Abstract: A charge-coupled imaging device (FIG. 3) is thinned to allow for backside illumination. The device is further enhanced using ion implantation techniques to establish an electrical field (44) at the back surface, which functions to drive free electrons to potential wells generated beneath a gate structure (40) on the front surface. The device structure allows for both front side and backside illumination and is useful as a imaging device in applications where it is necessary to combine images from two different optical sources. The imaging device is particularly useful in terrestrial guidance systems (FIG. 5) where the imaging device is used to detect guide stars from a large guide star field. In such systems, the imaging device must be translated within an X-Y plane in order to cover the entire guide star field. In order to accurately know the position of the imaging device, optical fiducial marks are imaged onto a side of the imaging device opposite the side receiving the guide star photons.

Abstract: A wavefront sensor (10) includes a radiation sensor (2) and an array (12) of lenslets (12A) that are optically coupled to the radiation sensor. The array of lenslets has a radiation receiving surface for receiving an incident wavefront and for focussing the wavefront at a plurality of focal positions upon the radiation sensor. Each of the lenslets comprises a diffractive optical element having an optical center that is located at a predetermined point for inducing an equal and opposite tilt to a portion of the wavefront incident on the lenslet. As a result, an aberration within that portion of the wavefront is cancelled. The predetermined point is determined to be equal to and opposite a focal spot shift of the lenslet.

Abstract: A method and system for calibrating color filters employed in polychromatic imaging of a subject includes a scanning mirror (28), telescope (30), filters (104), and a detector array (60) employed for both imaging and calibration processes. A bundle (44) of optical fibers is employed for producing a slit-shaped beam of solar rays which are collimated and applied to a diffraction grating plate (54) or prism (72) to produce a set of dispersed solar rays. The dispersion is based on color. In one position of the scanning mirror, rays from a subject (12) to provide an image are directed through the telescope and scanned across the filters (104) and detectors (102). In another position of the scanning mirror, the set of dispersed solar rays is scanned past the filters and the detectors. Imaging data outputted by the detectors is collected for producing an image (112) of the subject. Data of the dispersed rays is collected for calibrating the color filters.

Abstract: Optical metrology apparatus includes one or more first sample point interferometers (SPIs) (16) having a wide dynamic range for measuring a rigid body position of a surface of a structure, such as a segmented mirror (11). At least one second SPI (18), having a lower dynamic range, is employed for measuring a figure of the segmented mirror. Either the first or the second SPIs may also be employed to measure a lateral displacement between the mirror segments (11a, 11b). The use of multiple SPIs, having differing dynamic ranges, within a closed-loop mirror control system is also described.

Abstract: A method is provided for calibrating a beamline (24) used for X-ray lithography. The beamline includes an elongated evacuated tube (28) extending from an X-ray source (22) for containing the X-ray beam to a closure (32) at an opposite end including a beryllium window. A target wafer (34) aligned with, but external of, the tube is positioned in a plane transverse of the X-ray beamline and is coated with a uniform layer of light sensitive material. A carbon filter (31) intermediate the X-ray source and the target wafer is provided within the tube to block electromagnetic radiation having wavelengths generally in the region of ultraviolet, visible, and infrared ranges of the spectrum. The beam from the X-ray source is scanned through the beamline, through the filter, and onto the target wafer. Thereafter, the wafer is subjected to an etch process thereby forming a contoured surface (34A) emulating the non-uniformities caused by the components of which the beamline is comprised.

Abstract: An apparatus (10) for providing a consistent registration of a semiconductor wafer undergoing process work includes a platen (38) upon which a surround (14) is registered. The surround registers to the platen (38) by matching two pins (42), (40) that protrude from the platen (38) to a hole (44) and a notch (46) in the surround (14), respectively. A first registration surface (16) for registering a flat (20) of a semiconductor wafer (12) is permanently mounted to the surround (14). A second registration surface (18) for registering a point (24) on the circumference of the semiconductor wafer (12) is permanently mounted to the surround (14). A third, adjustable registration surface (26) also registers to a point (28) on the circumference of the wafer (12). This third registration surface (26) is springloaded to accommodate for slight diameter variations in successively processed semiconductor wafers, and to provide a force to hold the wafer (12) in place.

