United States Patent [19]
`McConkle et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,670,653
`Jun. 2, 1987
`
`[54] INFRARED DETECTOR AND IMAGING
`
`[57]
`
`ABSTRACT
`
`SYSTEM
`
`[75] Inventors: Charles C. McConkle, Corona;
`William F. O’Neil, Laguna Hills;
`Michael J. Meier, Diamond Bar;
`Thomas P- Fjeldsted, wesl COVma;
`JameS’L- Th?lltlasl, Placen?a; Afth'"
`F- Pfe'fer’ whmler: 3" of Calif‘
`[73] Assignee: Rockwell International Corporation,
`El Segundo, Calif.
`
`'
`[211 App!‘ NO" 767’582
`[22] Filed:
`Oct. 10, 1985
`[51] Int. Cl.4 ...................... .. H01L 25/00-G01T 1/22
`[52] us. 01. .................................. .. 250/330; 250/370;
`250/332
`[58] Field of Search ......... .. 250/330, 332, 334, 370 G;
`358/113
`
`[56]
`
`_
`References C'ted
`U.S. PATENT DOCUMENTS
`
`.
`
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`
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`
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`
`An lnfrared detector and lmagmg system responsive to
`the scanned image from an objective lens and scanner
`system, the infrared detector and imaging system com
`prising: a detector substrate; a sparsely populated stag
`gered detector array formed on the detector substrate,
`the detector substrate having a focal plane surface re
`ceiving the scanned image from the objective lens and
`Scanner System A Clock means Provides Clock Signals~
`A control signal means is responsive to the clock signal
`for providing a sequence of predetermined scanner
`position signals. A servo responsive to each scanner
`position signal commands the scanner means to locate
`the scanned image a‘ predetermined P°si“°"s 0“ ‘he
`f0?“ Plane; A detect“ signal integration, means re‘
`ce1ves and integrates an array of detector slgnals from
`"16 SParsely P°P111med_ detector arréy- A samPlmg
`means samples the amplltudes of each mtegrated signal
`from each image and digitizes each integrated signal
`amplitude to provide an array of digitized integrated
`detector signal values for each successive scanned im
`
`. . . .. 250/332
`4,039,s33 8/1977 Thom . . . . . .
`4,190,769 2/1980 Redman ............................ ._ 250/330
`Primary Examiner-—-Janice A. Howell
`Attorney, Agent, or Firm-H. Fredrick Hamann; George
`A. Montanye; James F. Kirk
`
`agc' A die“?! m?'l‘my means “mes ef'mh success“?
`array of dlgltlled Integrated detector Signal values 111
`corresponding image position memory locations.
`
`32 Claims, 22 Drawing Figures
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`U. S. Patent Jun. 2,1987
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`Sheet7 ofll
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`4,670,653
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`RELATIVE DETECTDR LUCATIEINia
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`U. S. Patent Jun. 2, 1987
`
`Sheet8 ofll
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`4,670,653
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`SEVEN SHIFTS USING DETECTOR ARRAY OF FIG. 10A
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`RELATIVE MEMORY LOCATIONS USED AFTER SEVEN SHIFTS USING DETECTOR
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`U. S. Patent
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`Jun. 2,1987
`
`Sheet 9 of 11»
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`4,670,65 3
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`U. S. Patent
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`Jun. 2, 1987
`
`Sheetll ofll 4,670,653
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`
`1
`
`4,670,653
`
`INFRARED DETECTOR AND IMAGING SYSTEM
`
`BACKGROUND OF THE INVENTION
`1. Field of The Invention
`This invention relates to the ?eld of multi-element
`electro-optic imaging systems and more particularly to
`a technique for increasing the resolution of infrared or
`thermal imaging system TIS (Thermal Imaging Sys
`tems) while preserving response time of the system.
`2. Prior Art
`Typical infrared or TIS operate by optically moving
`an image of a scene across a column of detectors.
