A dual beam Fourier transform spectrometer produces two beams from a single infrared (IR) source. The beams are directed through a sample region, with one beam transiting a sample and the other beam transiting a reference cell. The sample and reference beams are then directed to a Michelson interferometer with cube corner retroflectors for optically cancelling the background signal from the separate sample and reference beams and for optically combining the sample and reference beams in an optic...

An interferometric device for measuring optical thin film parameters such as refractive index, thickness and absorption uses phase conjugate mirrors in place of standard mirrors. The optical thin film for which the refractive index, thickness and absorption are determined acts as a beam-splitter in the interferometer.

Optical interferometric sensors exhibiting enhanced measurand sensitivity and complete common-mode compensation. The sensors add two additional light couplers and two optical paths with predetermined path lengths to known optical sensors such as the Mach-Zehnder, Recirculating Delay Line, Michelson-Morley, and Fabry-Perot sensors to produce sensors which exhibit complete common-mode compensation thereby greatly improving measured signal-to-noise ratio. An electronic feedback circuit can be emplo...

Apparatus for automatic tracking and contour measurement comprising electro-optical sensing apparatus mounted on a CNC machining head for providing an output indication of contours of an object in the precise frame of reference of the CNC machining head.

In a laser interferometer for interferometric linear measurement, a semiconductor laser (1) energizes a measuring interferometer (7) with which there is coordinated a spatially directly adjacent reference interferometer (9). The output signal of the reference signal detector (22) of the reference interferometer (9) is used to effet in the event of changes in the refraction index of the medium occupying the reference section and the measuring section a frequency tuning of the semiconductor laser ...

A sawtooth voltage is applied to an integrated optic phase modulator by means of a high impedance variable current source in response to a charge rate control signal. The phase modulator's capacitance accumulates the charge which manifests a voltage comprising the sawtooth signal. The sawtooth signal is also provided to a comparator which in turn provides a discharge signal upon detecting the sawtooth voltage as being greater than a selected reference signal magnitude. The discharge signal is pr...

Interferometric scanning method(s) and apparatus for measuring test optics having aspherical surfaces including those with large departures from spherical. A reference wavefront is generated from a known origin along a scanning axis. A test optic is aligned on the scanning axis and selectively moved along it relative to the known origin so that the reference wavefront intersects the test optic at the apex of the aspherical surface and at one or more radial positions where the reference wavefront...

A method and an apparatus for measuring optical heterodyne interference in which a reference light and a measurement light differing in frequency is generated. The measurement light is S- or P-polarization light which is irradiated on a target through a polarization light beam splitter, and the reference light is P or S-polarization light which is reflected by a mirror. Interference of the measurement light from the target and the reference light reflected from the mirror is obtained by a light ...

The invention relates to a device for measuring a Doppler frequency shift, including an optical signal channel delivering a signal light beam illuminating a reference medium; and a reference channel delivering a reference light beam for detecting the Doppler frequency shift. The frequency shift is determined from the difference in frequency between the light signal illuminating the reference medium and the light beam returned by the reference medium. The device includes at least two light radiat...

A measuring apparatus provides data relating to the shape of an input radiation wavefront, the wavefront shape being describable at a pre-determined location in an optical system. The apparatus includes an aberration device which provides an aberration to the input radiation wavefront, the shape of which is defined by a filter function that is complex valued and has non-mixed symmetry, and a detector having a radiation sensitive surface capable of detecting the intensity of incident radiation on...