A laser referencing system is disclosed which is used in a refractively scanning interferometer. The interferometer optics comprise a fixed wedge-shaped prism having a beamsplitter surface, a movable wedge-shaped prism, and two corner cube reflectors. A laser clocking beam enters the interferometer on a path below the infrared analytical beam, and leaves the interferometer on a path above the infrared beam. Quadrature control of the laser beams is used to control the ends of the scanning sweeps, eliminating the need for a third, "white light" interferometer beam. ZPD alignment is accomplished by horizontal adjustment of the fixed beamsplitter prism. The interferometer optics are supported three-dimensionally in a cast shell.

A Fourier transform interferometer for rapid scanning of scenes such as explosions wherein an incoming beam of light to be analyzed is split by a beam splitter into a first portion and a second portion. The first portion of the incoming light is sent down one arm of the interferometer where it passes through a rotating scanning cube for changing the path length in that arm of the interferometer. The light is then reflected by a retro mirror and sent back through the scanning cube to the beam splitter for sending a portion of the returning beam to a detector. The second portion of the incoming light is sent down a second arm of the interferometer where it passes through a compensator. The light is then reflected by a retro mirror and sent back through the compensator to the beam splitter for sending a portion of the returning beam to a detector. The first and second portions of the incoming light having differing path lengths interfere and the detector measures the fringes created.

A spectrometer system is disclosed in which the sample-containing chamber is a separately constructed, enclosed modular unit which is readily attachable to, and detachable from, one wall of a housing which constitutes the basic unit of the spectrometer, and which contains an interferometer, one or more detectors, and other portions of the system. Various examples of the essentially unlimited types of sampling modules are disclosed. Also, automatic sample loading and unloading devices are disclosed, which are feasible because of the modular construction. And means of loading and unloading samples without purge loss are disclosed, which are feasible because of the modular construction.

An interferometer/spectroradiometer that uses a beamsplitter means for dividing an input beam into two separate beams and presents the resultant beams to a rotary refractive window from symmetrically oriented optical elements such that the optical path differences through the refractive window as it rotates are additive and non-linearities are subtracted. The beams are returned through the refractive window to the beamsplitter for dividing the input beam, where fringes are generated for application to appropriate detectors. The detector output is applied to Fourier transform computer equipment for digitizing and processing for presentation on a spectrum display device.

A double beam interferometer using the refractive scanning method is disclosed which includes a first fixed optical body having a pair of parallel principal surfaces, a second fixed optical body having a pair principal surfaces, one of which faces and is parallel to one principal surface of the first fixed optical body, and the other of which makes a predetermined angle with the one principal surface of the second fixed optical body, a movable optical body having a pair of principal surfaces, one of which faces and is parallel to the other principal surface of the second fixed optical body, and the other of which makes the predetermined angle with the one principal surface of the movable optical body in such a manner that the predetermined angle of the second fixed optical body and the predetermined angle of the movable optical body are formed on opposite sides, driving means for moving the movable optical body on a plane containing the one principal surface of the movable optical body, a semitransparent mirror provided on one of facing principal surfaces of the first and second fixed optical bodies for dividing light from a light source into transmitted light and reflected light, and first and second reflecting mirrors for reflecting the transmitted light and reflected light in a direction opposite to an incident direction, respectively.