US3427104A

US3427104A - Optical plural channel signal data processor

Info

Publication number: US3427104A
Application number: US26916A
Authority: US
Inventors: Wendell A Blikken; Louis J Cutrona; Arthur L Ingalls; Emmett N Leith; Leonard J Porcello
Original assignee: United States Department of the Air Force
Current assignee: United States Department of the Air Force
Priority date: 1960-05-04
Filing date: 1960-05-04
Publication date: 1969-02-11
Anticipated expiration: 1986-02-11

Description

Feb. 11. 1969 w. A. BLIKKEN ETAL OPTICAL PLURAL CHANNEL SIGNAL DATA PROCESSOR Filed m 4. 1960 Sheet I of 4 Fig-E3.

hVV'NIORS BY A 1969 w. A. BLIKKEN ETAL OPTICAL PLURAL CHANNEL SIGNAL DATA PROCESSOR Sheet '3 or 4 Filed lay ,4. 1960 INVENTORS WENDELL A. BLIKKEN guls J. CUTRONA A HUR 1.. lNGALLS EMMETT N. LEITH LEONARD J. PORCELLO BY M1...

ATTORNEY Feb. 11, 1969 w, BLJKKEN E'Q 3,427,104

' OPTICAL PLURAL CHANNEL smmu. mm rnocnssoa Filed May 4. 1960 Sheet 3 of 4 INVENTORS WENDELLA. BLIKKEN LOUIS J. CUTRONA ARTHUR L. INGALLS EMMETT N. LEITH LEONARD J. PORCELLO Feb. 11, 1969 w. A. BLIKKEN firm. 3,427,104

OPTICAL PLFJRAL CHANNEL SIGNAL DATA PROCESSOR Filed Bay 4. 1960 Sheet 4 014 INVENTORS WENDELL A. BLIKKEN LOUIS J. CUTRONA ARTHUR L. INGALLS EMMETT N. LEITH LEONARD J. PORCELLO ATTOR EY Wyml AGENT United States Patent 3,427,104 OPTICAL PLURAL CHANNEL SIGNAL DATA llA.Blikk m fi is! Cuts-one d wcnde en, H e an Arthur L. ln'galls, Ann Arbor, Emmett N. Leith, Plymouth, and Leonard J. Porcello, Ann Arbor, Mich assignors to the-United States of America as represented by the Secretary of the-Air Force vFiled May 4. 1960, Ser'. No. 26,916 U.S. Cl. 355-2 10 Claims Int. Cl. G03b 27/00, 27 /32, 27/68 This invention relates to a device for simultaneously processing wave trains in a great number of channels; wherein the wave trains in the various channels need not all be the same.

One object of the invention is to provide a device which processes Doppler frequency target information for all ranges simultaneously from information obtained from an airborne coherent side-looking radar.

Another object is to provide a device to produce desired compressed signals simultaneously in a great many channels from signals greatly dispersed in time or space by the use of optical techniques with noise and undesired signals greatly reduced.

These and other objects will be more fully understood from the following detailed description taken with the drawing, wherein:

FIG. 1 is a diagrammatic illustration of radar target information with targets separated in azimuth such as would appear on a film obtained from the recording unit of an air-home coherent'side-looking radar;

FIG. 2 is another diagrammatic illustration of radar target information with targets separated both in azimuth and range;

FIG. 3 shows the target information of FIG. 1 as it will appear on a film strip after processing in the devic of the invention;

FIG. 4 shows a three-dimensional view for a basic optical processor according to the invention;

FIG. 5 shows the optical system for the device of FIG. 4 for resolving target information in the azimuth direction;

FIG. 6 shows the optical system for the device of FIG. 4 for resolving information in the range direction;

FIG. 7 shows a modification of the device of FIG. 4 for providing compensation for changes of focus with range;

FIG. 8 is a schematic showing of the reference mask used in the device of FIG. 7;

