scholarly journals Computational program to evaluate local defects type Chalmers Test on a reflective optical surface

2021 ◽  
pp. 18-24
Author(s):  
Benito CANALES-PACHECO ◽  
Esteban RUEDA-SORIANO ◽  
Luis Alberto RUIZ-AGUILAR ◽  
Raymundo Sergio NORIEGA-LOREDO
Keyword(s):  
Interference Pattern ◽  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Fizeau Interferometer ◽  
Optical Surface ◽  
Computational Tool ◽  
Optical Surfaces ◽  
Computational Program ◽  
Local Defects ◽  
Local Deformations

A computational tool is developed to measure the local deformations in optical surfaces from the interference patterns obtained by the Chalmers test principle and from the analysis of a reflective optical surface using a commercial Fizeau interferometer of the ZYGO. The tests were made on a concave spherical mirror with a radius of curvature of 60 cm and a diameter of 13 cm. To obtain the measurements of local deformations, a computational tool proposed for the localization of dark fringes is used by evaluating the maximum and minimum of the image obtained in the interference patterns. The results obtained show that the computational tool allows locating fringes within an interference pattern, allowing faster inter-fringe measurements and assigning an error on the surface in terms of wavelength.

Analysis of Interferometer with Micro-Mirror on Beam Splitting Cube

2021 ◽  
pp. 129-143
Author(s):  
L.N. Timashova ◽  
N.N. Kulakova
Keyword(s):  
Interference Pattern ◽  
Fourier Transforms ◽  
Design Parameters ◽  
Spherical Mirror ◽  
Topographic Map ◽  
Wave Surface ◽  
Beam Splitting ◽  
Concave Mirror ◽  
Part Surface ◽  
Wave Aberration

The control of the shape of the optical part surface by the interference method has become an integral part of the process of their shaping. With a precisely focused interferometer interferometry allows obtaining an interference pattern similar to a topographic map of the error profile of the wave surface under investigation. The interferometer must form a map of the optical surface with high accuracy --- the permissible distortion of the interference fringe caused by an interferometer error should not exceed 0.1 of the distortion value caused by an error on the examined surface. The dependence of the interference pattern formation on the errors in the arrangement of the interferometer components, i.e., defocusing, was theoretically analyzed using Fourier transforms. The analysis was performed for an interferometer containing a laser illuminator, a concave spherical mirror with a central hole, coaxial to the illuminator, and a beamsplitting element in the form of a cube-prism with a semitransparent hypotenuse face. On the first flat face of the cube-prism, a microspherical concave mirror is made with the center located on the optical axis of the interferometer. A method for calculating the defocusing of a controlled spherical mirror and the corresponding wave aberration of the working wavefront is presented. An example of calculating the design parameters of the interferometer and the permissible defocusing of the controlled spherical mirror is given

Form Accuracy of Optical Mould Inserts Made from Rapidly Solidified Aluminium Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 62-68
Author(s):  
Khaled Abou-El-Hossein
Keyword(s):  
High Precision ◽  
Surface Finish ◽  
Single Point ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Machining Parameters ◽  
Optical Surface ◽  
Form Accuracy ◽  
Optical Surfaces ◽  
Rapidly Solidified

Plastic optical components and lenses produced in mass quantities are usually manufactured using high-precision plastic injection technology. For that, high-precision plastic moulds with aluminium optical inserts made with extremely high dimension accuracy and high optical surface quality are used. Ultra-high precision single-point diamond turning have been successfully used in shaping optical mould inserts from various aluminium grades such as traditional 6061. However, extreme care should be taking when selecting machining parameters in order to produce optically valid surfaces before premature tool wear takes place especially when the machined optical materials has inadequate machining database. The current experimental study looks at the effect of cutting conditions on optical surfaces made from aluminium. The study embarks on helping establish some diamond machining database that helps engineers select the most favourable cutting parameters. The papers reports on the accuracy and surface finish quality received on an optical surface made on mould inserts from a newly developed aluminium alloy. Rapidly solidified aluminium (RSA) grades have been developed recently to address the various problems encountered when being cut by single-point diamond turning operation. The material is characterised by its extremely fine grained microstructure which helps extend the tool life and produce optical surfaces with nanometric surface finish. It is found the RSA grades can be successfully used to replace traditional optical aluminium grades when making optical surfaces. Surface finishes of as low as 10 nanometres and form accuracy of less than one micron can be achieved on RSA.

Simple yet accurate noncontact device for measuring the radius of curvature of a spherical mirror

2006 ◽  
Vol 45 (26) ◽  
pp. 6805 ◽  
Author(s):  
Maxim Spiridonov ◽  
David Toebaert
Keyword(s):  
Radius Of Curvature ◽  
Spherical Mirror

Characteristics of the defocused spherical Fabry-Pérot interferometer as a quasi-linear dispersion instrument for high resolution spectroscopy of pulsed laser sources

1968 ◽  
Vol 263 (1140) ◽  
pp. 209-223 ◽  
Keyword(s):  
Laser Beam ◽  
Optical Design ◽  
Pulsed Laser ◽  
Resolving Power ◽  
High Resolution Spectroscopy ◽  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Linear Dispersion ◽  
Fabry Perot ◽  
Very High

Defocused spherical mirror Fabry—Pérot etalons, in which the mirror separation is slightly less than the common radius of curvature, produce a multiple-beam fringe pattern of concentric rings, with quasi-linear spectral dispersion over an appreciable annular region corresponding to two free spectral ranges. The characteristics of these interferograms are discussed in relation to their many advantages for pulsed laser spectroscopy. These advantages include: (i) accuracy of frequency difference measurement; (ii) high illumination of the detector with moderate energy density in the laser beam; (iii) ease of alinement and permanent adjustment of the mirrors leading to the attainment in practice of a very high instrumental finesse (N R values of up to 90 have been achieved); (iv) measurement of degree of spatial coherence of laser beam; (v) ease of matching the interferogram to the spatial resolution of the detector. A simple optical path relation determines the positions of the fringes and the location of the quasilinear dispersion region. The interfering wavefronts, formed by multiple reflexion, have been numerically computed and summed to provide information on the finesse, fringe profiles, contrast and optimum conditions of use of this new, very high resolving power (107 to 108) quasi-linear spectrographic disperser. Constructional details are described and optical design criteria are discussed, together with the various experimental arrangements for employing the instrument. Comparison is made with the equivalent confocal and plane Fabry—Pérot etalons and methods of simultaneously measuring

scholarly journals Three-spherical-mirror test for radius of curvature measurement using a Fabry-Pérot cavity

2019 ◽  
Vol 27 (10) ◽  
pp. 13664
Author(s):  
Youichi Bitou ◽  
Osamu Sato ◽  
Souichi Telada
Keyword(s):  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Curvature Measurement ◽  
Fabry Perot
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