Abstract: A plurality of gratings (G1, G2) are arranged together with a wavefront sensor, actuators, and feedback system to align the gratings in such a manner, that they operate like a single, large, monolithic grating. Sub-wavelength-scale movements in the mechanical mounting, due to environmental influences, are monitored by an interferometer (28), and compensated by precision actuators (16, 18, 20) that maintain the coherently additive mode. The actuators define the grating plane, and are positioned in response to the wavefronts from the gratings and a reference flat, thus producing the interferogram that contains the alignment information. Movement of the actuators is also in response to a diffraction-limited spot on the CCD (36) to which light diffracted from the gratings is focused. The actuator geometry is implemented to take advantage of the compensating nature of the degrees of freedom between gratings, reducing the number of necessary control variables.

Abstract: A rear projection screen for use with a projection lens which has an exit pupil (23) is provided. The screen has a light entering side and a light exiting side and comprises in order from said light entering side to said light exiting side: (a) a Fresnel structure (11); (b) a lenslet array (13); and (c) an opaque layer (15) comprising a plurality of pinholes, said pinholes being at locations which correspond to the images of the exit pupil formed by the combination of the Fresnel structure and the lenslet array.

Abstract: A plurality of gratings (G1, G2) are arranged to provide an aperture for incident light, which is diffracted by the gratings, which is larger than a single monolithic grating, and is operative to add coherently the energy from each grating so that it is operative in a coherently additive mode like a monolithic grating. Interacting movements in displacement and rotation are corrected by piston shifts of the gratings in the array in the direction perpendicular to the plane of the gratings. The shifts are implemented by displacing one grating with respect to another grating of the pair of gratings (G1, G2) in the array, or in the case of multiple gratings, other gratings in the array with respect to an aligned pair of array gratings.

Abstract: Microlens arrays, especially useful for optical coupling in optical switches of fiber optic telecommunications systems are produced with optical quality requisite for such applications with a replicating tool. This tool is made using a form tool set up in a rotating spindle of a precision air bearing milling machine at an angle of inclination such that the point of zero surface velocity is maintained outside of the surface of substrate machined to make the tool for replicating the arrays. The tip of the form tool has a profile corresponding to the profile of the lenses of the array, such as a generally circular profile having a radius centered at the axis of rotation of the form tool. The form tool is reciprocated with respect to the surface so as to form cavities of the desired profile, radius and depth which corresponds each identical lens of the array. To provide arrays the form tool is raised and the substrate is translated to preprogrammed positions.

Abstract: Microlens arrays, especially useful for optical coupling in optical switches of fiber optic telecommunications systems are produced with optical quality requisite for such applications with a replicating tool. This tool is made using a form tool set up in a rotating spindle of a precision air bearing milling machine at an angle of inclination such that the point of zero surface velocity is maintained outside of the surface of substrate machined to make the tool for replicating the arrays. The tip of the form tool has a profile corresponding to the profile of the lenses of the array, such as a generally circular profile having a radius centered at the axis of rotation of the form tool. The form tool is reciprocated with respect to the surface so as to form cavities of the desired profile, radius and depth which corresponds each identical lens of the array. To provide arrays the form tool is raised and the substrate is translated to preprogrammed positions.

Abstract: A system for projecting images is provided having a group of diffractive phase plates each encoded with different image information which have phase shifts aligned to reconstruct visible images in a Fraunhofer diffraction region. The plates are arranged along a path, and may represent successive frames of animation. A light source illuminates the plates and provides, when multiple plates are illuminated, a composite image representing image information encoded in such multiple plates. This composite image is a coincident superposition of reconstructed images from the multiple plates. A mechanism is provided for moving the plates along their path such that images projected from the system in the Fraunhofer diffraction region represent the composite image from successively different illuminated multiple plates or the reconstructed image from a single plate. Both monochromatic and multi-color channel phase plates may be used in the system.

Abstract: Apparatus for treating the surfaces of a plurality of wafers, such as semiconductor wafers, which comprises a container of treatment fluid having an open upper side for accepting a cassette containing a plurality of vertically disposed wafers. The cassette is supported in the fluid in said container and a transducer carrier is mounted in the lower portion of the container. The carrier has at least one megasonic transducer arranged to project a beam of ultrasonic energy upwardly over the vertical surfaces of the wafers. The transducer carrier is moved parallel with the wafer surfaces transversely of the container whereby the ultrasonic energy beam contacts and treats the entire surface of all of the wafers therein.

Abstract: A linear measurement interferometer 10 with a measurement axis directed toward a surface of a work piece 17 has a light source 11, a detection system 12, and a beam splitter 13 arranged to divide light from the source into test beams 21, 22, and 34 and reference beams 23, 24, and 33 that travel test and reference paths and recombine for detection by the detection system. Beam splitter 13 is arranged on the measurement axis with the work piece surface on one side of the beam splitter and the test beam path straddling the measurement axis on the opposite side of the beam splitter. A test beam retroreflector 25 mounted in the test path on the measurement axis reflects back the test beam from beam splitter 13 and is movable along the measurement axis without causing abbe error.

Abstract: A laser interferometer 10 uses light divided into reference beam 14 and test beam 15 traveling different paths from which beams 14 and 15 are reflected and recombined for detecting interference fringes. The path for test beam 15 is arranged to change in length with deviation transverse to its path. To do this, a reflective diffraction grating 25 is inclined relative to test beam 15 at the autocollimation angle of the grating to reflect the test beam back on itself from the inclined surface of the grating. Then transverse deviation of the region where test beam 15 is incident on grating 25 changes the path length of the test beam reflected from the inclined surface of the grating and allows a measurement.