FIG. 9 shows the relative motion of the first order images as the film is moved;

FIG. 10 shows a modification of the device of FIG. 7 which provides another method for providing range compensation:

FIG. 11 shows another modification for providing range compensation. I

The radar used to obtain the information as represented in FIGS-land 2 is a coherent radar, that is, it provides phase as well as amplitude information on all received radar signals by comparison with a stable reference oscillater. As the radar is carried along by the aircraft, a radar pulse is transmitted and the amplitude and phase of the returning signals from all targets are stored by recording on film. A short distance later another'pulse is transmitted and the return signals are againreoorded on the film. Continuing in this fashion the radar phase and amplitude history for each radar illuminated target is obtained over an extended distance of travel of the aircraft. All

of the phase information for each target adds-up to produce the'Doppler history for each target from. the time it enters the radar beam until" it leaves the radar beam.

This information can be used to give an improved resolution in azimuth.

The processing program in azimuth, however, is a function of range so that one needs a large number of computiug channels,each having the required computer program for each particular range. The various range increments may then be assigned to the appropriate computer channels. To avoid the construction of many channels, a single channel may be provided to scan all of the required programs sequentially in synchronism with the corresponding data for the different ranges. This system requires a large bandwidth, a scanning system and a data storage system. Either of these systems constructed on an electronic basis will involve a great amount of equipment and therefore a great cost. According to this invention, an optical data processing system is used which processes the Doppler frequency target information for all ranges simultaneously.

The operation of the system (for a given range) can be described as a cross-correlation of the signal with reference function which is a replica of the expected return from that range, the expected return having a form determined by the geometry of the radar antenna-target relation. Alternatively, the operation of the system can be described in terms of optical properties of the recorded signals. A recorded signal from a radar target is a substantially linearly frequency modulated record, which resembles a diffraction grating with grating spacing varying substantially linearly along its length, of a slice taken through a zone plate. Such structures have focal properties similar to those of a lens, as likewise does the recorded signal. When the signal history brings the impingent light to focus, the resulting image is the high resolution image which is sought. The signals have focal length which is a function of range to the target. The reference function described above is, from this viewpoint, a variable focal length lens which has a different focal length for each channel and compensates for the range variation of the signal focal length.

These two viewpoints are equivalent. However, some configurations are best described from one viewpoint, some from the other.

The simplest form of the invention consists essentially of a light source, a slit for providingcoherent illumination, a collimator, a signal film, a cylindrical lens, a photographic lens, an analyzer slit and a recording film. This simple form of the invention can be used only for a very limited range interval due to the change in focus with range. For a more extended range interval, means must be provided to correct for the change in focus.

Referring more particularly to FIGS. 1 and 2 of the drawing, which show a graphical representation of the Doppler histories of targets as they would appear on a strip of film from the recording unit of an air-borne coherent side-looking radar.

Reference numbers

21 and 22 in FIG. 1 show a graphical representation of the Doppler histories of two targets separated is azimuth. Reference direction. Thislight is passed through the

optical systems

33 and 34 through the final slit 35 in mask 36 and onto the recording film 37. The signal function appears on the film 38, which passes between

optical systems

33 and 34. Since the optical systems are different for range and azimuth: these systems will be described separately, with reference to FIGS. 5 and 6.

In the azimuth direction, shown in FIG. 5, the light from the narrow slit 30 is made parallel by collimator lens 33. This light is then brought toa distant focus by a signal on film 38. The distant image is then brought to focus on the final slit 35 bya camera lens 40. The recording film 37 may be placed very near the final slit 35 to receive the image. It is preferable, however, to provide a relay lens 41 to image the slit 35 on the film, as shown in FIG. 7.

