Abstract: A method and apparatus are disclosed for correcting complex phase aberrations in a thick window in an airborne vehicle using the technique of phase conjunction. A conjugate element of the window is fabricated by machining. The conjugate element and an imaging lens are positioned behind the window such that the window is imaged onto the conjugate element. Phase aberrations produced when broadband radiation is passed through the window are removed when the wavefront passes through the imaging lens and conjugate element. In another embodiment, halogram is prepared of the wavefront passing through the window. The spatial phase information encoded in the hologram is read out by a phase measurement system and then fed into a computer where the conjugate wavefront is calculated. The conjugate wavefront is then written into a thin corrector plate of refractive material. The corrector plate with the conjugate wavefront imprinted thereon is then placed at the location where the hologram was initially formed.

Abstract: An optical filter for use with an imaging lens in an incoherent imaging system operating in broadband illumination for increasing the depth-of-focus of the lens while maintaining energy thru-put is disclosed. The optical filter comprises a transparent support having on one surface thereof an array of transparent, discrete steps of substantially equal size, each step having a thickness that differs from all other steps by at least the coherence length of the radiation to be passed and the size of the array being equal to the size of the lens. In use, the optical filter is positioned in front of the imaging lens. When so positioned, the depth of focus of the imaging lens is proportional to the size of the individual steps rather than the size of the lens while the energy thru-put of the imaging remains the same as it would be without the optical filter.

Abstract: An optical condensing device for use in combination with an optical imaging system to provide an image with improved contrast and resolution. The device uses a shaped fiber optic bundle coupled to a source of illumination to provide a plurality of coherent point sources, each of which is incoherent to each other, to illuminate the aperture of the optical system. The relative incoherence of each point source is achieved by varying the length of fibers in the shaped bundle so that no fiber is within the coherence length of any other fiber.

Abstract: An optical lithographic system for exposing small linewidths on integrated circuit substrates. The system comprises a deep ultraviolet (UV) source of illumination in conjunction with a dynamic coherent condenser system and an optical projection system and a deep UV sensitive photoresist.

Abstract: A three slit interferometric focus control device capable of focal positioning accuracies on the order of 300 angstroms. The device includes a zero path Michelson interferometer with reference and movable legs comprising, respectively, an annular reference mirror and the surface to be brought into position of best focus. A three slit plate positioned between the beamsplitter and energy detection device allows interference of light reflected off the movable and reference surfaces, creating an amplitude modulation signal. The energy detection device will measure a minimum energy intensity at the position of best focus.

Abstract: A system having a scaled anti-aliasing random phase filter for use in optical imaging systems having a sampled focal plane or an automatic focussing device. The filter is scaled so that it may be placed near the focal plane or automatic focus sensing device, yet produce the effect of an anti-aliasing filter at the exit pupil of the optical system. In one example, the filter includes a scaled hologram of a Sayanagi filter located at the exit pupil. In a second example, the filter includes a scaled double chirped diffraction grating.

Abstract: A high resolution optical lithographic system for exposing 0.25 microns to 0.5 microns linewidths on integrated circuit substrates. The system comprises a deep ultra-violet (UV) source of illumination in conjunction with an optical condenser system and high reduction ratio optical projection system and a deep UV sensitive photoresist. A three-slit interferometric sensor may be used to provide the resolution required to automatically focus the system.