WO2015111036A1 - Système optique anamorphique permettant une résolution de sources ponctuelles hors axe - Google Patents

Système optique anamorphique permettant une résolution de sources ponctuelles hors axe Download PDF

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Publication number
WO2015111036A1
WO2015111036A1 PCT/IL2014/051088 IL2014051088W WO2015111036A1 WO 2015111036 A1 WO2015111036 A1 WO 2015111036A1 IL 2014051088 W IL2014051088 W IL 2014051088W WO 2015111036 A1 WO2015111036 A1 WO 2015111036A1
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WO
WIPO (PCT)
Prior art keywords
light
optical
optical system
plane
anamorphic
Prior art date
Application number
PCT/IL2014/051088
Other languages
English (en)
Inventor
Shahar NIR
Eyal ARAD
Paula ROIT
Original Assignee
Rafael Advanced Defense Systems Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to IL23064014A priority Critical patent/IL230640B/en
Application filed by Rafael Advanced Defense Systems Ltd. filed Critical Rafael Advanced Defense Systems Ltd.
Publication of WO2015111036A1 publication Critical patent/WO2015111036A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/08—Anamorphotic objectives

Definitions

  • the present invention relates to anamorphic optics and, more particularly, to an anamorphic optical system with better off-axis resolution of point sources than those known heretofore.
  • Figures 1A and IB illustrate anamorphic squeezing of a scene.
  • Figure 1A depicts a typical scene as it would be imaged by a camera whose optics are not anamorphic and whose angular field of view is 3.86 times as wide as it is high.
  • Figure IB depicts what image of the scene of Figure 1 A looks like after being squeezed horizontally and/or stretched vertically to be only 1.25 times as wide as it is high.
  • a camera with anamorphic infrared optics could image just the terrain of interest using a single conventional detector array: the anamorphic optics would squeeze the incident light of a field of view such as the field of view depicted in Figure 1A so that substantially all of the light is focused on substantially all of the detector array.
  • Figure 2 illustrates the coordinate system used herein.
  • Figure 2 shows the entrance plane and the exit plane of an anamorphic optical system that squeezes the incident angles of incoming light horizontally and stretches the angles of incoming light vertically.
  • the horizontal spread of the incoming angles at the entrance plane is 1 ⁇ 4>,:.
  • the vertical spread of the incoming angles at the entrance plane is h,.
  • the horizontal spread of the outgoing angles at the exit plane is w 0 .
  • the vertical spread of the outgoing angles at the exit plane is h 0 .
  • the aspect ratio of the entrance plane is cti-Wi/hi.
  • the rectilinear coordinate system of the anamorphic optical system is defined so that the exit plane is at z-0 and the z ⁇ axis points from the entrance plane to the exit plane, the xz plane is horizontal and the >>z plane is vertical.
  • anamorphic optics are designed relative to the desired, performance (at the exit plane) along the x and y axes. See for example US Patent No. 8,049,967 to Hirose that includes several instructive illustrations of on-axis spot diagrams. This results in the smearing of images of off-axis objects. This smearing is acceptable for imaging extended objects but is not acceptable in surveillance applications in which the targets are point sources of light.
  • a “point source” is understood herein as a source of light that is sufficiently compact to be treated for optical modeling purposes as a mathematical point.
  • An "infinitely distant” point source is understood herein as a point source that is sufficiently far from the system of the present invention that all light rays from the point source are effectively parallel.
  • the angular coordinate system used to describe the orientation of the incoming rays relative to the optical axis of the system at the entrance plane uses the "azimuth” and the "elevation” of a spherical coordinate system.
  • the azimuth, in the interval [-180°,180°] is measured relative to the xz plane, as shown in Figure 2.
  • the elevation, in the interval [0°,90°] is measured relative to the optical (z) axis, as shown in Figure 3, in which the direction of propagation of the light is from left to right.
  • the anamorphic optical subsystem includes an entrance plane, an exit plane and one or more optical elements, in the optical path from the entrance plane to the exit plane, that effect(s) an aspect ratio distortion, by a factor r> ⁇ , on light that has a wavelength in a predetermined interval and that enters the subsystem via the entrance plane from an infinitely distant point source at any azimuth and at any elevation up to at least about five degrees from the optical axis of the subsystem.
  • n ⁇ 0.737 Preferably, n ⁇ 0.515. More preferably, n ⁇ 0.322. Most preferably, n ⁇ 0.152.
  • the optical element(s) may be refractive and/or reflective optical elements.
