCOPE FUNCTIONS2.1. LIGHT GRASP
2.2. RESOLUTION
2.3. MAGNIFICATION
3. TELESCOPE ABERRATIONS: TYPES, CAUSES 3.1. WAVEFRONT ABERRATIONS 3.2. RAY (GEOMETRIC) ABERRATIONS 3.3. CONICS AND ABERRATIONS 2 3.4. TERMS AND CONVENTIONS 3.5. ABERRATION FUNCTION SeidelZernike 2
3
4. INTRINSIC TELESCOPE ABERRATIONS 4.1. SPHERICAL Primary2
Higher-order
4.2. COMA 4.3. ASTIGMATISM4.4. DEFOCUS
4.5. DISTORTION 4.6. FIELD CURVATURE 4.7. CHROMATISM axiallateral
effect
4.8. FABRICATION ERRORS 4.8.1.Optical tests
Double pass test Interferometry Foucault Ronchi WaineoHindle Dall/Ross
Offner
4.9. TRANSMISSION MATERIALS EFFECTSglass coatings
5. INDUCED ABERRATIONS 5.1. AIR-MEDIUM ERRORS Seeing error Model limitationsSeeing and aperture
The seeing Strehl, resolution, OTF 5.2. Low-level turbulence, tube currents, atmospheric refraction/dispersion 5.3. ALIGNMENT ERRORS 5.4. FORCE-INDUCED SURFACE ERRORS 6. EFFECTS OF WAVEFRONT ABERRATIONS 6.1. ABERRATIONS AND OPTICAL QUALITY: CRITERIA 6.2. GENERAL EFFECTS 6.3. OBJECT TYPE RELATED 2 6.4. DIFFRACTION PATTERNStar test
6.5. STREHL RATIO 6.6. MTF 23
7. OBSTRUCTION EFFECTS 23
4 5
8. REFLECTING OBJECTIVES 8.1. NEWTONIAN off-axiscollimation
diagonal flat
8.2. ALL-REFLECTING TWO-MIRROR 23
4 5
6
8.3. THREE-MIRROR
Cassegrain-Gregorian Paul-BakerFAA
8.4. OFF-AXIS AND TILTED ELEMENTS Herschelian 2-mirror TCT2 off-axis
Newtonian
9. REFRACTING OBJECTIVE AchromatApo 2
•
Designing
10. CATADIOPTRIC TELESCOPES 10.1. SUB-APERTURE LENS CAT S2 3
4 •
10.2. FULL-APERTURE LENS CATS 10.2.1. DIALYTES HamiltonSchupmann
Busack/Honders
10.2.2. SCHMIDT CORRECTORSchmidt camera 2
Wright, Baker, HyperstarSN
SCT 2 3 SC
camera
10.2.3. MENISCUS CORRECTOR Bowers/Maksutov camera 2MN MCT
2 3
10.2.4. HOUGHTON CORRECTORHoughton camera 2
HN HCT
2 3
4 5
11. MISCELLANEOUS OPTICS 12. TELESCOPE EYEPIECE 23 4
13. THE TELESCOPIC EYEAberrations 2
3
4
5 6
Response
2
14. TELESCOPES • Past • ATM • Observatory• Commercial
•
APPENDIX: Telescope specifications 23 4
• UPDATED February/March 2021www site
Web-published on July 14. 2006. by Vladimir SacekDetails
Copyright © 2024 ArchiveBay.com. All rights reserved. Terms of Use | Privacy Policy | DMCA | 2021 | Feedback | Advertising | RSS 2.0