US Government As Represented by the Secretary of the Army

United States of America As Represented by the Administrator of Nasa

The United States of America As Represented by the Administrator of the

Vincent T Bly

Conrad W Terrill

Donna J Advena

Lynn E Garn

Anthony T Depersia

J Thomas Cox

Alan P Bradford

Lester F Gillespie

The present invention relates to a high resolution additive manufacturing method, including: creating a rigid shell of a stable material on all surfaces except for a sprue of a three dimensional (3D) polymer part using a chemical vapor deposition (CVD) process which includes: depositing the stable material at a process temperature of 100&#xb0; C. or less, and operating at, or near, atmospheric pressure; and removing the 3D polymer part by accessing the inside of the rigid shell through the sprue to allow dissolution of the 3D polymer part, thereby leaving a replicated rigid shell of the stable material.

High resolution additive manufacturing method with real materials

A method of making a mirror from a single crystal blank may include fine grinding top and bottom surfaces of the blank to be parallel. The blank may then be heat treated to near its melting temperature. An optical surface may be created on an optical side of the blank. A protector may be bonded to the optical surface. With the protector in place, the blank may be light weighted by grinding a non-optical surface of the blank using computer controlled grinding. The light weighting may include creating a structure having a substantially minimum mass necessary to maintain distortion of the mirror within a preset limit. A damaged layer of the non-optical surface caused by light weighting may be removed with an isotropic etch and/or repaired by heat treatment. If an oxide layer is present, the entire blank may then be etched using, for example, hydrofluoric acid. A reflecting coating may be deposited on the optical surface.

Method of making lightweight, single crystal mirror

This invention is directed to a process for manufacturing a lightweight mirror from a single crystal material, such as single crystal silicon. As a near perfect single crystal material, single crystal silicon has much lower internal stress than a conventional material. This means much less distortion of the optical surface during the light weighting process. After being ground and polished, a single crystal silicon mirror is light weighted by removing material from the back side using ultrasonic machining. After the light weighting process, the single crystal silicon mirror may be used as-is or further figured by conventional polishing or ion milling, depending on the application and the operating wavelength.

Lightweight optical mirrors formed in single crystal substrate

An infrared image is directed onto a transducer having a planar array of absorbing discs, on one side. The discs are supported by a thin membrane which sags or bulges as the discs heat up. The discs thus change their spacings with respect to a partially reflective mirror. The nominal spacing between the discs and mirror is about &frac14; wave-length of the infrared radiation, such that absorption is enhanced. The mirror is supported on a transparent substrate through which visible or near-infrared radiation is shown; the mirror/discs thus establish a Fabry-Perot cavity for this radiation, whereby a visible or near-infrared image may be observed or detected as the various discs establish various spacings in accordance with incremental variations in the infrared image. An alternate embodiment uses an electrostatic field to pre-bias the discs toward the mirror and thus to tune or adjuct the sensitivity of the transducer.

Uncooled far infrared thermal imaging system

A far-infrared image is directed onto a transducer having a planar array of absorbing discs on one side. The discs are supported by a thin membrane ich expands and bulges as the discs heat up. The discs thus change their spacing with respect to a partially reflective mirror. The nominal spacing between the discs and mirror is about 1/4 wavelength of the infrared radiation, such that absorption is enhanced. The mirror is supported on a transparent substrate through which visible or near-infrared light is shown, and carries a perforated mask atop an insulating layer and in registration with the discs. The mirror/discs thus establish a Fabry-Perot cavity for the visible or near-infrared light, whereby a visible or near-infrared image may be observed or detected as the various discs establish various spacings in accordance with incremental variations in the infrared image. An electrostatic field is established between the mirror and the shield by a voltage source. This field induces an electrostatic field in the discs to pre-bias the discs toward the mirror and thus to tune or adjust the sensitivity of the transducer.

Far infrared thermal imaging system

A unique structure for constructing the emissive patch of a spaceborne radiative cooler is shown. The structure has very high emissivity for all angles up to a designed-in maximum angle and near zero emissivity for greater angles. The structure also allows the use of high emissivity, nonconducting paints while fully complying with the NASA Electrostatic Discharge Susceptibility requirements for spacecraft. To accomplish these tasks, two previous disadvantages of prior art methods are addressed; eliminating background thermal radiation sources and problems concerning the high emissivity paints used in association with the black body radiator. A reflector consisting of an array of parabolic concentrators is separated from a black body element by an electrically conductive spacer. The concentrators serve to limit the field of view while the conductive spacer eliminates the need to use a conductive paint on the emissive element.

Patch for radiative coolers

Incident infrared radiation is focussed through a rotatable disk of germam onto a detector array. The disk has a thickness many times the wavelengths of the incident radiation and is partly covered with a pattern of germanium one-half wavelength of some preselected wavelength of the incident radiation. The pattern is a regular array of mesas, and acts as a phase grating which diffracts incident radiation. The diffracted (or blurred) image on the detector array is used as a reference level for background suppression.