`The response of a TIS is inherently limited by factors
`such as the number of detector elements present on the
`focal plane, the integration time, or time required by a
`detector element to produce a signal faithfully charac
`terizing the intensity of the sensed radiation, the time
`required to move the image, the separation space re
`quired between detectors on the focal plane to be eco
`nomically manufacturable, and the computational time
`to process the data from the focal plane.
`To increase the response of a TIS, early systems in
`creased the number of elements by using two dimen
`sional focal planes, providing a matrix of multiple detec
`tor elements. Each element images a particular portion
`of a scene. This technique, along with a technique for
`correcting the response from individual detectors is
`discussed in US. Pat. No. 4,298,887, issued Nov. 3,
`1981, titled NON-UNIFORMITY CORRECTION IN
`A MULTI-ELEMENT DETECTOR ARRAY, by J.
`P. Rohde, and assigned to the common assignee to this
`application.
`The individual detectors used to form the detector
`array are typically back biased semiconductor diodes
`that function as a current or voltage source when ex
`posed to incident light. Detector arrays are typically
`manufactured with constraints such as the minimum
`size.
`
`5
`
`35
`
`45
`
`SUMMARY OF THE INVENTION
`A principle object of the invention Infrared Detector
`Array is to provide a TIS having high resolution at low
`cost by use of a sparsely populated and easily manufac
`tured two dimensional detector array.
`It is a further object of the invention to fabricate the
`detector array on a detector substrate and to teach the
`fabrication of an array of integration circuits on a sepa
`rate substrate and to teach a novel means for coupling
`each detector to a respective integration circuit. The
`50
`coupling means permits reliably connecting very large
`numbers of detectors to respective integration circuits
`within a very small cryogenically cooled area.
`High resolution and low costs are realized by the
`invention of a sparsely populated detector array. The
`55
`sparseness of the array enhances the manufacturability
`of the invention by providing a sufficient amount of
`space on the substrate around each detector. The reso- ,
`lution of the system is then enhanced by using the same
`detectors to sample a large number of pixels of the scene
`while incrementally moving the focused image across
`the focal plane by the use of a scanner. The array of data
`obtained from each incremental snapshot of the moving
`image is stored in a digital memory.
`The sparse array of detectors is patterned into a novel
`arrangement of two arrays, the ?rst being referred to as
`the “A” array and the second, as the “B” array. Each of
`the two arrays is formed on the same substrate and is
`
`65
`
`2
`arranged to have identical patterns. The “B" array is
`positioned on the substrate to one side of the "A" array.
`In addition, rows of the "B” array are vertically dis
`placed to be on lines interposed between lines obtained
`by extending the centerlines of rows of the “A” array
`laterally.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a block diagram of the invention system
`arranged for use in a thermal sight system.
`-
`FIG. 2 is a front view of a prior art scanner with
`scanning wedges centered.
`FIG. 3 is a front view of a prior art scanner with
`scanning wedges displaced by cams.
`FIG. 4 is a side view of a prior art scanner showing a
`drive motor and also showing the wedge pivot and
`bearings in section.
`FIGS. 5a and 5b are drawings that relate the lateral
`motion of a scanned image to the relative angular mo
`tion of wedges A and B.
`FIG. 6 is a sectional view of the detector and integra
`tion cell substrate.
`FIG. 7 is a perspective view of an assembly showing
`the detector substrate in partial cut-away mounted via
`indium bumps to the multiplexer cell substrate.
`FIG. 8A is a schematic representation of the relative
`location of detectors in a four column A, B staggered
`array on four grid unit centers.
`FIG. 8B is a schematic representation of a portion of
`FIG. 8A submitted to show B1 detector array row
`locations interleaving A1 detector locations, and also
`showing left and right array displacements.
`FIG. 9A is a schematic showing the relative locations
`of detectors in two column A, B detector array on four
`grid unit centers, a single step stagger and also showing
`left and right array displacements.
