Noncollimated bidirectional shearing interferometer for measuring a long radius of curvature

A method for measuring a long radius of curvature with a modified half-aperture bidirectional shearing interferometer is described. A plane mirror of the interferometer is replaced with a test mirror, and the incident beam is decollimated by shifting of the source to equalize the widths of the bidirectional shearing fringes reflected from the plane and test mirrors. This method can be applied to concave and convex surfaces.     

Continuous wave terahertz spectrometer as a noncontact thickness measuring device

We present a low cost terahertz (THz) spectrometer with coherent detection based on two simple and robust dipole antennas driven by two laser diodes. The spectrometer covers frequencies up to 1 THz, with a peak signal-to-noise ratio exceeding 40 dB for a lock-in integration time of 30 ms. We demonstrate that the thickness profile of a sample can be reconstructed from an acquired THz image.     

An optical device for the measurement of the radius of curvature

Summary The present paper describes the construction and principle of a new and original optical instrument based on the optical section principle and designed for the control of objects whose surface radius of curvature is small.     

Accurate measurement of the radius of curvature of a concave mirror and the power dependence in a high-finesse Fabry-Perot interferometer

We describe the accurate measurement of the radius of curvature of a concave mirror in a Fabry-Perot interferometer with a finesse of 78,100. The radius of curvature of the concave mirror is determined by measuring the free spectral range and the transverse-mode range with the frequency response functions. The radii of curvature at two orthogonal (x and y) axes on the mirror surface resulting from the polishing nonisotropy were accurately measured to be r(x) = 1008.46 mm and r(y) = 1006.94 mm, respectively, with an accuracy of 8 × 10(-5). This accuracy is the best to our knowledge. The power dependence of the radii of curvature to the cavity internal intensity at a steady state was measured to be dr(x)/dI(c) = +60 μm/(MW/cm(2)) at the x axis and dr(y)/dI(c) = +47 μm/(MW/cm/(2)) at the y axis to an intensity of 2.1 MW/cm(2).     

An instrument for measuring the radius and profile of a rocking race

An algorithm is described for processing the results of two- coordinate measurements of a profile representing a partial circle. Information is presented on the instrument structure and on the functions executed by the microprocessor.Translated from Izmeritel'naya Tekhnika, No. 9, pp. 22–24, September, 1993.     

Errors in measuring the displacement of a Fabry-Perot interferometer mirror

Translated from Izmeritel'naya Tekhnika, No. 1, pp. 23–24, January, 1989.