In the range direction, the light from the line sourcev proceeds through lens 33 in the manner shown in FIG. 6 to illuminate the-signal film. The illustration of the light path in FIG. 6 is for only one range. A cylindrical lens 42 works together with the camera lens 40 to image the range elements from the signal film onto the final slit. In the range direction, the light source and first slit simply determine the amount of light allowed through the system and thereby determine the brightness of the image on the recording film. The astigmatie lens system 34 thus acts to integrate the signal in the azimuth direction while preserving the range information in-the range direction.

The speed of recording film with respect to the speed of the signal film is determined by the ratio of range reduction to azimuth reduction existing on the signal film. If 10.000 yards is shown as 35 mm..in the range direction, this same ratio should exist in the azimuth dimension so that the resulting image will be in proper proportion. However, the two ratios are not necessarily equal on the signal film, where, for example, 10,000 feet in azimuth might be represented as 700 mm., while 10,000 ft. in range might be represented as 35 mm. The equalization of the ratios is made by adjusting the speed ratio between signal film and recording film. For the example stated, the recording film should move ,4 the speed of the signal film in order to bring the image to proper portions.

The system thus far described can be used over a limited range interval only as the image goes out of focusdue to a change in focus with a change in range.

FIG. 7 shows one system, which may be used to com pensatc for changes of focus with range which is inherent in the signal recording. v

In the system of FIG. 7 reference numeral 50 refers to a light source which may be any type of light source, for example; a mercury vapor lamp. The light from light source 50 is imaged upon a slit 51 in mask 52 by means of a pair of

lenses

53 and 54. The width of slit 51 is determined by a compromise between image sharpness and total light intensity and, for the devices used, it has been between 20 microns and 250 microns. The length of the slit is not critical.

Between the

lenses

53 and 54 are provided a heat refleeting filter 55, to prevent heat from passing to the signal film and thereby damaging it, and an optical filter 56 to provide a monochromatic light for the data processor which, for the system built, was an optical green filter.

A lens 57. is provided to cause parallel light in the azimuth direction to impinge on thereference function mask 58, which will be explained in greater detail in connection with FIG. 8. Due to the difiraction etfectof the reference function, the distribution of light in the focal plane of lens 59 is a spectrum analysis of the spatial frequencies of the reference function. A slit 60 in. mask 61 is placed in the appropriate position in the focal plane of the lens'so that only the desired signals can proceed further along the system, as will be explained later. A lens 62 acts together with lens 59 to image-the reference function uponthe signal film 38. A weighting function filter 63, which consists of a variable. density filter which gradually decreases light transmission toward the edges of the reference mask, is provided for the same reason that antennas are tapered toward their ends which is to reduce side lobe efi'ects, as described at the bottom of page 452 and the top of page 453 of vol. 12 of the MIT Radiation Laboratory eries. The remainder of the system is the same as'FIG. 4.

vThe reference function on mask 58 the general configuration of which is shown in FIG. 8 consists-essentially of the ideal Doppler signal histories for tangets at all ranges of the radar and thus can be considered to have alike number of functions thereon corresponding to the functions on the signal film for all ranges of the radar. The spacings between the lines in the actual mask used are much less than as shown in FIG. 8. Since the time that a target appears in the radar beam will increase with range, thereference mask is wedge shaped.

The referencemask can be made in various ways. Two methods" have been used. First, the mask is drawn by hand and then reduced to size andplaced on a transparency by photographic means. Alternatively, a device used for ruling diffraction gratings has been used for producing the mask. In either case, the mask is only an approximation to the required'function, since the former is a two-valued function, being either transparent or opaque, while the latter is a continuous tone or shaded transparency. Specifically, the required referencefunction is of the form (+cos (x, y)), and the actual mask has the form The lack of continuous tone merely generates higher diffracted orders and these are removed by the mask 61 of FIG. 7. The reference mask contains thefrcquency terms only on one side of zero frequency.

