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Proceedings Paper

Point diffraction interferometry based on the use of two pinholes
Author(s): Nikolay B. Voznesenskiy; Dongmei Ma; Chunshui Jin; Haitao Zhang; Jie Yu; Mariia Voznesenskaia; Tatiana Voznesenskaia; Wenlong Zhang
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Paper Abstract

Point diffraction interferometer (PDI) has become the high degree of accuracy device. In the optical wavefront testing the measurement accuracy is much higher than 1.0 nm RMS. In the paper there is presented a new version of PDI with two independently controlled beams using a pinhole plate with two pinholes as a beam coupler instead of a single-mode fiber or single-pinhole plate. Theoretical analysis of the pinhole diffraction wavefront and double pinholes diffraction interference is given. The PDI is used to investigate an interferometer reference lens and compare measurement results. The device can test high NA, the interference is obtained in circularly polarized light, and fringe contrast is adjustable to measure surfaces with different reflectance. The measurement repeatability now has been sub-nm RMS (measured NA = 0.33). The experiment result provides guarantee for the measurement in the high degree of accuracy. In the double pinholes PDI, generating two ideal spherical waves through two pinholes, one wave is as the reference wavefront for interference test, another ideal wavefront is reflected to the pinhole plate by the test mirror, and the tested wavefront and reference wavefront bring interference. Advantages of such arrangement of the PDI are: high maximum numerical aperture (NA = 0.55), distinct fringe patterns of high contrast, high accuracy of surface figure testing and wave-front repeatability RMS error 0.3 nm.

Paper Details

Date Published: 22 June 2015
PDF: 9 pages
Proc. SPIE 9525, Optical Measurement Systems for Industrial Inspection IX, 95251K (22 June 2015); doi: 10.1117/12.2184771
Show Author Affiliations
Nikolay B. Voznesenskiy, VTT-NTM OÜ (Estonia)
Dongmei Ma, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Chunshui Jin, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Haitao Zhang, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Jie Yu, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Mariia Voznesenskaia, VTT-NTM OÜ (Estonia)
Tatiana Voznesenskaia, VTT-NTM OÜ (Estonia)
Wenlong Zhang, Changchun Institute of Optics, Fine Mechanics and Physics (China)


Published in SPIE Proceedings Vol. 9525:
Optical Measurement Systems for Industrial Inspection IX
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves, Editor(s)

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