`FIGS. 9B, 9C, 9D and 9E are schematic representa
`tions of relative memory locations in which a sequence
`of image data arrays are stored.
`FIG. 9F is a schematic representation of the respec
`tive pixel memory location, the full array of circles
`characterizing the relative memory locations in which
`detector image information is stored from 16 image data
`arrays positioned with 15 shifts.
`FIG. 10A is a schematic showing the relative loca
`tions of detectors in a two column A, B detector array
`on two grid unit centers, and a single step stagger.
`FIG. 10B is a schematic representation of the pixel
`locations on a video monitor’s screen, each circle also
`corresponding to a respective pixel memory location,
`the full array of circles characterizing the relative mem
`ory locations in which detector image information is
`stored from 8 image data arrays as the image is scanned
`across the detector array of FIG. 10A, the arrays being
`positioned with 7 shifts.
`FIG. 11 is a schematic representation of the pixel
`locations on a video monitor’s screen, each circle also
`representing a corresponding pixel memory location,
`the full array of circles characterizing the relative mem
`ory locations in which detector image information is
`stored from 8 image data arrays as the image is scanned
`across the detector array of FIG. 10A, expanded to 40
`detectors having columns Al-BS.
`FIG. 12 is a schematic representation of the logic
`circuit organization used for addressing respective inte
`gration cells.
`FIG. 13 is a schematic of an integration cell circuit.
`
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`4,670,653
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`FIG. 14 is a sequence diagram showing relative tim
`ing relationships.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`FIG. 1 shows a block diagram of the infrared detec
`tor and imaging system within phantom block 10. The
`system 10 receives a scanned image (not shown) fo
`cused on the flat surface 12 of detector array 14. The
`scanned image is projected onto surface 12 by scanner
`300 and objective lens system 200. The image on the
`surface of detector array 14 is formed from light re
`flected from object 100 in object space represented by
`rays 402 passing to objective 200, passing through ob
`jective lens 200 as ray 404, and then passing to scanner
`300 as ray 406. Scanner 300 periodically and recipro
`cally displaces all rays passing through it, such as ray
`408 and those leaving it such as ray 410 to form an
`oscillating focused image of the object 100 on the detec
`tor surface 12. Ray 410 passes through a calibration
`shutter and diffuser 500 interposed between scanner 300
`and the surface of detector array 14. Throughout this
`document the word “light" will be meant to include
`electromagnetic radiation in the infrared spectrum.
`US. Pat. No. 4,380,363, issued Apr. 19, 1983 and
`assigned to the common assignee teaches a Four Ele
`ment INFRARED OBJECTIVE LENS such as that
`characterized by block 200. U.S. Pat. No. 4,427,259
`issued Jan. 24, 1984 and assigned to the common as
`signee teaches an alternative objective lens.200, i.e. a
`,. SELECTABLE FIELD-OF-VIEW INFRARED
`’ LENS having a detachable afocal telescope and a four
`element reimager objective lens positioned between the
`scanner and the detector array. It is understood that
`con?gurations designed to position the scanner 300
`between the objective 200 and the detector surface 12
`. are functional equivalents to con?gurations designed to
`a position the objective 200 between the scanner 300 and
`I the detector surface 12. Several equivalent arrange
`ments are possible for placement of the calibration shut
`ter and diffuser 500 in relation to objective 200 scanner
`"300 and the detector array 14. The particular design
`objectives of an apparatus using the subject invention
`will dictate the arrangement selected.
`U.S. Pat. No. 4,502,751 dated Mar. 5, 1985 and as
`signed to the common assignee teach a LINEAR OP
`TICAL SCANNER functionally equivalent to scanner
`system represented by block 300. FIGS. 2, 3, 4, 5a, 5b,
`6A, and 6B show the scanner described in US. Pat. No.
`4,502,751 as having two wedge prisms driven by a pair
`of cams. The two prisms are driven thru a small angle
`transverse to the optical axis by cam lobes 306, 308.