As the signal history on the film 38 moves through the data processor, the image also moves. FIG. 9 illustrates the eti'ect of signal motion on the zero and two first diffracted order images. The first order images move in opposite directions, as shown in I-IG. 9, while the zero order image does not move. If signalfrequencies exist on only one side of the zero frequency, the first order images do not cross the zero order position, but fade out instead. The first order image that focuses short of the zero order image is called the first order positive image, since, with respect to this image, the signal history exhibits a positive focal length. The other first order image focuses beyond the zero order and this is called the negative first order image, since, with respect to this image, the signal history exhibits a negative focal length. Either the first order positive image or the first order negative image can be used for focusing on the output slit. Use can be made of the motion of the image to increase the exposure of the output film, by widening the output slit and choosing the proper camera lens to cause the motion of the first order image to correspond to the motion of the film.

Whichever first order image of the signal is used, the other first order image :Of the reference function is used. The negative first order image of the reference function compensates the positive first order image of the signal film, and the positive first order image of the reference function compensates the negative first order image of the signal film. The slit 60'is located in the proper position to select the required reference function image..The reference mask-thusbehaves as a lens with focal length equal to that of'the signal film focal length, but of opposite sign. Hence, targetsjfrom all rangcsare imaged at infinity by the referencefunction signal-film combination. The lens 40 brings this image in from infinity to the focal plane of the lens.

Other means for compensating for range requiring less equipment then shown in FIG. 7 is possible. FIG. 10 shows a system wherein a conical lens 70 is substituted for the reference function. With this system, the primary slit 51 is locatedoif'of the axis in the position of slit 60 of FIG. 7. The remainder of the system is the same as FIG. 7.

Another method of compensating for the change of focus with rangeisshown in FIG. II. The recording film and output slit could be slanted to compensate for the change of focus with range, however, a simpler method is to slant the mask containing the slit 51 as shown in FIG. 11. An additional cylindrical lens 71, and also a longer slit and light source, are needed-when slit 51 is slanted.

Still another system which could be used to-cornpensate for focus would be t0 provide an optical system to vary the wave length of the light used with range thereby producing 'a constant focus and perfect tracking at all ranges. I

The data processor was developed primarily to solve a specific problem in fineresolution radar. However, during the course of the investigation, a number of other applications were conceived. Withthe device of FIG. 7, the positions of the images on the mask 36 consist of a one-dimensional Fourier analysis of the spatial frequencies of the signal film 38. Thus, this portion of the system is a multi-channelspectrum analyzer.

The operation involved with the device of FIG. 7 is given by the following equation:

o, Misfits 21,010 w (1) In the special case described f(x, y) represents the reference function, g(x, y, t) represents the signal history and h(y, r), the output of the optical processor, rep resents the processed radar data.

Integrals of the form of Equation 1 occur for a number of cases, such as, high resolution radar, Fourier analysis, antenna pattern computation, cross-correlation, auto correlation, signal detection, biological correlation, signatureanalysis, analog computation and many others.

While the operation of the system has been described with parallel, or collimated, iightimpingent on certain elements, such as the reference function and conical lens, it is obvious that the device does not require coliimated light for. its operation, although the description, as well as the design, are facilitated by having collimated light at such positions. Likewise, the position of the signal film and reference function, or signal film and conical lens, can be interchanged. Numerous such variants are possible.

' Other functions, which the device of the invention is capable of performing by positioning of the slit in mask 61, are amplitude modulation detection, spectral analysis and filtering and frequency translation. It is obvious that there may be many other operations which can be performed with the apparatusof this invention.

The lens unit made up of

lenses

40 and 42 produces a one dimensional Fourier transformation between the plane of the film 38 and the plane of the mask 36, while preserving the other dimension for plural channel o eration. A number of such lens units can be placed in tandem to produce successive transformations with respect to one variable, while always preserving the variable of the other direction, namely, the vertical direction as the figures are drawn. At the successive planes wherein the successive transformations occur, additional transparencies representing functions can be placed. There ,fore, complicated system'transfer functions can be gencrated. Let the functions at successive planes be labeled f, a, b, c etc., where I is regarded as the. input signal and a, b, c produce an overall system transfer function. Let T(p) be the one dimensional Fourier transform of p. Then, the light distribution at successive planes, after the light is transmitted by the'transparencies of the plane, is p v tion and is the variable generated by the Fourier transformatlon.

