WO2007015236A1 - Système optique à double champ visuel - Google Patents

Système optique à double champ visuel Download PDF

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Publication number
WO2007015236A1
WO2007015236A1 PCT/IL2006/000885 IL2006000885W WO2007015236A1 WO 2007015236 A1 WO2007015236 A1 WO 2007015236A1 IL 2006000885 W IL2006000885 W IL 2006000885W WO 2007015236 A1 WO2007015236 A1 WO 2007015236A1
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WO
WIPO (PCT)
Prior art keywords
light
subpixels
detector
sensitive
spectral range
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/IL2006/000885
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English (en)
Inventor
Zvi Nizani
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rafael Advanced Defense Systems Ltd
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
Application filed by Rafael Advanced Defense Systems Ltd filed Critical Rafael Advanced Defense Systems Ltd
Publication of WO2007015236A1 publication Critical patent/WO2007015236A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • G02B13/14—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation
    • G02B13/146—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation with corrections for use in multiple wavelength bands, such as infrared and visible light, e.g. FLIR systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
    • H04N25/61—Noise processing, e.g. detecting, correcting, reducing or removing noise the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4"
    • H04N25/611—Correction of chromatic aberration
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/08—Catadioptric systems
    • G02B17/0896—Catadioptric systems with variable magnification or multiple imaging planes, including multispectral systems