Abstract: A monochromator 18 has a thin faceplate which reduces temperature-induced distortion in a strain-free region by placing it close to a two-level heat exchanger 46, 64. The heat exchanger has a first level 46 in juxtaposition with the faceplate 22 for efficient heat extraction, and a second level 64 which establishes a constant temperature plane along a neutral bending axis of the monochromator 18. The first level heat exchanger is operated at a temperature below the zero CTE point of the silicon faceplate so that the integrated CTE of the faceplate is approximately zero. Pumps 30 and 32 are disposed respectively at the coolant inlets 26 and outlets 28 for fine-tuning the coolant pressure so that a minimal pressure across the faceplate 22 may be established to minimize bending moments on the thin faceplate.

Abstract: A standard thick silicon charge-coupled device (FIG. 1A) has its pixel face mounted to a transparent, optically flat glass substrate using a thin layer of thermoset epoxy. The backside silicon of the charge-coupled device is thinned to 10 .+-.0.5 um using a two-step chemi-mechanical process. The bulk silicon is thinned to 75 um with a 700 micro-grit aluminium oxide abrasive and is then thinned and polished to 10 um using 80 nm grit colloidal silica. Access from the backside to the aluminum bonding pads (36 of FIG. 5) of the device is achieved by photolithographic patterning and reactive ion etching of the silicon above the bonding pads. The charge-coupled device is then packaged and wire-bonded in a structure which offers support for the silicon membrane and allows for unobstructed backside illumination.

Abstract: Optical metrology method and apparatus wherein three optical wavelengths of a fixed polarization are generated and separated into a reference beam (RB) and a measurement or object beam (OB) having, ideally, equal optical path lengths. After reflecting from surfaces being measured OB is combined with RB and provided to sensors which measure the intensity associated with each of the wavelengths. Any difference between the intensities is indicative of a difference in the optical path lengths of OB and RB and is a function of the polarization state of each of the three returned wavelengths. Differences in optical path length may be indicative of a difference between a reference surface and a test surface, or a difference in thickness or index of refraction across an object. Two multi-mode laser diodes (12, 14) are provided for generating the three optical wavelengths.

Abstract: Optical metrology method and apparatus wherein three optical wavelengths are generated and separated into a reference beam (RB) and an object beam (OB) having substantially equal optical path lengths. After reflecting from a surface being measured OB is combined with RB and provided to sensors which measure the intensity associated with each of the wavelengths. Any difference between the intensities is indicative of a difference in the optical path lengths of OB and RB and is a function of the polarization state of each of the three returned wavelengths. Differences in optical path length are shown to be indicative of a displacement of the object being measured. Preferably, two multimode laser diodes (12,14) are provided for generating the three optical wavelengths. Two synthetic wavelengths are derived from the three optical wavelengths and are employed to improve the precision of measurement while retaining a large dynamic range made possible by the use of a large synthetic wavelength.

Abstract: A CW and/or pulse coherent radiation detection system (10) includes at least one radiation detector (14) having a plurality of discrete radiation detector elements (A-D) disposed upon a surface thereof. A coherence length discriminator (CLD), for example an etalon (12), is constructed so as to vary an optical path length therethrough at a plurality of locations. The CLD is disposed relative to the radiation detector such that radiation passing through the CLD is received by the discrete radiation detector elements. The apparatus further includes a drive (16) for translating the CLD relative to the radiation detector so as to modulate only coherent radiation passing through the CLD. The drive is preferably a reactionless drive having an energy consumption made small by the use of small CLD motions that correspond to the dimensions of individual detector elements. The coherent radiation detector is also shown to be usable for detecting an angle of arrival of coherent radiation.

Abstract: A system for fabricating optical elements includes a source of optical radiation that provides an optical beam, the system includes an intensity controller in the path of the beam. The intensity controlled beam is directed toward a substrate disposed on a stage. The stage is adopted to be controllably translated in accordance with an optical intensity map.

Abstract: A semiconductor laser pulse compression radar system utilizes a semiconductor laser source 16 for generating light for transmission towards a target 27. A modulator 15 pulses and modulates the light according to a preselected code, and a transmitter telescope 18 launches the light. Portions of the pulsed light reflected by the target 27 are gathered by a receiver telescope 28 and are converted to electrical current pulses by an avalanche photodiode 30. The pulses of electrical current are demodulated by demodulator 31, which includes a pulse compression filter 35 which has the conjugate time-frequency characteristic of the modulator. A display/counter 36 displays the range of the target from the system.