While certain arrangements of the elements have beenv shown, it is to be understood that other arrangements might be used. For example, filters 55 and 56 need not be in the position shown, but may 'be located wherever there is parallel light in the azimuth direction; however, filter 55 must be located between the light source and the signal film. Lens 42 may be located behind slit 35 adjacent relay lens 41, but its axis must be rotated degrees with respect to its position as shown in FIG. 4. 7 Thereis thus provided a device for simultaneously processing wave trains in a great number of channels simultaneously.

We, claim: a l. A device for obtaining the integrated product 0 .two functions in a plurality of channels simultaneously, comprising: a first transparency having thereon a plurality of spatial'frequency functions with the functions extending in a first direction and the separate channels extending in a second direction perpendicular to said first direc tion, means for illuminating said first transparency with monochromatic coherent light which is collimated in said first direction, a second transparency having a plurality of functions extending in said first direction with the separate channels extending in said second direction, a pair of lenses for imaging said first transparency upon said second transparency, a first mask in the focal plane of the first lens of said pair of lenses, said mask having a'slit in the position of at least one of the first diffracted order images of said first transparency, a second mask, output means adjacent said mask, means for integrating the output of said second transparency in said first direction and for focusing said output on said mask, said mask having an output slit therein in the position of one of the first diffracted order images of said second transparency and means including said last named means for imaging the information in the separate channels in said second direction on said slit.

2. A device for obtaining the inte rated product of two functions in a plurality of channels simultaneously, comprising: a first transparency having thereon a plurality of spatial frequency, functions with the functions extending in a first direction and the separate channels extending in a second direction perpendicular to said first direction, means for illuminating said first transparency with monochromatic coherent light which is collimated in said first direction, a second transparency having a plurality of functions extending in said first direction with the separate channels extending in said second direction, a pair of lenses for imaging said first transparency upon said second transparency, a first mask in the focal plane of the first lens of said pair of lenses, said mask having a slit in the position of the first positive diffracted order image of said first transparency, a second mask, output means adjacent said mask, means for integrating the output of said second transparency in said first direction and for focusing said output on said mask, said mask having an output slit therein in the position of the first negative diffracted order image of said second transparency, and means including 'said last named means for imaging the information in the separate channels in said second direction on said slit.

3. An apparatus for processing a signal film, from an airborne coherent side-looking radar, having thereon Doppler frequency azimuth target information along the length of the film and range information across the film,

comprising: a signal film, means for producing a beam 'the light in the azimuth direction, a second mask having anoutput slit therein, output means adjacent said output 'slit, a'first'leu's for integrating the light information from said signalfilm inthe' azimuth, direction and for focusing it on said slit," a'second lens which together with said first tionwith the range direction being parallel to the line of light, -a reference transparency between said light source and said film, said reference transparency having thereon a signal for all ranges representing the ideal Doppler frequency history for targets at all ranges of said radar, means located between said first mask and said reference transparency for collimating the light in the azimuth direction, a heat reflecting filter and a monochromatic filter between said light source and said signal film, means for collimating the light passing through said heat reflecting filter and said monochromatic filter, a pair of lenses for imaging said reference transparency on said signal film, asecond mask in the focal plane of the first of said pair of lenses, said second mask having a slit in the position of at least one of the first diffracted order images of said reference transparency, a third mask having an output slit in the position of one of the first diffracted order images of said signal film, output means adjacent said output slit, means located between said signal film and said third mask for integrating the light information from said signal film in the azimuth direction and for focusing it on said slit, and

means for imaging the range information from said sig nal film on said output slit.