Definitions

  • the invention is related to the field of optical systems. Specifically the invention is an optical system that provides a dual field of view using a single detector without the use of moving parts.
  • a familiar requirement of many optical systems is that they be able to provide two images of a scene; the first having a wide field of view at relatively low magnification and the second having a narrow field of view at higher magnification.
  • EP 0128 815 and GB 2 212 936 are two published patent applications, which describe optical systems similar to that of a Cassegrainian telescope in which the secondary mirror is coated with a dichroic layer that reflects one range of wavelengths and transmits a second range of wavelengths, thereby allowing images having two different fields of view to be focused on a single detector.
  • US 5,751,473 also describes an optical system in which images of a scene having two different fields of view are simultaneously focused on a single detector.
  • the optical system described in this publication is more complex than those of the previously described publications.
  • a cold finger which is coated in different areas with different coatings, acts as a filter, which causes spatial separation of the two images, each in its own wavelength band, on the detector surface.
  • the detector comprises two detecting layers, the first of which absorbs and detects 3-5 micron radiation and the second layer 8-12 micron radiation.
  • the electronic read-out system connected to the detector array is capable of discriminating between the images by alternately reading the signals from each of the layers of the detector, on which the energy from a particular one of the two wavelength bands falls.
  • the invention is an optical system, which simultaneously captures two images of a scene, each image having a different field of view.
  • the system of the invention has no moving parts and comprises:
  • a dichroic filter that divides the light entering the system into a first spectral range and a second spectral range.
  • a single detector having a surface comprising a matrix of pixels, each of the pixels comprising at least two subpixels. The first of the subpixels is sensitive to light in the first spectral range and the second of the subpixels is sensitive to light in the second spectral range.
  • Additional optical elements which focus the light that enters the system on the planar surface of the detector.
  • the first of the two images is captured on the subpixels that are sensitive to light in the first spectral range and the second of the two images is simultaneously captured on the subpixels that are sensitive to light in the second spectral range.
  • the light entering the system is in the visible wavelength band
  • the dichroic filter is a coating on one of the optical elements
  • the dichroic filter coating transmits blue light and reflects red light
  • the detector is a CCD comprising at least subpixels sensitive to blue light and subpixels sensitive to red light.
  • the additional optical elements comprise two groups positioned one after the other along on a common optical axis with the detector: a front group comprising a reflective afocal telescope, and a common positive lens assembly focused to infinity located between the front afocal telescope and the detector.
  • the area of the front group surrounding the optical axis has zero optical power for transmitted light and all lenses of the positive lens assembly are corrected for color aberration over the first and second spectral ranges.
  • the afocal telescope comprises: a front lens comprising a dichroic filter coating created on the central portion of the lens and an annular area surrounding the coating that is transparent to the incoming light and a primary mirror comprising an annular reflecting layer surrounding a central area that is transparent to the incoming light.
  • - Fig. 1 shows a small area comprising four pixels of a RGB CCD detector
  • - Fig. 2 is a graphical representation showing the relative response to visible light as a function of wavelength for the detector shown in Fig. 1; - Fig. 3 schematically shows an optical system according to the present invention; and - Fig. 4 shows the transmission/reflection curve of a dichroic coating suitable for use in the present invention.
  • the invention is an optical system for simultaneously capturing on a single detector two images of a scene, each image having a different field of view.
  • the system of the invention has no moving parts.
  • a dichroic filter which is coated on lens surface, is used to divide the light that enters the system into two spectral ranges and a single tricolor (RGB) CCD detector is used to capture the images.
  • RGB tricolor
  • a standard RGB CCD detector based on a Bayer Filter comprising alternate rows of red and green filters and blue and green filters is used in the device of the invention.
  • each pixel is divided into four separate areas or "subpixels" one of which is sensitive to red, one sensitive to blue, and two sensitive to green.
  • Fig. 1 shows a small area comprising four pixels of such a detector.
  • Fig. 2 is a graphical representation showing the relative response to visible light as a function of wavelength for the detector shown in Fig. 1.
  • Fig. 3 is schematically shown an optical system 10 according to the present invention.
  • the optical system shown in Fig.3 is presented in order to illustrate the principles of the invention and is not meant to limit the invention in any way.
  • Optical system 10 is a dual FOV camera having a relationship of 1:3 between the two fields of view.
  • the optical system 10 has no moving parts.
  • the scene being viewed is to the left and light arriving from the scene passes through front lens 12, primary mirror 18, and lens set 24 which act together to focus it on the face of RGB CCD detector 28. All of the elements of the system are arranged symmetrically on the optical axis 30.
  • Front lens 12 is made of a material that is transparent to visible light, i.e. optical quality glass.
  • On the central area of the back side of front lens 12 a circular dichroic filter coating 14 is created by vacuum deposition or any other technique known in the art.
  • An annular transparent region 16 surrounds the dichroic filter coating 14 on the center of lens 12.
  • Primary mirror 18 comprises a curved substrate which supports on its front surface a totally reflecting annular reflective area 20 surrounding a central circular transparent area 22.
  • the substrate can be for example made from optical glass and the reflective area made by vacuum deposition of an aluminum layer.
  • the substrate could be made of metal that is highly polished to create reflective area 20 and a large hole bored in the center to form transparent area 22.
  • the radius of curvature of primary mirror 18 is such that any ray of light that passes through the annular transparent area 16 on the front lens 12 and impinges on annular reflective area 20 will be reflected back towards the front lens and will impinge on the circular dichroic filter coating 14.
  • the radius of curvature of the front lens 12 is such that any ray of light reflected from circular dichroic filter coating 14 will pass through the transparent area 22 of the primary mirror.
  • Fig. 4 shows the transmission/reflection curve of a dichroic coating created specifically for use in the present invention.
  • the vertical axis represents the transmission/reflection as a fraction of the maximum value and the horizontal axis shows the wavelength in nanometers.
  • the transmission of the coating is shown by the solid squares and the reflection by the solid circles.
  • numeral 32 identifies a typical ray of visible light from the distant scene that impinges on the center of the front lens 12, i.e. is incident on the dichroic filter coating 14.
  • dichroic coating 14 the red components of the light are reflected backwards and are blocked from passing through the remainder of optical system 10 and reaching the detector 28.
  • the blue component of ray 32 passes through dichroic layer 14, transparent area 22 in the primary mirror 18, and lens group 24 and is focused onto the surface of CCD detector 28.
  • Numeral 34 identifies a typical ray of visible light from a distant scene that passes through the annular transparent region 16 of the front lens 12. Ray 34 will be reflected by the annular reflective coating 20 on primary mirror 18 onto the dichroic filter coating 14. When the reflected ray encounters dichroic layer 14, the blue component of ray 34 passes through front lens 12 Oand exits the optical arrangement 10. The red component of ray 34 is reflected from dichroic layer 14 and passes through transparent area 22 in the primary mirror 18 and lens group 24 and is focused onto the surface of CCD detector 28. Both the blue beam 32 and the red beam 33 travel through refractive lens set 24. The lenses of assembly 10 are corrected for color aberration in such a way as to enable the light from both beams to be focused on the same plane.
  • a filter can be provided at any convenient location in the optical path before the detector.
  • the dichroic filter can be designed in many different ways, for example to transmit red and reflect blue or to transmit/reflect green and reflect/transmit either red or blue.
  • filters may be applied on the subpixels in order to match dichroic filters and desired spectral ranges.
  • FOV view FOV of the camera
  • FOV d/f
  • d the diameter of the detector
  • f the focal length of the system.
  • FOV h/f x w/f, wherein h and w are the height and width respectively of the detector.
  • ray 32 represents the short focal length path creating the wide field of view (WFOV) image, which will be recorded on the blue subpixels of the CCD and ray 34 represents the long focal length path and narrow field of view (NFOV) image, which will be recorded on the red subpixels of the CCD.
  • WFOV wide field of view
  • NFOV narrow field of view
  • the detector is a standard ⁇ 4" CCD and the entire camera can be enclosed within a cylindrical case having a diameter of 20mm and a length of 45mm.
  • the output of the camera then is two simultaneous images; the first a blue image having a WFOV of 7x9 degrees, and the second a red image having a NFOV of 2.3x3 degrees.
  • the lens set 24 can easily be replaced with another set of lenses that will give other fields of view having the same 3:1 ratio between them, e.g. WFOV of 9x18 degrees and NFOV of 3x6 degrees.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Color Television Image Signal Generators (AREA)

