General Electric Company

Martin Marietta Corporation

United States of America As Represented by the Secretary of the Air Force

Milton L Noble

Albert F Milton

Robert W Yanka

William G Hoefer

Bryan L Cleaveland

John M Swab

Douglas W Dietz

Samuel E Craig

James B MacHaffie

Howard P Steiner

Darrel W Endres

A dual band IR scanning focal plane assembly includes two linear detector arrays in a close spaced configuration monolithically integrated on a common substrate. A medium wave IR staggered element linear array is formed on the front (111)B face of a (111) crystallographically oriented CdZnTe substrate in an MCT layer deposited by the molecular beam epitaxial (MBE) process. A long wave IR staggered element linear array is formed on the back (111)A face of the substrate in an MCT layer deposited by the liquid phase epitaxial (LPE) process. The sets of odd and even rows of the LWIR array on the back face are contiguous, while the sets of odd and even rows of the MWIR array on the front face are close-spaced, the spacing being just wide enough to allow a clear optical path to the underlying linear LWIR array. The arrangement provides simplified spectral separation of the simultaneously readout MWIR and LWIR images.

Dual-band IR scanning focal plane assembly having two monolithically

A compact dual band IR focal plane assembly provides simultaneous, coincident two-dimensional image readout. It includes a MIS-CID MWIR detector array formed in an epitaxial layer grown by the MBE process on the (111B) front face of an IR transparent crystalline first substrate, the pixels thereof forming LWIR transparent windows, with opaque connections thereto lying in aisles framing the windows, and a PV diode LWIR detector array formed in an epitaxial layer grown by the LPE process on the (111A) back face of the substrate, the LWIR pixels being aligned with the transparent MWIR pixels. An MWIR MUX is provided on an IR transparent silicon second substrate arranged in front of the first substrate. The opaque switch portion of the MWIR MUX is arrayed with apertures and aisles in alignment with the windows and aisles of the MIS-CID array. An LWIR MUX is provided on a third substrate bonded to the LWIR detector array beyond the image paths, the MWIR and LWIR MUXes providing simultaneous, coincident image readout.

A-dual band IR sensor having two monolithically integrated staring

An improved cold shielding arrangement for a scanned linear IR detector array normally having the pixels arranged in plural columns, is disclosed. The arrangement consists of a first slotted cold shield plate spaced from the array and designed to reduce the angular field of view for all pixels of the array in the scanning direction, and a composite cold shield in proximity to the individual pixels. The first part of the composite cold shield is a thicker plate, typically several mils thick having slots oriented to reduce the angular field of view in the resolution direction for the pixels in a common row. The second part of the composite cold shield is a thinner, top plate providing small apertures which further define the angular field of view in the resolution direction, and in certain cases also define the angular field of view in the scanning direction The first part of the composite cold shield may be fabricated of oriented silicon which may be preferentially etched to form small slots with vertical walls, while the second part of the composite cold shield may also be of silicon (typically 1 mil thick) with an opaque coating with photolithographically patterned apertures in a low reflectance, optically black film.

Cold shield for a scanned linear IR detector array

The invention relates to an improved IR imaging system for detecting a target producing an IR signature obscured by an ambient IR background. The imager comprises an objective lens, preferably of a telecentric design, and an area IR detector array. Two narrow wavebands are selected by an unpatterned bandpass filter, and a two part patterned filter, one part a long pass filter and the other part a short pass filter, installed close to the IR detector array. This choice permits the patterned filters to be quite thin, and more readily formed into smaller elements allowing increased image resolution. The use of a telecentric objective lens and the use of filters having higher average indices of refraction permit a wide field of view without compromising filter operation from filter wavelength shift.

Infrared imager forming two narrow waveband images of the same object

A high-resolution radiation detector cell array has a planar substrate, with multiple switching circuits, interposed between a detector substrate and a subsequent substrate containing high-sensitivity preamplifiers; each of the middle-substrate switching circuits operates to substantially continuously connect cyclic different ones of an assigned different set of the array cells to an associated single one of multiple preamplifiers. In a N.times.M array of cells used with a C column-by-R row switching subassembly, a total array of (N/C).times.(M/R) preamplifiers are needed. The generally-planar detector, switch and preamplifier substrates can be connected using metallic 'bump' contacts; the switch layer material may be selected to have a CTE between the CTEs of the detector and preamplifier layers.

Optical radiation sensing assembly with increased resolution

The invention relates to a cold shielding arrangement for use with either an individual staggered element linear IR array or a staggered arrangement of a plurality of such arrays. The cold shielding arrangement consists of a slitted plate spaced from the arrays, each slit being arranged to restrict the field of view of the pixels in both columns of one array in the scanning direction, and a pair of interdigitated pixel level cold shields set on the surface of each array to restrict the field of view of the pixels in the resolution direction.

