Abstract: Monochromatic exciting light is transmitted in a forward direction from a source through a sample to a spherical mirror. The spherical mirror reflects the light in a backward direction through the sample and images the light upon a flat mirror. The flat mirror reflects the light in the forward direction, through the sample, to the spherical mirror, thereby causing the light to be reflected in the backward direction, through the sample, to the source. The reflections increase the optical path length of the light through the sample, thereby enhancing a fluorescent emission therefrom.

Abstract: A first monochromator includes a diffraction grating that is adapted for occlusion by a mirror. When the mirror occludes the grating, a white light input is transmitted through the first monochromator and through a sample under test, thereby causing a transmission of non-absorbed light from the sample. When the grating is unoccluded, monochromatic light is transmitted from the first monochromator so that a selected bandwidth of fluorescence excitation energy is incident on the sample. Fluorescence emission from the sample is diffracted by a second monochromator which provides diffracted light which is recorded by a vidicon.

Abstract: Optical simulation apparatus using a video target image superimposed upon an appropriately blanked-out film transparency of background is used to train an observer in target tracking. The apparatus also includes means to occult all or a portion of the target image presented to the trainee by an appropriate foreground image.

Abstract: A member of a linear position measuring transducer is provided with a hole running parallel to its windings. In one embodiment, elements are inserted into the hole to expand or shorten the length of the transducer. In another embodiment, cutout slots are made between quadrature sections of windings and the elements are introduced into the hole to alter the relative spacing between these quadrature winding sections.

Abstract: Apparatus for correcting the error of a position measuring apparatus, the apparatus having a first measuring interferometer path of variable length and a second interferometer monitoring path of fixed length. Means are provided for monitoring the change in the optical path length of the monitoring interferometer due to environmental changes and for reflecting these changes in the indicated measurement of the measuring interferometer.

Abstract: Undesired images and reflections are eliminated in an in-line infinity display system by tilting the bi-refringent package of the display system at an angle with respect to a plane normal to the optical axis of the curved mirror in the display system and the observer's location so that the undesired images and reflections are directed outside the observer's field of view.

Abstract: A dual beam differential spectrophotometer using a rotating chopper wheel having reflective transparent, and opaque sectors transmits light alternately through standard and sample material cells for comparison. Diffuse reflectors insertable in the material cells permit the apparatus to be used either as a differential spectrofluorometer or as a differential absorption meter.

Abstract: A method for making an improved member of a position measuring transducer is disclosed, wherein the member has a pattern of uniformly pitched bars thereon. The method comprises the steps of superimposing a plurality of positionally shifted latent images of an initial pattern of bars having approximately uniform pitch upon a photo-sensitive material, and then processing the photo-sensitive material to produce a production pattern of bars having a significantly more uniform pitch than the initial pattern. The production pattern is used to produce an improved member of a position measuring transducer having a correspondingly greater accuracy than a transducer incorporating a member made directly from the initial pattern. A procedure for selection of the processing parameters to control the uniformity of spacing between bars and to adjust the width and relative position of the "gray" transition region at the bar edges is also taught. Finally, the production of improved scale members of INDUSTOSYN.RTM.

Abstract: Optical simulation apparatus in which three relatively movable images are input to the system. One of the images is produced by a physical display object and the other images are presented on display screens, superimposed by a beam-splitting mirror, and directed to an infinity display system. True apparent distances and relative parallax of the three images are simulated. The simulation is enhanced by tilting elements of the infinity display system and one of the display screens relative to the optical axis of the apparatus.

Abstract: A lens system for modifying the spherical aberration of optical apparatus comprises three groups of lens elements arrayed in order along an optical axis of the apparatus: a first lens group has a negative optical power; a second lens group has substantially zero optical power and is bent to have a substantial amount of spherical aberration; and a third lens group has a positive optical power. The relative spacing between the second lens group and the first and third lens groups is variable to modify the spherical aberration introduced into the optical apparatus.

Abstract: A position-measuring system in which an improved digital to analog converter accepts an error signal from a position measuring transducer, the error signal being processed to be a digital signal representation of the magnitude and two-state direction of a positional error. The system is constructed to operate as if the error signal input had three states, two directional states and an intermediate "dead zone.

Abstract: Two embodiments of an electronic measuring gage are disclosed, each suitable for the visual display of a workpiece dimension. A grinder gage of one embodiment has a single movable measuring probe with both coarse and fine travel components. The measuring probe is mounted on an inner coaxial shaft which is fitted within a sleeve-like outer coaxial shaft. The outer coaxial shaft is slidably mounted in the grinder gage housing for coarse travel and carries the inner shaft and measuring probe with it. The inner shaft is adapted for fine travel relative to the outer shaft, and resilient connection means are provided for connecting the two shafts. One element of an Inductosyn position-measuring transducer is fixed to the inner coaxial shaft and the other element is fixed to the grinder gage housing. A base probe and a positioning probe are also mounted in the housing to maintain the measuring probe and base probe colinear with a diameter of a round workpiece to be measured.

Abstract: Two relatively movable, spaced elements having electrostatically coupled sets of uniformly spaced interdigitated electrodes form a precision, high gain linear or angular position-measuring transducer. Coupling electrodes on one element capacitively couple to portions of the electrodes on the other element so that electrical connections to external excitation and detection circuitry need be made to only one of the two elements. The shape and dimensions of the electrodes can be arranged to reduce or eliminate undesired impedance variations, capacitive coupling and unwanted harmonic coupling wave frequency components.

Abstract: Apparatus for forming at or closer than infinity an image of a primary image source is disclosed. The apparatus employs a reflection-type holographic analog of a spherical mirror and a birefringent array of optical elements. The primary image source is linearly polarized and made incident upon the holographic mirror analog. The light from the primary image passing through the analog is given a circular polarization by a first quarter-wave plate, and a fraction of this light is reflected by a plane beam-splitting mirror back to the analog where it is collimated and transmitted again through the first quarter-wave plate, beam-splitting mirror, a second quarter wave plate and a second polarizer for viewing by an observer. The remaining fraction of circularly polarized light from the primary image passing through the first quarter-wave plate which is not reflected by the beam-splitting mirror passes through the second quarter-wave plate, which gives that light a linear polarization at a 90.degree.