Abstract: An optical focus sensing system is disclosed. The system provides a focus shift measurement capability utilizing the relative motion between two gratings to produce different diffraction orders which are separately detected by a pair of detectors to form signals having a phase difference proportional to the focus error corresponding to the planes occupied by the two gratings. A control circuit is responsive to the phase difference between the signals from the two detectors to provide a controllable focusing capability.

Abstract: Optical membranes having embossed data on their surfaces are made by dispensing the polymer/solvent mixture onto a rotatable supporting surface bearing the embossed data, spinning the rotatable surface under conditions sufficient to form the membrane from the polymer and removing the membrane, after formation, from the rotatable surface. Such membranes can be light-transmissive, light-reflective or, as desired, partially reflective and partially transmissive.

Abstract: A condenser useful in ring-field optics includes a device for homogenizing light with little or no change in light cone angle, or in the polar distribution of light linked to a device for channeling the light emerging from the homogenizing device equally, but with variable intensity, into an arc of light spots having a predetermined intensity, radius, width and direction, a device for magnifying the width of the arc of light spots, and for reducing proportionately its cone angle in the direction of its width while converting its shape from elliptical to circular with substantially symmetrical distribution of light, a device for transferring the circular arc of light spots to, and focusing the arc at an image plane while homogenizing the light along the length of the arc, and a device for easily changing arc radius. This condenser may include an autocollimator for aligning the condenser elements with one another, and with the projection optics of a photolithographic device.

Abstract: A method for measuring accurately the optical thickness and index of refraction of thin, optical membranes includes directing light onto the membrane at one or more known angles of incidence, finding at least one angle of incidence, called a null angle, where the membrane reflects substantially none of the incident light, then calculating the optical thickness of the membrane, its index of refraction, or both, from one or more such null angles. Apparatus for this purpose includes means for directing a light beam onto thin, optical membranes, means for varying the angle of incidence of a light beam upon the membrane, and means for detecting the angles of incidence of the light beam on the membrane, including the null angles.

Abstract: The apparatus forms one-to-one reticle images on a wafer. The apparatus includes means for holding a reticle containing an image pattern corresponding to the size of the desired wafer pattern. An illumination system substantially uniformly illuminates the reticle pattern. A one-to-one stationary projection optical system projects an image of the reticle pattern onto a predetermined focal plane. Suitable means such as a vacuum chuck holds the wafer. An alignment system steps and orients a wafer chuck to register markings on the individual dies of the wafer with the projected image of corresponding markings on the reticle. A fluid servo system acts on the chuck to hold at least a portion of the wafer in the predetermined focal plane of the projection optical system.

Abstract: The apparatus forms one-to-one reticle images on a wafer. The apparatus includes means for holding a reticle containing an image pattern corresponding to the size of the desired wafer pattern. An illumination system substantially uniformly illuminates the reticle pattern. A one-to-one stationary projection optical system projects an image of the reticle pattern onto a predetermined focal plane. Suitable means such as a vacuum chuck holds the wafer. An alignment system steps and orients a wafer chuck to register markings on the individual sides of the wafer with corresponding markings on the reticle. A fluid servo system acts on the chuck to hold at least a portion of the wafer in the predetermined focal plane of the projection optical system.

Abstract: A method and apparatus for receiving optical radiation representative of a scene and for generating a processed image having periodic spatial amplitude modulations; i.e., a sampled image which does not suffer substantial loss of overall illumination. In accordance with the invention there is provided a means for generating a plurality of ordered images of the scene, at least one of the ordered images being out of phase with respect to the other ordered images. Phase shift means are provided for imparting a phase shift to said at least one ordered image so that it is substantially in phase with respect to the other ordered images. Focusing means are provided for collecting the ordered images to obtain the processed image. In the preferred embodiment of the invention the plurality of ordered images are substantially non-overlapping. In this embodiment, the means for generating a plurality of ordered images includes a phase grating and a lens adjacent the phase grating.