`FIG. 4 shows a side view of the scanner 300 with motor
`302 being mounted in frame 303. The cam lobes 30,6, 308
`are rotated on motor shaft 304.
`FIG. 5a depicts the angular position of counter-rotat
`ing prisms A and B at times 1, 2 and 3. FIG. 5b charac
`terizes the lateral displacement of a light ray on the
`focal plane surface 12 from a center point (1) to position
`(2) and (3) as the prisms are counter-rotated to concur
`rent positions (1), (2) and (3).
`FIGS. 5a and 5b show the relative deflection of a ray
`on the focal plane in response to a partial oscillatory
`oscillation or rotation of the prism pair. The rotation of
`65
`the A and B prism is restricted to arcs of rotation of
`opposite sense or polarity having approximate magni
`tudes of plus and minus 30 degrees respectively. All
`
`4
`rays passing thru the scanner are de?ected as a bundle
`thereby de?ecting the image on detector array 14.
`FIG. 1 shows block 500 representing a shutter-dif
`fuser functional element. This element is functionally
`necessary for periodically calibrating the detector ar
`ray. When selected, the shutter-diffuser interrupts the
`light forming the focused image and provides a diffused
`and even source of light to all detectors comprising
`detector array 14. The presence of a uniform source of
`light simultaneously on all detectors makes it possible to
`calibrate the detector array by adjusting the bias or
`reference level for the detector array.
`Block 14 represents a detector array assembly con
`taining detector array 14. The detector array 14 is
`formed on a ?rst substrate. FIG. 6 provides a sectional
`view of two detectors in diffusion wells 20, 22 in detec
`tor array 14 below ?at focal plane surface 12 on sub
`strate 16. Substrate 16 is formed of CdTe (Cadmium
`Teluride) and is backilluminated. Substrate 16 is trans
`parent to light in the infrared spectrum of interest. The
`infrared light from object space is focused on ?at focal
`plane surface 12 to form an image, the light then passes
`through the substrate; as characterized by rays 24, 26, to
`reach the detectors in wells 20 and 22. The detectors are
`formed in layer 18 of I-IgCdTe (Mercury-Cadmium-'
`Teluride) on which a staggered array or pattern of
`bumps 48, 50 of Indium are deposited on metallurgical
`contacts 52 and 54. Contacts 52, 54 are electrically
`coupled to the detectors via metallurgical conductor
`patterns formed on the detector substrate using photoli
`thography, plating and etching techniques. Contacts 52,
`54 respectively, provide a low resistance contact to the
`cathodes of detectors 20, 22. The anodes of the detec
`tors are electrically common and are electrically cou
`pled via plated or metallurgical paths to an electrical
`contact similar to those represented by reference num
`bers 52 and 54.
`FIG. 6 also shows integration cell substrate 40 having
`dielectric layer 42 and metallurgical interconnections
`44 and 46. Bumps 56, 58 of indium are formed on electri
`cal contacts 44, 46, respectively, the location of the
`bumps on the integration cell substrate 40 being posi
`tioned to complement the location of the bumps on the
`base of the detector substrate.
`As the substrates are merged or pressed together, the
`bumps deform as shown in FIG. 6 reliably forming
`hundreds or even thousands of low resistance electrical
`contacts, each electrical contact applying a relatively
`uniform force to the cathode of the detector. Contact
`pressure in?uences the detector response, so the use of
`indium bumps as a coupling means makes it possible to
`mate large numbers of detectors in a detector array with
`other electronics without inducing substantial irregular
`ities due to variations in contact pressure near some
`diodes and not near others.
`The detectors 20, 22 in FIG. 6 are intended to repre
`sent only two detectors in a sparsely populated array of
`detectors such as the sparse array of detectors formed in
`detector substrate 16.
`Each detector in each array is located by coordinates
`that specify the row and column location of the detec
`tor center in relation to a reference system such as a pair
`of optical targets. Each detector has an effective view
`ing area surrounding its coordinate location or center
`that is functionally related to the size and sensitivity of
`the detector.