IR sensor for a scanned staggered element linear array having improved

The invention relates to an imager for simultaneously obtaining two images of differing color bands of the same object field using a single two dimensional photodetector array. A Fresnel-biprism with two different color filters on the respective left and right aperture halves convergently displaces the two images. An objective lens focuses the filtered convergent images upon a photodector array, the left and right halves of which are covered by a second filter pair. The second pair of filters pass the same color bands as the first pair of filters but the order of the color bands bands is reversed from left to right. As a result of the filtering and convergence, the photodetector array, aligned with its columns parallel to the filter boundaries, responds with its left half to one color image and with its right half to the other color image. The arrangement provides two color band operation without resorting to a second photodetector array, or duplicate read out electronics, and when used in the IR spectrum avoids the need for additional cryogenic apparatus.

Imager for simultaneously obtaining two images of differing color bands

A dither scanned IR imaging system is disclosed for achieving panoramic coverage. For complete 360.degree. azimuth coverate, the field of view is divided into eight sectors, each imaged by a separate objective lens upon a loose packed 2D photodetector array. The photodetectors are tight packed in the array columns while the columns are loose packed, being on centers spaced by integral numbers of photodetector dimensions (i.e., pixels). The image is dithered the distance between columns over the array by a pair of counter rotating IR refractive discs of wedge shaped cross section. A full-frame partial-sample of the image is taken each time the image advances one pixel until the image has been fully sampled. Tight packed arrays may also be employed if additional means are provided to partially sample the image. In achieving 360.degree. panoramic coverage, the imaging system provides a major improvement in performance over systems using a single linear array and avoids large mirror movements or large gimbal movements. An approach for employing a conventional tightly packed two dimensional photodetector array in a dither scanned imaging system is also disclosed which uses fiber optics to transform the image plane to the required loosely packed partially sampled configuration. Used in this manner the area array covers a wide field of view with many more pixels of resolution than the number of photodetectors provided in the array.

Dither scanned IR imaging system having a wide field of view

A hybrid interconnection structure is disclosed having application to the fine pitch interconnection of delicate semiconductor chips. The invention entails the use of a beam lead interconnect in which patterned conductor runs are provided on the upper surface of a silicon chip. The conductor runs extend beyond the chip to form a paired set of beam leads. One set of beam leads makes contact with terminals on the upper surface of one chip and the other set of beam leads makes contact with terminals on the upper surface of another chip. The interconnect chip is set on a substrate common to the interconnected chips with its top surface slightly (normally less than 1-2 mils) above the top surfaces of the interconnected chips. This limits any downward deformation of the beam leads in the bonding process to insure reliability of the bond for fine pitch application. The invention has specific application to arrays of infrared detectors in which interconnections are provided between a delicate light sensing chip of mercury cadmium telluride or indium antimonide and more rugged readout integrated circuits, usually of silicon.

Hybrid interconnection structure

The invention relates to a high performance optical system for a wide angle IR imager requiring a cryogenic environment for the IR detector array. The wide angle requirement makes it necessary for one lens to be behind a 'cold aperture' within the cryogenic environment where focusing is difficult and performance of the aperture reduced. These objectives are minimized by use of a telecentric lens pair, one member of which is within the cryogenic environment. The telecentric lens pair refocuses the primary image formed by an objective lens, permitting a high quality image to be formed on the IR detector array. The usual errors in positioning the internal lens, which might impair the quality of the focused image, are avoided by a compensatory repositioning of the externally accessible objective lens. The use of collimated bundles of light, characteristic of telecentric lens pairs, permits maximum aperture efficiency, and also provides a fourier transformation plane in which spatial filtering may be used to reduce IR background of low spatial frequency.

Optical system for wide angle IR imager

The invention relates to an electron discharge device in which radio frequency energy is generated or amplified by high speed electrons traveling in a beam along the axis of a waveguide and subjected to a periodic magnetic field. The periodic field causes the electrons to travel in periodic orbits producing electromagnetic energy. When suitably adjusted, the energy in the beam is converted into electromagnetic energy of a given frequency. The device herein disclosed has an improved magnetic structure for causing the beam to travel in a helical path and for focusing it as it pursues this path. The helical path is produced by a static, spatially circularly polarized transverse field. Focusing of the beam is achieved by a pair of similar helically disposed axial magnetic fields having mutually opposite polarization. The fields are created by a plurality of short permanent magnets with cooperating pole pieces for directing the magnetic fields into the waveguide, and disposed in four rows arranged about the perimeter of the waveguide.

Electron discharge device with a spatially periodic focused beam

A scan corrected vidicon camera apparatus utilizing a spatial reference filter with an array of slits that is fitted directly on the faceplate of a vidicon tube. The spatial reference filter is used in conjunction with perturbations that are injected into the vertical and horizontal sweeps. The resultant video waveform is correlated in a microprocessor unit to linearize the respective sweeps.

Scan corrected vidicon camera apparatus

The present invention relates to a phase corrected raster scanned light modulator in which information modulated on a carrier is used to form a grating whose spatial frequency along the scanning line varies in accordance with the signal modulation frequency. Thickness variation in the medium on which the grating is formed causes an undesired phase modulation of the light which may be corrected by altering the carrier frequency. A novel oscillator is described which may be stepped discontinuously in frequency while the waveform and its slope remain continuous, which is of sufficient accuracy and agility to provide a real time region by region phase correction of the raster in the light modulator. The variable frequency oscillator is of high stability and can step from one value to another for intervals as short as one microsecond.

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Liverpool, NY, United States of America

Milton L Noble