5. An apparatus forv processing a signal film from an airborne coherent side-looking radar, having thereon Doppler frequency azimuth target information along the length of the film and range information across the film, comprising: a signal film, a first mask having a narrow elongated slit therein, means for illuminating said mask to thereby produce a thin line light source, means for moving said film through said light in the azimuth direction with the range direction being parallel to the line of light, a reference transparency between said light source and said film, said reference transparency having thereon a signal for all ranges representing the ideal Doppler frequency history for targets at all ranges of said radar, means located between said first mask and said reference transparency for collimating the light in the azimuth direction, a heat refiectingfilter and a monochromatic filter between said light source and said signnl film, means for collimating the light passing through said heat reflecting filter and said monochromatic filter, a' pair of lenses for imaging said reference transparency on said signal film, a second mask in the focal plane of the first of said pair of lenses, said second mask having a slit in the position of at least one of the first diffracted order images of said reference transparency, a third mask having an output slit therein, a recording film, means for moving said recording film past said output slit, means located'between said signal film and said recording film for integrating the light information from-said signal film in'the azimuth direction and for focusing it on said slit, said slit being in the position of one ofthe first.diffracted order imsgesof said signal film and means for imaging the range information, from said signal film on said output slit.

6. An spparatus for processing a signal fllmfrom an airborne coherentside-looking radar, having thereon Doppler frequency azimuth target information along the length ofthe film and range information across the film,

comprising: evsignal film, a first mask having a'narrow elongated slit therein, means for illuminating said'mssk to thereby produce a thin line light source, means for moving said through said light in the azimuth direction with the range-direction being parallel to the line of light, a reference transparency between said light source and said film, said reference transparency having thereon a signal for all ranges representing the ideal Doppler frequency history for targets at all ranges of said radar, means located between said first mask and said reference transparency for collimating the light in the azimuth direction, a heat reflecting filter and a monochromatic filter between said light source andsaid signalfilm, a pair of lenses for imaging said reference transparency on said signal film, a second mask in the focal plane of the first of said pair of lenses, said second mask having a slit in the position of the firstpositive diffracted order image of said reference transparency, a third mask having an output slit therein, a recording film, means for moving said recording'film past said output slit, an astigmatic lens system located between said signal film and said recording film, said lens system having a first lens therein for inte grating the light information from said signal film in the azimuth direction and for focusing ,it on said slit, said slit being in the position of the first negative diffracted order image of said signal film, said lens system having a second lens which together with said first lens images the range information of said signal film on said output slit.

7. An apparatus for processing a signal film from an airborne coherent side looking radar, having thereon Doppler frequency azimuth target information along the length of the film and range information across the film, comprising: a signal film, a first mask having a narrow elongated slit therein, means for illuminating said mask to thereby produce a thin line light source, means for moving saidsfilm through said light in the azimuth direction with the range direction being parallel to the line of light, 'a reference transparency between said light source and said film, said reference transparency having thereon a signal for all ranges representing the ideal Doppler frequency history for targets at all ranges of said radar, means located between said first mask and said reference transparency for collimating the light in the azimuth direction, a heat reflecting filter and a monochromatic filter between said light source and said signal film, a pair of lenses for imaging said reference transparency on said signal film, a second mask in the focal plane of the first of said pair of lenses, said second mask having a slit in the position of the first negative diffracted order image of said'reference transparency, a third mask having an output slit therein, a recording film, means for moving said recording film past said output slit, an astigmatic lens system located between said signal film and said recording film, said-lens system having a first lens therein for integrating the light information from said signal film in the azimuth direction and for focusing it on said slit, said slit being in the position of the first positive diffracted order image of said signal film, said lens system having a second'lens which together with said first lens images the range information of said signal film on said output s it.

