Abstract: A hulling optical bridge includes light means for supplying light and splitter means for splitting the light into a first light beam and a second light beam. The first light beam is directed to a surface having a parameter to be measured, and a first photodetector receives light reflected from or transmitted through the surface and generates a first signal indicative of the magnitude of the reflected or transmitted light. A second photodetector receives the second light beam and generates a second signal indicative of the magnitude of the second light beam. An electronic balancing circuit operates in a first mode when the parameter is maintained at a constant level, for adjusting the first and second signals to equal magnitudes, and operates in a second mode when the parameter varies, for applying a compensating signal to the first signal to balance the first and second signals.

Abstract: A high-speed three-dimensional surface measurement system for use in determining the surface of an object from at least one electronic signal produced by a mini-moire sensor. At least one light source illuminates at least a surface area of the object with at least one fringe pattern. The light source has a hidden change distribution grating or matrix of gratings for producing the fringe pattern. The grating has hidden variations distributed substantially across the grating. The grating has a pseudo-random grating pattern in which a nominal fringe pattern has a small uniform period with the hidden variations distributed statistically across the grating. The hidden variations are so small that at any one point on the grating a noise-like value of the hidden variations is on the order of an overall noise equivalent phase value. A CCD camera receives reflected illumination from the surface area and provides an electronic signal representative of reflected illumination received thereby.

Abstract: An apparatus for inspecting a phase shift mask includes a light source for irradiating a pattern of a phase shift mask including a light shield member and a phase member, a phase difference detector for generating from light transmitted through the phase shift mask a phase signal including the phase difference created by the phase member, a reference signal generator for generating a reference signal, and a calculation section for detecting a defect in the phase member of the phase shift mask by comparing the phase signal with the reference signal. The reference signal may be generated from a reference mask having the same pattern as that of the phase shift pattern or from CAD data for the formation of the pattern of the phase shift mask.

Abstract: An automatic lensmeter (48) for determining the refractive properties of a test lens (76) including optics (52, 58, 62, 64, 68, 70, 72, 74) for producing a collimated, nonrotational beam of light, equally disposed about and propagating along an optical axis (50), which is refracted by the test lens (76), a nonrotational mask (18) having an annulus (24) for generating a stationary elliptical loop (28) of light at a detecting plane (26), the loop (28) having a shape, size and location dependent on the refractive properties of the test lens (76), and a photodetector (31) at the plane (26) to intercept the loop 28. The lensmeter (48) has no moving optical components and, due to the loop 28, provides an infinite number of points to determine very accurately one or more of the refractive properties, thereby overcoming problems with prior automatic lensmeters having relatively rotational optics and/or providing a finite number of points at a detecting plane.

Abstract: An electro-optical modulator/antenna operates in the tunable diffraction ting mode to vary the magnitude of the zero diffraction order and consequently transmits optical information. A relatively thin slab of lithium niobate or equivalent electro-optic material has its lateral surfaces optically polished and its C-axis, or optical axis, running parallel to the polished lateral surfaces. At least one set of interdigital metallic electrodes are deposited on the face or just within the lateral surfaces to form, among other things, a diffraction grating that is orthogonally disposed with respect to the C-axis. When a potential source is coupled to the interdigital electrodes, the electric fields between adjacent electrodes change the crystal's index of refraction in accordance with the linear transverse Pockel's effect.