Abstract

La présente invention concerne un système optique, qui capture simultanément deux images d’une scène. Le système ne comporte aucune pièce mobile et chaque image possède un champ visuel différent. Le système comprend un filtre dichroïque, un seul détecteur et d’autres éléments optiques. Le filtre dichroïque divise la lumière entrante du système en un premier domaine spectral et un second domaine spectral. Les autres éléments optiques focalisent la lumière entrante du système sur une surface planaire du détecteur, ladite surface comprenant une matrice de pixels, chaque matrice étant formée d’au moins deux sous-pixels. Un des sous-pixels est sensible à la lumière dans le premier domaine spectral et l’autre à celle dans le second domaine. La première image est capturée dans le jeu de sous-pixels sensibles à la lumière dans le premier domaine spectral et la seconde image est simultanément capturée dans l’autre jeu de sous-pixels.
PCT/IL2006/000885 2005-08-04 2006-07-31 Système optique à double champ visuel Ceased WO2007015236A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IL170125 2005-08-04
IL17012505 2005-08-04

Publications (1)

Publication Number Publication Date
WO2007015236A1 true WO2007015236A1 (fr) 2007-02-08

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IL2006/000885 Ceased WO2007015236A1 (fr) 2005-08-04 2006-07-31 Système optique à double champ visuel

Country Status (1)

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WO (1) WO2007015236A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9217671B2 (en) 2009-09-01 2015-12-22 Koninklijke Philips N.V. High spectral resolution color sensor using non-dispersive elements
US20180100996A1 (en) * 2016-10-10 2018-04-12 Northrop Grumman Systems Corporation Compact, simultaneous dual field of view through a common aperture
US11221468B2 (en) * 2013-12-20 2022-01-11 Thales Optical imaging module having a hyper-hemispherical field and controlled distortion and compatible with an outside environment
CN114895447A (zh) * 2022-04-29 2022-08-12 中国科学院长春光学精密机械与物理研究所 一种共口径多视场红外光学系统
US20240369814A1 (en) * 2018-06-27 2024-11-07 The Charles Stark Draper Laboratory, Inc. Multiple Effective Focal Length (EFL) Optical System

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4453800A (en) * 1981-08-17 1984-06-12 Rockwell International Corporation Selectable field-of-view infrared lens
EP0128815A2 (fr) * 1983-06-08 1984-12-19 R.E.O.S.C. (Recherches Et Etudes D'optique Et De Sciences Connexes) Dispositif d'observation optique à deux champs
US4956555A (en) * 1989-06-30 1990-09-11 Rockwell International Corporation Multicolor focal plane arrays
EP0490497A2 (fr) * 1990-12-13 1992-06-17 Hughes Aircraft Company Dispositif pour l'observation simultané de deux champs de vision
US20030218686A1 (en) * 2002-05-21 2003-11-27 Lundgren Mark A. Multiple field of view telescope

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4453800A (en) * 1981-08-17 1984-06-12 Rockwell International Corporation Selectable field-of-view infrared lens
EP0128815A2 (fr) * 1983-06-08 1984-12-19 R.E.O.S.C. (Recherches Et Etudes D'optique Et De Sciences Connexes) Dispositif d'observation optique à deux champs
US4956555A (en) * 1989-06-30 1990-09-11 Rockwell International Corporation Multicolor focal plane arrays
EP0490497A2 (fr) * 1990-12-13 1992-06-17 Hughes Aircraft Company Dispositif pour l'observation simultané de deux champs de vision
US20030218686A1 (en) * 2002-05-21 2003-11-27 Lundgren Mark A. Multiple field of view telescope

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9217671B2 (en) 2009-09-01 2015-12-22 Koninklijke Philips N.V. High spectral resolution color sensor using non-dispersive elements
US11221468B2 (en) * 2013-12-20 2022-01-11 Thales Optical imaging module having a hyper-hemispherical field and controlled distortion and compatible with an outside environment
US20180100996A1 (en) * 2016-10-10 2018-04-12 Northrop Grumman Systems Corporation Compact, simultaneous dual field of view through a common aperture
US10678035B2 (en) 2016-10-10 2020-06-09 Northrop Grumman Systems Corporation Compact, simultaneous dual field of view through a common aperture
US11428915B2 (en) 2016-10-10 2022-08-30 Northrop Grumman Systems Corporation Compact, simultaneous dual field of view through a common aperture
US20240369814A1 (en) * 2018-06-27 2024-11-07 The Charles Stark Draper Laboratory, Inc. Multiple Effective Focal Length (EFL) Optical System
CN114895447A (zh) * 2022-04-29 2022-08-12 中国科学院长春光学精密机械与物理研究所 一种共口径多视场红外光学系统

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