Shape measurements of mirror surfaces with a lateral-shearing interferometer during machine running

Discussions on on-machine measurement of aspheric lens-mold surface

“…The latter also developed a small OMM setup based on two zone plates, and its experiments proved that the method could realize the OMM of weak aspheric surfaces and its accuracy reached /5 in PV and /10 in RMS. Additionally, Nomura [23] invented a common path lateral-shearing interferometer for machine running combining with fringe-scanning method, which was little affected by mechanical vibrations and air turbulence. Fig.…”

“…That is to say, the onmachine measurement (OMM) of aspheric lens mold should be highly efficient, accurate and universal. Up to now, there are two major kinds of OMM methods: probe contacting method [3][4][5][6][7][8][9][10][11][12][14][15][16] and laser-based non-contacting method [13,[17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The contacting method uses the stylus or probe to scratch the surface of lens mold to achieve the section profile.…”

“…Therefore, the laser-based non-contacting OMM method is proposed to avoid the disadvantages of contacting method. References [18][19][20][21][22][23][24][25][26][27][28] have proposed some non-contacting OMM methods based the laser interferometry or laser holographic technology to realize the nondestructive testing. The other non-contacting OMM methods include the laser-triangle method [17], the laser-scanning method [2] and the fringe reflection (FR) method [29,30].…”

A cancellation technique for the validation of the reference profile of an interferometer

“…There are a number of methods for measuring the flatness profile using an interferometer, including the Michelson, Mach-Zehnder, Fizzo methods [1] and lateral shearing method [2]. These methods, except the lateral shearing interferometer, involving obtaining a fringe image that displays the surface profile by the interference between a reflected beam from a measured surface and a reflected beam from a reference surface.…”

An in-process measurement method for repair of defective microstructures by using a fast tool servo with a force sensor

“…The coordinate systems for the measurement and the repair cutting are also needed to have sub-micrometric correlations with each other so that the repair cutting can be made exactly against the micro-defect without influencing other parts of the mold surface. There are surface metrology-based methods existing for detection of the positions and profiles of defects on ultra-precision surfaces, such as the laser scattering method [22], interferometers [23], scanning probe microscopes (SPM) [24,25], confocal microscopes [26], contact thermal sensors [27] or optical sensors [28]. Some of them with special designs can be set up on an ultra-precision lathe for on-machine measurement.…”