`For the purpose of illustrating the invention sparse
`array, refer to FIG. 8A. This ?gure is meant to schemat
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`ically represent the relative detector locations in rela
`tion to the reference detector 801 at location (0, 0).
`Table 1 below lists the absolute detector locations of
`a portion of one embodiment of a detector array mea
`sured in inches in "X” and “Y”~ coordinates. The 0, 0
`reference coordinate is at location x=0.000 and
`y=0.000 at the reference detector.
`TABLE 1
`Y
`
`a
`
`as
`
`X
`
`a a X
`
`Y
`
`6
`vertically positioned one uniform unit row or grid unit
`below the preceding column on the substrate. Each
`successive B1 (right) detector array column of detectors
`is also positioned to form a staircase-like pattern. The
`?rst detector such as 1,5; 1,6; 1,7 in each B1 array suc
`cessive column is vertically positioned one grid interval
`below the preceding column on the substrate.
`In an alternative embodiment, of the system of FIG.
`1, the scanner system provides a scanner position signal
`such as a digital encoder signal referencing the image
`position. In this embodiment, the clock means 412 is
`responsive to the scanner position signal (via an un
`shown path). The clock means is synchronized to the
`motion of the image on the focal plane by position sig
`nals from the scanner. In yet another alternative em
`bodiment, the scanner can be fabricated to provide a
`sequence of predetermined pairs of switch closures to
`send phase information for scan direction along with a
`start and limit signal. Between each signal from the
`scanner, the clock means is characterized to provide the
`clock pulses required to operate the CONTROL SIG
`NAL MEANS 414, THE ADDRESS SELECT
`MEANS 416, THE MEMORY MEANS 418 and the
`CONVERTER MEANS 422 via signal line 424. The
`scanner switch closures can be implemented using con
`ventional electromechanical switches, optical encoding,
`HALL-EFFECT devices or other magnetic or elec
`tronic switching means.
`In yet another alternative embodiment of the inven
`tion of FIG. 1, the scanner 300 is equipped with a scan
`ner position servo 424. The position servo in this alter
`native embodiment is fabricated to continuously drive
`the scanner to position the image on the detector array
`to a sequence of predetermined positions, each of the
`predetermined positions corresponding to a position
`signal from the CONTROL SIGNAL MEANS 414.
`One alternative embodiment includes a ROM in the
`CLOCK MEANS 412 or in the CONTROL SIGNAL
`MEANS 414 programmed to provide a recurrent series
`of image position locations to the POSITION SERVO
`424 via signal bus 426.
`The CONTROL SIGNAL MEANS 414 of FIG. 1 is
`responsive to the clock signal on bus 424 and to each
`scanner position signal for providing a sequence of
`array address signals for MEMORY MEANS 418.
`Each address signal within each array designates a
`memory location in which to store a digital value char
`acterizing the amplitude of the integrated signal from a
`respective detector.
`Each image array of data, when stored, is retrievable
`to form a sparse video image.
`FIG. 9A is a schematic representation of a two col
`umn, one step A, B array having detector elements
`spaced four grid units apart. For the purpose of illustrat
`ing the invention, detectors.802, 804, 806 and 808 are
`referenced. Each grid unit represents an image shift
`distance. The array is shown having 18 detectors in an
`A1, B1 and A2 array.
`At the ?rst image position, the eighteen detectors
`provide eighteen (18) signals via the COUPLING
`MEANS 600 (bumps) shown in FIG. 1 to eighteen
`integration cells on the integration substrate. In re
`sponse to signals from CLOCK MEANS 412 and CON
`TROL MEANS 414 and under control of ADDRESS
`SELECT MEANS 416, each of the eighteen integrated
`signals are coupled to CONVERTER MEANS 422 for
`conversion to digital values, the resulting eighteen digi
`
`1) 0.000.
`A. (l.