8-. An apparatus for processing a signal film from an airborne coherent side-looking radar, with the film having thereon Doppler-"frequency azimuth target information along-the length of'th'c film and range information across the film, comprising: a signal film, means for producing a beam ofmonochromstie light, means for moving said film through said light in the azimuth direction, a first maskhaving a slit therein located between said light beam" producing means and said film, said slit being narrowin the azimuth direction and elongated in the range direction, a reference transparency with a signal thereon corresponding to the ideal Doppler frequency for all ranges, located between said first mask and said signal film, means located betweensaid firstmask and said reference transparency for collimating the iight'in the azimuth direction, a pair of lens for imaging the reference functiomupon said signal film, a second mask located in the focal'plane of the first of said pair'of lenses, said second maskhaving a slit in the position of at least one of the first diffracted order images of said reference transparency, a recording film, a third mask adjacent said film, means for moving said recording film past said third mask, a first lens for integrating the light information from said signal film in the azimuth direction and for focusing it on said third mask, said third mask having a slit therein in the position of one of the first diffracted order images of said signal film, a second lens which together with said first lens images the range information from said signal film on said output slit.

9. An apparatus for processing a signal film from an airborne coherent side-looking radar, having thereon Doppler frequency azimuth target information along the length of the film and range information across the film, comprising: a signal film, a first mask having a narrow elongated slit therein, means for illuminating said mask to thereby produce a thin line light source, means for moving said film through said light in the azimuth direction, a heat reflecting filter and a monochromatic filter between said light source and said signal film, a conical lens located between said collimating means and said signal film to compensate for changes of focus with range on said signal film, means located between said mask and said conical lens for collimating the light in the azimuth direction, a recording film, a second mask adjacent said film, said second mask having an output slit therein, a first lens located between said signal film and said re cording film for integrating the light information from said signal film in the azimuth direction and for focusing it on said slit, a second lens which together with said first lens images the range information from said signal film on said output slit.

10. An apparatus for processing a signal film from an airborne coherent side-looking radar, having thereon Doppler frequency azimuth target information along the length of the film and range information across the film, comprising: a signal film, means for producing a beam of monochromatic light, means for moving said film through said light in the azimuth direction, a first mask having a slit thereinlocated between said beam producing means and said film to permit light to pass along a path through said film, said slit being narrow in the azimuth directon and elongated in the range direction, said mask being tilted with respect to said beam path in the longer dimension of said slit, means located'between said mask and said film for collimating the light in the azimuth direction, a cylindrical lens with its axis perpendicular to greater dimension of said slit located between said collimating means and said signal film, a recording film, a second mask adjacent said film, said second mask having an output slit therein, an astigmatic lens system located 1 between said signal film and said recording film, said lens system having a first lens therein for integrating the light information from said signal film in the azimuth direction and for focusing it on said slit, said lens system having a second lens which together with said first lens images the range information from said signal film on said output slit.

References Cited UNITED

Claims

1. A DEVICE FOR OBTAINING THE INTEGRATED PRODUCT OF TWO FUNCTIONS IN A PLURALITY OF CHANNELS SIMULTANEOUSLY, COMPRISING: A FIRST TRANSPARENCY HAVING THEREON A PLURALITY OF SPATIAL FREQUENCY FUNCTION WITH THE FUNCTIONS EXTENDING IN A FIRST DIRECTION AND THE SEPARATE CHANNELS EXTENDING IN A SECOND DIRECTING PERPENDICULAR TO SAID FIRST DIRECTION, MEANS FOR ILLUMINATING SAID FIRST TRANSPARENCY WITH MONOCHROMATIC COHERENT LIGHT WHICH IS COLLIMATED IN SAID FIRST DIRECTION, A SECOND TRANSPARENCY HAVING A PLURALITY OF FUNCTIONS EXTENDING IN SAID FIRST DIRECTION WITH THE SEPARATE CHANNELS EXTENDING IN SAID SECOND DIRECTION, A PAIR OF LENSES FOR IMAGING SAID FIRST TRANSPARENCY UPON SAID SECOND TRANSPARENCY, A FIRST MASK IN THE FOCAL PLANE