Chopper for staring infrared systems

An infrared detecting system with a unique detector. The detector consists f an infrared-radiation absorbing layer on one side of thin-film substrate. On the other side of the substrate is a light reflecting layer, with a transducing material on the reflecting layer having a temperature-dependent index of refraction. Infrared radiation falling on the absorbing layer causes a temperature rise in this layer, a consequent rise in temperature of the reflecting layer and the transducing material, and a resulting change in refractive index of the material and a corresponding change in reflectance of the transducing material-reflecting layer combination. A read laser beam directed onto the material is thus reflected in accordance with the infrared radiation on the detector. Alternately, the reflecting layer may be on the same side of the substrate as the absorbing layer. Also, an additional reflector may be used between the reflecting layer and the transducing material.

Thermo-optical far infrared system

A sublimable layer is deposited on a substrate, holes are etched through sublimable layer, a thin-layer structure is deposited on portions of the remaining sublimable layer, and a thick structural support material is deposited to cover the sides and bottoms of the holes and portions of the thin-layer structure. When the sublimable layer is sublimed with the heat, photon enhancement (ultraviolet light) and oxygen purging, a structure is left which consists of a thin layer or layers supported by posts above a substrate.

Process for fabricating three-dimensional, free-standing microstructures

A dual focus objective lens and opposite linear polarizers associated therewith for providing a linearly polarized image at a first focal image plane and an opposite linearly polarized image at a second focal plane. A detector array is positioned at the first focal image plane which is closest to the objective lens. Each pixel site of the detector array has two halves with opposite polarities in each half wherein each half looks at opposite planes of polarization in the two image planes. One plane of polarization receives a focused linearly polarized image of the high spatial frequency target and low spatial frequency background and the other plane of polarization receives a slightly defocused image which contains a defocused image of the high spatial frequency target but a rather faithful reproduction of the low spatial frequency background. The two outputs from each half of the pixel sites are algebraically subtracted by processing electronics leaving a high contrast target image.

Passive optical system for background suppression in starring imagers

A twisted nematic liquid crystal optical, temporal bandpass filter device for transmitting optical images only having the time response near a given frequency. The device is comprised of two linear dichroic polarizers with orthogonal polarities at the input and output of the device and two twisted nematic liquid crystal light valves and a relay lens between the light valves. Each of the two light valves has a different time response and has opposite rotary direction handedness of the twist within the nematic liquid crystal cells. That is, the liquid crystal material in the cells is homogeneously aligned with 90.degree. twist between the front and back thin alignment insulator surfaces and the cells have counter untwisting of the polarized light. An a.c. voltage is applied across each cell with proper frequencies and proper liquid crystal cell thicknesses to insure that one of the light valves has a faster time response so that only the frequencies of the optical light image within the time based modulation of the faster cell but about the passband of the slower will be transmitted out the device since the slower cell has not counter twisted and cancelled the untwisting effect of the faster cell.

Optical, temporal bandpass filter

A technique for optical non-uniformity correction of a focal plane imaging ystem wherein incoming objective scene light rays impinging on each detector in a focal plane array is corrected on a pixel-by-pixel basis by optical correction means from a separate optical source. The optical correction means is comprised of a multiplicative correction means and an additive correction means. The multiplicative correction means is comprised of a responsivity mask positioned on or near the focal plane that provides a multiplicative factor of unity or less to each detector to cause more uniform sensitivity of the detectors. The additive correction means is comprised of the separate optical source that is positioned in a separate optical train and is comprised of an additive optical correction mask aligned with a light source and focusing screen means and image relay that relay the additive optical correction sensitizing illumination onto the focal plane array or the pixel-by-pixel basis. The additive correction may be used alone.

Technique for optical non-uniformity correction of an imaging system

A visible light absorbing and far infrared radiation emitting membrane is closed in an evacuated cell. The membrane consists of a thin insulating film coated with an optical black made from gold alloyed with a small percentage of nickel, copper or palladium. The gold alloy black is deposited in a soft vacuum inert except for a trace of oxygen.

Method of making visible light to far infrared transducer

The hydro-optical modulator has a purged and hermetically sealed thin liq cell with a working liquid throughout an enclosed sealed container that is in working contact with a pressure modulating system. The thin liquid cell is preferably a thin circular cell having windows on each side thereof where the optical radiation being modulated easily passes through the windows but is transmitted according to the size of bubbles in the working fluid. The size of the bubbles, and therefore the amount of optical radiation transmitted, is controlled by the pressure modulating system whereby smaller bubbles allow transmission while large bubbles scatter and limit transmission of optical radiation in an AC sensitive viewing device.

Hydro-optical modulator for modulating transmission of radiation

A high-quality dynamic far infrared image is produced by projecting a higuality visible image onto a unique transducer. The transducer consists of a very thin insulating film (approximately 500 A) with a thin coating of a good visible light absorber-far infrared emitter such as some metallic blacks.

Growing community of inventors

Alexandria, VA, United States of America

Vincent T Bly