`2)
`.004.
`A. (l.
`3)
`.008,
`A. (l.
`A. (l. 4)
`.012,
`A. (2.
`l)
`.000.
`‘Readout Row
`" Readout Column
`
`0.000
`.00]
`.002
`.003
`.004
`
`I) 0.0155. 0.0005
`B. (l,
`2) 0.0l95. 0.00l5
`B. (l.
`3) 0.0235. 0.0025
`B. (l,
`B, (l. 4) 0.0175. 0.0035
`B, (Z,
`I) 00155, 0.0045
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`The sparse detector array of FIGS. 8A and 8B con
`tain at least one pair of left and right detector arrays.
`The embodiment of FIG. 8A shows a left array under
`the bracket designated as A1 and a right array under the
`center bracket designated as B1.
`Each detector array has at least a ?rst column of
`detectors spaced horizontally and vertically at uniform
`unit row intervals (D) on the substrate. The A1 array of
`FIG. SA has four columns of detectors designated as
`columns C1, C2, C3 and C4. The rows of the A1 array
`are designated as R1, R2, R3 and R4. The columns are
`shown to be spaced apart at uniform detector column
`intervals E.
`FIG. 8A shows that the number of columns in the A1
`(left) detector array is equal to the number of columns
`in B1 (right) detector array.
`FIG. 8B duplicates a portion of the array of FIG. 8A.
`Phantom lines 803, 805 and 807 are projected from
`detectors in the B1 array to the vertical reference axis
`820 along with solid lines 802, 804, and 806 from detec
`tors in the A1 array to permit FIG. SE to illustrate that
`the B1 array (right) column detectors in columns C5,
`C6, C7 and C8 are vertically positioned at row locations
`803, 805, 807 between the rows occupied by said left
`detector array 802, 804, 806 and 808. The B1 array is
`horizontally positioned to the right of the A1 (left)
`detector array at a right array displacement U on the
`substrate.
`FIG. 8B shows the right array displacement U to be
`three and one-half grid intervals. There are four grid
`intervals to each unit detector column interval E. Ar
`rays A1 and A2 are successive staggered left detector
`arrays. The left detector array A2, is horizontally posi
`tioned to the right of the preceding right detector array
`B1 at a left array displacement distance, V, at four and
`one-half image shift distances FIGS. 8A and 8B are
`scaled to make lateral image shift intervals equal to the
`image shift distances.
`The FIG. 8A, 8B embodiments are meant to show
`more particularly that the left array displacement V on
`the substrate is further characterized to be equal to a
`?rst number of image shift distances plus one-half of an
`image shift distance. The left array displacement V is
`four and one-half grid units, and the right array dis
`placement U on the substrate is further characterized to
`be equal to the ?rst number of image shift distances
`between columns in the left array minus one-half of an
`image shift distance, i.e., three and one-half grid units.
`The “A” (left) array of FIG. 8A, 8B is shown to have
`65
`detectors in successive columns such as C1, C2, C3, C4
`positioned to form a staircase-like pattern. The ?rst
`detector in each successive column in an A1 array is
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`tized values being then stored in respective locations in
`the video image obtainable from a given detector den
`sity or spacing is enhanced far beyond that obtainable
`the MEMORY SELECT MEANS 418.
`FIGS. 9B, 9C, 9D schematically represent the mem
`from a conventional staring system.
