Fizeau interferometer

About: Fizeau interferometer is a research topic. Over the lifetime, 942 publications have been published within this topic receiving 8235 citations.

Measurement of transparent plates with wavelength-tuned phase-shifting interferometry

Abstract: A wavelength-tuned Fizeau interferometer is applied to the problem of flatness testing of transparent plates. When the plate is positioned at a specific distance from the reference surface and an integer-math 13-frame phase-shifting algorithm is applied, the system directly filters out unwanted interference arising from backsurface reflections. The resulting front-surface profile exhibits less than 2 nm of residual error attributable to spurious reflections from within the plate.

Fabry-Perot optical sensing device for measuring a physical parameter

Abstract: The optical sensing device and the method thereof are for measuring a physical parameter The device is to be connected to a light source which generates a multiple frequency light signal having predetermined spectral characteristics The device comprises a Fabry-Perot interferometer through which the light signal is passed, an optical focusing device for focusing at least a portion of the light signal outgoing from the Fabry-Perot interferometer, and a Fizeau interferometer through which the focused light signal is passed The Fabry-Perot interferometer includes two semi-reflecting mirrors substantially parallel to one another and spaced by a given distance so as to define a Fabry-Perot cavity having transmittance or reflectance properties which are affected by the physical parameter and which cause the spectral properties of the light signal to vary in response to the physical parameter The Fabry-Perot interferometer is provided with at least one multimode optical fiber for transmitting the light signal into the Fabry-Perot cavity and for collecting the portion of the light signal outgoing thereof The Fizeau interferometer includes an optical wedge forming a wedge-profiled Fizeau cavity from which exits a spatially-spread light signal indicative of the transmittance or reflectance properties of the Fabry-Perot interferometer The physical parameter can be determined by means of the spatially-spread light signal

White-light interferometric multimode fiber-optic strain sensor

Abstract: A white-light interferometric extrinsic Fabry-Perot strain sensor that uses a multimode fiber is demonstrated. The Fabry-Perot cavity length is measured with the help of a Fizeau interferometer. The sensor is described, and some results obtained at this time are given. The strain measurements are absolute and perfectly linear, with a sensitivity of 0.25 micrometers per meter (micro). the design of a thermally autocompensated strain sensor is also presented.

Method and system for profiling objects having multiple reflective surfaces using wavelength-tuning phase-shifting interferometry

Abstract: The invention features methods and systems for interferometrically profiling a measurement object having multiple reflective surfaces, e.g., to profile a selected one of the multiple reflective surfaces. The methods and systems involve: positioning the measurement object within an unequal path length interferometer (e.g., a Fizeau interferometer) employing a tunable coherent light source; recording an optical interference image for each of multiple wavelengths of the light source, each image including a superposition of multiple interference patterns produced by pairs of wavefronts reflected from the multiple surfaces of the measurement object and a reference surface; and extracting phases of a selected one of the interference patterns from the recorded images by using a phase-shifting algorithm that is more sensitive (e.g., at least ten times more sensitive) to a wavelength-dependent variation in the recorded images caused by the selected interference pattern than to wavelength-dependent variations in the recorded images caused by the other interference patterns.

An automated subaperture stitching interferometer workstation for spherical and aspherical surfaces

Abstract: Subaperture stitching is a well-known technique for extending the effective aperture and dynamic range of phase measuring interferometers. Several commercially available instruments can automatically stitch flat surfaces, but practical solutions for stitching spherical and aspherical surfaces are inherently more complex. We have developed an interferometer workstation that can perform high-accuracy automated subaperture stitching of spheres, flats, and mild aspheres up to 200 mm in diameter. The workstation combines a six-axis precision stage system, a commercial Fizeau interferometer of 4” or 6” aperture, and a specially developed software package that automates measurement design, subaperture data acquisition, and the mathematical reconstruction of a full-aperture phase map. The stitching algorithm incorporates a general constrained optimization framework for compensating for several types of errors introduced by the interferometer optics and stage mechanics. These include positioning errors, viewing system distortion, and the system reference wave. We present repeatability data, and compare stitched full-aperture measurements made with two different transmission spheres to a calibrated full-aperture measurement. We also demonstrate stitching’s ability to test larger aspheric departures on a 10 mm departure parabola, and compare the preliminary results with a full-aperture null test.