I-Tek, Inc.

United States of America as Represented by the Secretary of the Air Force

Mars, Incorporated

William B Wetherell

David A Womble

Edward P Wallner

A document validation subassembly is described. The subassembly includes a light mixer for generating at least one substantially homogenous light spot. The light mixer includes a light mixing chamber, at least one input port for accommodating at least one light source, at least one output, and at least one collimator connected to the output. In an implementation, the light mixing chamber is substantially spherical, but other shapes, such as cylindrical chambers, are also contemplated. Also described are solid core light mixer implementations.

Integrating light mixer

A method of mixing light from a signal source with light from a local oscillator for heterodyne or homodyne detection using differential detection techniques is described. In the method and apparatus of the invention, incoming light is matched to the polarization of the local oscillator no matter what the polarization of the incoming light is. A sequence of three polarization beamsplitters is utilized to achieve this match. The local oscillator signal and the incoming signal are incident on separate faces of a first polarization beamsplitter. Each is divided into two beams by that beamsplitter and paired with the orthogonally polarized component of the other, each signal/local oscillator pair exiting from one exit face of the first polarization beamsplitter. The second polarization beamsplitter resolves one of these pairs into sum and difference pairs of matched polarization which interfere and are detected by square law detectors, forming currents which are subtracted in a differential amplifier. The third polarization beamsplitter repeats this process with the other pair of beams from the first polarization beamsplitter. The result is two net output currents which between them contain all the phase and amplitude information needed to define and control the polarization of the incoming signal. In addition to reducing sensitivity to the polarization state of the incoming signal, the use of polarization beamsplitters substantially improves optical efficiency, in comparison to prior art using amplitude beamsplitters.

Polarization matching mixer

An atmospheric dispersion corrector having a housing capable of mounting therein either a pair of single prisms or a pair of compound prisms which can be either rotated with respect to each other or rotated, as a unit, simultaneously with each other. The specific requirements for the prisms making up both the pair of single prisms or the pair of compound prisms permit the corrector to rotate the single prisms or compound prisms through a particular rotation angle with respect to a vertical plane at which atmospheric dispersion correction over a broad spectral bandpass range can be achieved. These specific requirements encompass not only particular prism angles but also specific glass types from which the prisms are manufactured.

Atmospheric dispersion corrector

A compact, all-reflecting optical system for viewing distant objects. The system comprises a negative convex secondary mirror placed between a positive concave primary mirror and a positive concave tertiary mirror. The system has an eccentric field of view in that the field of view lies entirely on one side of the optical axis, and because of this, the light travelling from the object to the image will pass entirely outside the secondary mirror, both when entering the system and when travelling from the tertiary mirror to the image. Accordingly, with the present invention, there is no central obstruction and no consequent restriction on field of view and power distribution between mirrors as is found in prior art all-reflecting systems.

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Stoneham, MA, United States of America

William B Wetherell