  • the optical elements are refractive optical elements.
  • the predetermined wavelength interval is in the mid-infrared (3 microns to 8 microns), most preferably between about 3.6 microns and about 4.9 microns. In other preferred embodiments, the predetermined wavelength interval is an interval in the long wavelength infrared (8 microns to 15 microns), most preferably between about 8 microns and about 13 microns.
  • the system also includes a detector of the light and a rotationally symmetric optical subsystem that receives the light from the exit plane and. focuses the light on the detector.
  • the energy of the light within, the Airy disk of the light as focused on the detector also is at least about fir) of a diffraction limit of that energy.
  • Another basic embodiment of the present invention is an optical system that includes an entrance plane, a detector, and one or more optical elements in the optical path from the entrance plane to the detector.
  • the optical element(s) focus(es), onto the detector, light, from an infinitely distance point source, that enters the system via the entrance plane at any azimuth and at any elevation up to at least about five degrees and that has a wavelength in a predetermined wavelength interval.
  • the optical element(s) also effect(s) an aspect ratio distortion by a factor of r>l, on the light.
  • the energy of the light within the Airy disk of the light as focused on the detector is at least about fir) of the diffraction limit value of that energy, where fix) is a monotonic function of x.
  • FIGs. 1 A and IB illustrate anamorphic squeezing of a scene
  • FIG. 2 illustrates the coordinate system used herein and also the definition of "azimuth"
  • FIG. 3 illustrates the definition of "elevation”
  • FIG. 5 shows plots of the fraction of enclosed energy within circles centered on the centroid of the light at the exit plane of the optics of FIGs 4A and 4B, as a function of the radii of the circles, for several entrance angles;
  • FIG. 8 shows plots of the fraction of enclosed energy within circles centered on the centroid of the light at the exit plane of the optics of FIGs 7A and 7B, as a function of the radii of the circles, for several entrance angles;
  • FIG. 10 shows plots of the fraction of enclosed energy within circles centered on the centroid of the light at the exit plane of the optics of FIGs 9A and 9B, as a function of the radii of the circles, for several entrance angles;
  • FIG. 11 is a high-level block diagram of a complete system of the present invention.
  • Figures 4A and 4B are horizontal and vertical cross sections of exemplary / -2 anamorphic optics 10 of the present invention, for mid-infrared wavelengths between 3.6 microns and 4.9 microns.
  • Lenses 16 and 18 are made of germanium. The spacing apart of entrance plane 12, lenses 16 and 18 and exit plane 14 are as shown in Figure 4A.
  • Surface 22 of lens 16 is a spherical surface of radius 147.7466 mm, concave towards exit plane 14.
  • Surface 26 of lens 18 is a spherical surface of radius 35.3941 1 mm, convex towards exit plane 14.
  • Lenses 16 and 18 are rendered anamorphic by their surfaces 20 and 24, which are defined by mixed toroidal-Zernike coefficients. 6 2014/051088
  • Toroidal surfaces are formed by defining a curve in eyz plane and then translating the curve parallel to the x-axis.
  • the curve in the yz plane is defined by
  • Zernike polynomials Z are as defined by Noll
  • p is the normalized radial coordinate (normalized to equal 1 at the circular edge of the lens surface)
  • ⁇ is the angular coordinate.
  • the only non-zero Zernike coefficients are A ⁇ , A4, As, A ⁇ ⁇ t An, A i4, A22, A24, A.26 nd ⁇ g-
  • the corresponding polynomials are:
  • the diameter of the aperture at entrance plane 12 is 40.58 mm.
  • Lens 16 has a diameter of 38.52 mm at surface 20 and a diameter of 36 mm at surface 22.
  • Lens 18 has a diameter of 17.24 mm at surface 24 and a diameter of 1 .06 mm at surface 26.
  • the diameter of the aperture at exit plane 14 is 7.7 mm.
  • the figure of merit of the anamorphic optics of the present invention is, for rays of light that enter the entrance plane from an infinitely distant point source, the fraction of the energy of the light within the Airy disk of the light at the exit plane, relative to the value of that energy in the diffraction limit.
  • Figure 5 shows, for anamorphic optics 10, plots of the fraction of enclosed energy within circles centered on the centroid of the light at exit plane 14, as a function of the radii of the circles: one curve for the diffraction limit and four curves for the actual performance of anamorphic optics 10 for the following (azimuth, elevation) pairs for the incident directions:
  • Figure 6 shows similar curves for representative anamorphic optics of the prior art.
  • the incident directions illustrated are:
  • the two "on-axis" ((0°, 0°) and (0°, 6°)) curves are close to the diffraction limit curve, but the off-axis (20.5°, 6.4°) curve is significantly below the other three curves.