Abstract: A laser system for measuring dimensional aberrations across a target surface includes a laser diode for producing a diverging beam of laser emission. A mask spaced from the diode in the beam has an aperture therein and can be moved so as to translate the aperture to selected locations laterally with respect to the beam. The mask blocks emission from impinging on the target except for emission transitting the aperture. Emission reflected from a segment to the target returns through the aperture back into the laser diode. An AC current is added to the driver current to modulate the emission. A lock-in amplifier of a photodetector signal adds feedback current to the driver current to lock in phase angle, so that the feedback current is a measure of the aberrations.

Abstract: A charge-coupled imaging device (FIG. 3) is thinned to allow for backside illumination. The device is further enhanced using ion implantation techniques to establish an electrical field (44) at the back surface, which functions to drive free electrons to potential wells generated beneath a gate structure (40) on the front surface. The device structure allows for both front side and backside illumination and is useful as an imaging device in applications where it is necessary to combine images from two different optical sources. The imaging device is particularly useful in terrestrial guidance systems (FIG. 5) where the imaging device is used to detect guide stars from a large guide star field. In such systems, the imaging device must be translated within an X-Y plane in order to cover the entire guide star field. In order to accurately know the position of the imaging device, optical fiducial marks are imaged onto a side of the imaging device opposite the side receiving the guide star photons.

Abstract: The phase ambiguity of conventional interferometers may be removed by using two laser diodes of different optical frequency to generate a synthetic wavelength. However, the stability requirements for a two-color interferometric laser gauge that must provide unambiguous determination of the optical fringe order over a large distance can be severe. The invention determines upper limits on the optical wavelength uncertainity and expresses same as a function of optical path difference between object and reference beams, phase measurement errors and the synthetic wavelength. A wavelength stabilization arrangement involves simultaneous servo control of two laser diodes (10, 12) with a single Fabry-Perot etalon (36). An embodiment of the invention demonstrates its effectiveness for long-term stabilized two-color interferometry over a distance of 250 mm, with a 15 .mu.m synthetic wavelength and a repeatability of 40 nm. For periods of less than 1000 seconds, the repeatability is eight nm.

Abstract: A fiberoptic leader connected between a missile and a launch tube is paid out upon missile launch with a controlled degree of bend in the fiberoptic filament, and is furthermore protected from blast effects in the launch. The fiberoptic filament is stiffened within a leader comprised of a TEFLON sleeve insulating the fiberoptic filament. A protective sheathing of high tensile strength longitudinally wires are disposed about and encase the TEFLON sleeve, and in turn are encased within an outer sleeve. The stiffened leader is led along the longitudinal length of a C-shaped channel attached to the side of the missile. The channel is disposed upon a longitudinal portion of the missile. The stiffened leader is laid against and under one of the channel arms from the aft end of the missile, where the fiberoptic leader is fed out during launch, to a forward end of the missile and channel. The leader is then led across the width of the channel to the opposing arm of the C-shaped channel.

Abstract: A triangle wave generator (10) which is programmable, and which provides variable amplitude, frequency independent, triangle waves over a wide frequency bandwidth while employing a low voltage power source. The triangle wave generator (10) comprises a square wave input signal source (12) and a reference voltage signal source (14). A first amplifier (16) amplifies the square wave input signals and couples them by way of a transformer (34) to an integrator (36,40) which generates triangle wave output signals in response thereto. A second amplifier (18) connected to the triangle wave signal and to the transformer coupled square wave current source for the purpose of providing a bootstrap. A third amplifier (20) samples and compares the triangle wave output signals to the reference voltage signals and generates output error signals in response thereto.

Abstract: A staged missile which is reconfigured in-flight solely by changing vehicle dynamics enabling packaging of kinetric energy kill capability in severely constrained envelopes, thus retaining the use of existing tactical assets to counter advanced armored threats.

Abstract: Optical systems with very long eye relief and large working distances (10) and (110) with four lenses (12), (14), (16), (18) and (20) and three lenses (112), (114) and (116), respectively, have lens surfaces shaped to focus upon an object such that a high resolution image is formed at infinity substantially over the entire field of view. High resolution and low distortion are substantially maintained independent of the user's eye location.