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

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.

Ion Beam Figuring System for Ultra-Precise Optics

2012 ◽  
Vol 516 ◽  
pp. 19-24 ◽  
Author(s):  
Zheng Yuan ◽  
Yi Fan Dai ◽  
Xu Hui Xie ◽  
Lin Zhou
Keyword(s):  
Ion Beam ◽  
Fused Silica ◽  
Ion Source ◽  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Gaussian Shape ◽  
Vacuum Chambers ◽  
Effective Aperture ◽  
Flat Mirror ◽  
Ion Beam Figuring

Ion beam figuring (IBF) is a novel technology for Ultra-precise optics. Material is removed from optic surface in atomic or molecular form by physical sputtering. Due to non-contact between the tool and the work piece, the problems involved in the conventional process are avoided, such as edge-effect and tool-wear. The ion beam figuring process is of high determinacy and high efficiency. All these properties make ion beam figuring one of the promising methods for producing mirrors of high precision with nm-rms accuracy. In this article, a new ion beam figuring system which contains doubled vacuum chambers is set up. Optics can be exchanged by a transport vehicle shuttling between the two vacuum chambers without opening the primary vacuum chamber and waiting for the ion source to cool completely, which means the efficiency can be increased greatly. A high performance processing robot contains three linear axes and two angular axes of motion, providing 5-axis ion source positioning capability with high accuracy. The angle can be up to 50° to figure very steep spherical and aspherical surfaces. Then, the beam removal function of Gaussian shape is obtained by an experimental method and it is extremely stable for a long time. Finally, two sample mirrors are figured by the ion beam figuring system: one is a fused silica flat mirror with a 100 mm diameter (90% effective aperture) and an ultra-precise flat mirror with a surface error of 0.89 nm rms, 14.7 nm PV is obtained; the other fused silica concave spherical mirror with a 100 mm aperture (90% effective aperture) and 420 mm radius of curvature is figured and a concave spherical mirror with 1 nm rms, 16.9 nm PV is obtained, which prove that the ion beam figuring system is favourable for the figuring process.

scholarly journals Изготовление и исследование свойств вогнутого кристаллического зеркала для проекта КОРТЕС

2019 ◽  
Vol 89 (11) ◽  
pp. 1770
Author(s):  
А.А. Ахсахалян ◽  
А.Д. Ахсахалян ◽  
C.А. Гарахин ◽  
Н.Ф. Ерхова ◽  
А.С. Кириченко ◽  
...  
Keyword(s):  
Radius Of Curvature ◽  
Maximum Deviation ◽  
Spherical Mirror ◽  
Crystalline Quartz ◽  
X Ray ◽  
Manufacturing Method ◽  
Spectral Selectivity ◽  
Diffraction Wave ◽  
Accuracy Of Measurements

The manufacturing method is described and the results of the study of the X-ray optical properties of a concave spherical mirror made of crystalline quartz are presented. The radius of curvature was 1630 mm. The shape of the mirror surface was studied on an interferometer with a diffraction wave of comparison. It was shown that in the whole processing area the maximum deviation from the nearest sphere was about 0.2 μm, and the square root of rms is 34 nm, which ensures high quality of images with an angular error of 2” (angular seconds). The reflection coefficients (about 7%) and the lower estimate of the spectral selectivity (λ / delta λ = 1775) are determined in the vicinity of the wavelength λ = 0.834 nm, which is close to the working wavelengths of the MgXII doublet (λ = 0.8418 and 0.8423 nm). During the bending of the crystal mirror, no change in the position of the Bragg peak and spectral selectivity was found within the limits of the accuracy of measurements.

scholarly journals Improving Thickness Uniformity of Mo/Si Multilayers on Curved Spherical Substrates by a Masking Technique

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 851 ◽  
Author(s):  
Zhe Zhang ◽  
Runze Qi ◽  
Yiyun Yao ◽  
Yingna Shi ◽  
Wenbin Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Magnetron Sputtering ◽  
Direct Current ◽  
The Other ◽  
Optical Systems ◽  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Dc Magnetron Sputtering ◽  
Thickness Uniformity ◽  
Planetary Rotation

In this work, a masking technique was used to improve the thickness uniformity of a Mo/Si multilayer deposited on a curved spherical mirror by direct current (DC) magnetron sputtering with planetary rotation stages. The clear aperture of the mirror was 125 mm with a radius of curvature equal to 143.82 mm. Two different shadow masks were prepared; one was flat and the other was oblique. When using the flat mask, the non-uniformity considerably increased owing to the relatively large gap between the mask and substrate. The deviation between the designed and measured layer thickness and non-uniformity gradually reduced with a smaller gap. The second mask was designed with an oblique profile. Using the oblique mask, the deviation from multilayer thickness uniformity was substantially reduced to a magnitude below 0.8% on the curved spherical substrate over the clear aperture of 125 mm. Multilayers still achieved a smooth growth when deposited with obliquely incident particles. The facile masking technique proposed in this study can be used for depositing uniform coatings on curved spherical substrates with large numerical apertures for high-resolution microscopes, telescopes, and other related optical systems.

A method for measuring the radius of curvature of a spherical mirror

1992 ◽  
Vol 27 (1) ◽  
pp. 24-27 ◽  
Author(s):  
J Engelen ◽  
S Y El-Zaiat ◽  
L Missotten
Keyword(s):  
Radius Of Curvature ◽  
Spherical Mirror

Development of a High-Speed Nanoprofiler Using Normal Vector Tracing

2012 ◽  
Vol 516 ◽  
pp. 606-611 ◽  
Author(s):  
Takao Kitayama ◽  
Daisuke Tonaru ◽  
Hiroki Matsumura ◽  
Junichi Uchikoshi ◽  
Yasuo Higashi ◽  
...  
Keyword(s):  
High Speed ◽  
Incident Light ◽  
High Spatial Frequency ◽  
Reconstruction Algorithm ◽  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Normal Vector ◽  
Light Path ◽  
Normal Vectors ◽  
Five Axis

A new high-speed nanoprofiler was developed in this study. This profiler measures normal vectors and their coordinates on the surface of a specimen. Each normal vector is determined by making the incident light path and the reflected light path coincident using five-axis simultaneously controlled stages. From the acquired normal vectors and their coordinates, the three-dimensional shape is calculated by a reconstruction algorithm. In this study, a concave spherical mirror with a 400 mm radius of curvature was measured. As a result, a peak of 30 nm PV was observed at the centre of the mirror. Measurement repeatability was 1 nm. In addition, cross-comparison with a Fizeau interferometer was implemented and the results were consistent within 10 nm. In particular, the high spatial frequency profile was highly consistent, and any differences were considered to be caused by systematic errors.

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