  • the off-axis enclosed energy is about half of the diffraction limit enclosed energy.
  • the first appended claim defines the present invention in terms of the figure of merit, for light from an infinitely distant point source entering the entrance plane at any azimuth (not just on-axis) and at elevations up to about 5°, being as follows.
  • the ratio of the fraction of energy of the light within the Airy disk at the exit plane to what that fraction would, be in the diffraction limit is a function/ of the aspect ration distortion factor r that obeys the following constraints:
  • Lenses 36, 38, 40 and 42 are made of germanium.
  • the spacing apart of lenses 36, 38, 40 and 42 and exit plane 34 are as shown in Figure 7 A.
  • the entrance plane (not shown) is tangent to surface 44 of lens 36 and perpendicular to the optical axis.
  • Surface 46 of lens 36 is a spherical surface of radius 487.0118 mm, concave towards exit plane 34.
  • Surface SO of lens 38 is a spherical surface of radius 44.8087 mm, concave towards exit plane 34.
  • Lenses 36 and 42 are rendered anamorphic by their surfaces 44 and 56, which are defined by mixed toroidal-Zemike coefficients, just as surfaces 20 and 24 of lenses 16 and 18 are defined.
  • the coefficients that define surfaces 44 and 56 are as in the following table.
  • Lens 36 has a diameter of 69.89 mm at surface 44 and a diameter of 68.39 mm at surface 46.
  • Lens 38 has a diameter of 36.63 mm at surface 48 and a diameter of 32. mm at surface 50.
  • Lens 40 has a diameter of 28.61 mm at surface 52 and a diameter of 27.93 mm at surface 54.
  • Lens 42 has a diameter of 16.54 mm at surface 56 and a diameter of 16.26 mm at surface 58.
  • Figure 8 shows, for anamorphic optics 30, plots of the fraction of enclosed energy within circles centered on the centroid of the light at exit plane 34, as a function of the radii of the circles: one curve for the diffraction limit ant four curves for the actual performance of anamorphic optics 30 for the following azimuth- elevation pairs:
  • Lenses 66, 68, 70 and 72 are made of germanium.
  • the spacing apart of entrance plane 62, lenses 66, 68, 70 and lens 72 and exit plane 74 are as shown in Figure A.
  • Surface 76 of lens 66 is a spherical surface of radius 438.5167 mm, concave towards exit plane 34.
  • Surface 80 of lens 68 is a spherical surface of radius 52.28051 mm, concave towards exit plane 64.
  • Surface 84 of lens 70 is a spherical surface of radius 124.5697 mm, concave towards exit plane 74.
  • Surface 88 of lens 72 is a spherical surface of radius 36.72785, convex towards exit plane 74.
  • Lenses 66 and 72 are rendered anamorphic by their surfaces 74 and 86, which are defined by mixed toroidal-Zernike coefficients, just as surfaces 20 and 24 of lenses 16 and 18 are defined.
  • the coefficients that define surfaces 44 and 56 are as in the following table.
  • Lens 66 has a diameter of 65.28 mm at surface 74 and a diameter of 63.34 mm at surface 76.
  • Lens 68 has a diameter of 41.31 mm at surface 78 and a diameter of 32.76 mm at surface 80.
  • Lens 70 has a diameter of 27.60 mm at surface 82 and a diameter of 23.56 mm at surface 84.
  • Lens 72 has a diameter of 8.96 mm at surface 86 and a diameter of 9.49 mm at surface 88.
  • Figure 10 shows, for anamorphic optics 60, plots of the fraction of enclosed energy within circles centered on the centroid of the light at exit plane 64, as a function of the radii of the circles: one curve for the diffraction limit ant four curves for the actual performance of anamorphic optics 60 for the following azimuth- elevation pairs:
  • FIG 11 is a high-level block diagram, of a complete system 100 of the present invention.
  • System 100 includes anamorphic optics 110 (of which anamorphic optics 10 is one embodiment and anamorphic optics 30 is another embodiment), non- anamorphic optics 120 and a detector array 130 such as a CCD detector array.
  • the entrance plane of anamorphic optics 110 is designated in Figure 7 by the reference numeral 112.
  • the exit plane of anamorphic optics 110 is designated in Figure 7 by the reference numeral 114.
  • Anamorphic optics 110 is afocal, and the function of non- anamorphic optics 120 is to focus the light exiting exit plane 114 onto detector array 130, so the entrance plane 122 of non-anamorphic optics 120 coincides with exit plane 114 of anamorphic optics 110.
  • Detector array 130 is placed at the exit plane of non-anamorphic optics 120.
  • the figure of merit of system 100 is similar to the figure of merit of anamorphic optics 110: for rays of light that enter entrance plane 112 from an infinitely distant point source, the fraction of the energy of the light within the Airy disk of the light at detector 130, relative to the value of that energy in the diffraction limit.
  • the ratio of the fraction of energy of the light within the Airy disk at detector array 130 to what that fraction would be in the diffraction limit is f(r), where r is the aspect ratio distortion factor of anamorphic optics 110.