`Referring again to FIG. 10B, as the image is shifted
`ory locations of successive image data arrays on a mem
`for the seventh time on the focal plane the image pixel
`ory map. FIG. 9B represents a map of the ?rst array of
`memory locations 903, 905, 907, 909 in which the digi
`sensed by the upper left detector of the A1 column in
`the eighth data array is contiguous (i.e., adjacent) with
`tized integrated detector values from detectors 802, 804
`the data taken by the upper left detector of the A2
`and 806 and 808 are stored. FIG. 9B characterizes a
`second array of adjacent memory locations 1003, 1005,
`column taken with the ?rst data array before the ?rst
`1007 and 1009 adjacent to respective locations 903, 905,
`incremental image shift. If scanning continues after the
`907 909. These relative data locations are ?lled with
`seventh incremental shift and an additional shift in the
`data from the second image data array subsequent to a
`same direction is taken, the data taken via the upper left
`?rst shift of the image through a lateral image shift
`detector in the A1 column and its associated electronics
`will overlay and obscure the data taken by the upper
`distance on the focal plane and subsequent to a second
`integration interval. FIG. 9C maps additional memory
`left detector in the A2 column stored at the time the ?rst
`locations 1103, 1105, 1107 and 1109, each containing the
`array of data was taken.
`digitized integrated value from a respective detectors
`It is clear from this example, that care must be taken
`902, 904, 906, 908 obtained subsequent to a second shift
`to coordinate the detector size, in-scan-direction spac
`of the image through a lateral image shift distance on
`ing (FIGS. 9-11 show horizontal scan examples) and
`the focal plane and subsequent to a third integration
`the number of image shifts per scan to obviate image
`interval. FIG. 9D is a map of the data stored subsequent
`gaps or data obliteration. The distance through which
`to the third shift into locations 1203, 1205, 1207, 1209
`the image moves on the focal plan is a function of the
`scan angle controlled by the scanner and the objective
`and FIG. 9E is a maps the data into locations 1303,
`1305, 1307, 1309 after a fourth image shift. FIG. 9F is a
`lens system. Each incremental scan moves the image on
`map of the relative memory locations containing data
`the focal plane through an incremental shift distance
`for 16 image positions resulting from 15 successive
`equal to the effective width or size of the detector. The
`image shift distances on the focal plane.
`number of lateral incremental shifts required for a com
`The image data in cells 903 and 1003 originated from
`plete scan in one direction will, therefore, be equal to
`. the same detector 902 reading adjacent images. As the
`one less than the number of effective detector widths
`between adjacent corresponding A columns. For exam
`. data in these locations is row scanned, left to right or
`ple, referring to FIG. 10A, eight effective detector
`right to left, converted back to an analog signal, this
`a ' analog signal being used to modulate a video beam
`widths are shown between columns A1 and A2. Ob
`moving from left to right on the screen, the beam will
`serve that the indicated spacings are 2+2.5+2+ 1.5 and
`duplicate the image intensity at the two adjacent loca
`the sum equals eight.
`tions. The image array data in the memory map of FIG.
`FIG. 13 is a schematic of a single cell circuit capable
`9D, if row scanned and converted, provides a video
`of functioning in an array as a detector signal integra
`image of higher resolution.
`tion means 420 for receiving, and integrating an array of
`detector signals from the sparsely populated detector
`The map of FIG. 9F provides image data at the cen
`ter region designated by bracket Z having double row
`array 14.
`and double column density after ?fteen image shifts.
`Operation of the circuit of FIG. 13 will be explained
`The video image resulting from row scanning the Z
`in accordance with the timing chart of FIG. 14. In
`“ bracketed data provides a video image having a resolu
`response to infrared light rays, such as ray 410, detector
`tion of twice that obtainable from a detector array in
`D2 responds as a current source sourcing electrons onto
`which the detectors represented by circles, such as
`integration cell circuit input node 601. The electrons are
`coupled via coupling means 600, comprising indium
`those in FIG. 9A, were to be placed side by side, their
`circular edges being in contact with laterally adjacent
`“bumps”, shown in FIGS. 1, 6, 7 and discussed supra.
`detectors and with those above and below.
`The detector anode is coupled to a BIAS voltage source
`Referring to FIG. 9F, the data in the map represented
`604 referenced to reference node 612.
`by brackets X and Y is referred to as scalloped data.
`ZERO INTERVAL REF. VOLTAGE SOURCE
`606 is sampled periodically by each integration cell
`This data is not used in producing a uniform high res