Abstract

La présente invention concerne un système optique comprenant un sous-système optique anamorphique qui comprend un plan d'entrée, un plan de sortie, et au moins un élément optique, dans un trajet optique allant dudit plan d'entrée au plan de sortie, qui permet une distorsion de rapport de forme de facteur r>1, sur la lumière présentant une longueur d'onde comprise dans un intervalle de longueur d'onde prédéfini et qui pénètre dans ledit sous-système anamorphique par ledit plan d'entrée, à partir d'une source ponctuelle située à une distance infinie, à tout azimut et à une élévation quelconque supérieure à au moins environ cinq degrés par rapport à un axe optique dudit sous-système optique anamorphique, de sorte que l'énergie de ladite lumière à l'intérieur d'une tache d'Airy de ladite lumière, lorsque ladite lumière sort dudit sous-système optique anamorphique par ledit plan de sortie, est au moins environ égale à f(r) d'une valeur limite de diffraction de ladite énergie, f(x) représentant une fonction monotone de x de sorte que f(1)=1, f(1)≥- 0,737, f(2)≥0,6 et f(∞)=0.
PCT/IL2014/051088 2014-01-23 2014-12-11 Système optique anamorphique permettant une résolution de sources ponctuelles hors axe WO2015111036A1 (fr)

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Application Number Priority Date Filing Date Title
IL23064014A IL230640B (en) 2014-01-23 2014-01-23 Anamorphic optics that resolve off-axis point sources

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IL230640 2014-01-23
IL23064014A IL230640B (en) 2014-01-23 2014-01-23 Anamorphic optics that resolve off-axis point sources

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5013133A (en) * 1988-10-31 1991-05-07 The University Of Rochester Diffractive optical imaging lens systems
US6098887A (en) * 1998-09-11 2000-08-08 Robotic Vision Systems, Inc. Optical focusing device and method
US6157756A (en) * 1998-08-21 2000-12-05 Ishiwata; Samford P. Laser beam expander and beam profile converter
US20030063355A1 (en) * 1999-09-01 2003-04-03 Seizo Suzuki Optical scanning device, line-image forming optical system therein,imaging adjustment method in the device and image forming apparatus
US6661582B1 (en) * 2002-06-11 2003-12-09 Nortel Networks Limited Optical transmitter and anamorphic lens therefor
US20090303608A1 (en) * 2006-02-14 2009-12-10 Jos. Schneider Optische Werke Gmbh Optical system for digital cinema projection
US20110285995A1 (en) * 2008-11-04 2011-11-24 William Marsh Rice University Image mapping spectrometers
WO2012123592A1 (fr) * 2011-03-17 2012-09-20 Valles Navarro Alfredo Lentille anamorphique

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5013133A (en) * 1988-10-31 1991-05-07 The University Of Rochester Diffractive optical imaging lens systems
US6157756A (en) * 1998-08-21 2000-12-05 Ishiwata; Samford P. Laser beam expander and beam profile converter
US6098887A (en) * 1998-09-11 2000-08-08 Robotic Vision Systems, Inc. Optical focusing device and method
US20030063355A1 (en) * 1999-09-01 2003-04-03 Seizo Suzuki Optical scanning device, line-image forming optical system therein,imaging adjustment method in the device and image forming apparatus
US6661582B1 (en) * 2002-06-11 2003-12-09 Nortel Networks Limited Optical transmitter and anamorphic lens therefor
US20090303608A1 (en) * 2006-02-14 2009-12-10 Jos. Schneider Optische Werke Gmbh Optical system for digital cinema projection
US20110285995A1 (en) * 2008-11-04 2011-11-24 William Marsh Rice University Image mapping spectrometers
WO2012123592A1 (fr) * 2011-03-17 2012-09-20 Valles Navarro Alfredo Lentille anamorphique

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IL230640B (en) 2019-10-31

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