Optical measurement of absolute flatness with the deflectometric measurement systems at PTB

被引:10
作者
Ehret, Gerd [1 ]
Schulz, Michael [1 ]
Baier, Maik [1 ]
Fitzenreiter, Arne [1 ]
机构
[1] Phys Tech Bundesanstalt, D-38116 Braunschweig, Germany
来源
11TH INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (SRI 2012) | 2013年 / 425卷
关键词
D O I
10.1088/1742-6596/425/15/152016
中图分类号
TH7 [仪器、仪表];
学科分类号
0804 ; 080401 ; 081102 ;
摘要
Highly accurate flatness measurements are needed for synchrotron optics, optical flats, or optical mirrors. Recently, two new scanning deflectometric flatness measurement systems have been installed at the Physikalisch-Technische Bundesanstalt (PTB). The two systems (one system for horizontal and the other for vertical specimens) can measure specimens with sizes up to one metre with an expected uncertainty in the sub-nanometre range. In addition to the classical deflectometric procedure, also the 'extended shear angle difference (ESAD)' and the 'exact autocollimation deflectometric scanning (EADS)' procedures are implemented. The lateral resolution of scanning deflectometric techniques is limited by the aperture of the angle measurement system, usually an autocollimator with typical apertures of a few millimetres. With the EADS procedure, the specimen is scanned with an angular null instrument which has the potential to improve the lateral resolution down to the sub-millimetre region. A new concept and design of an appropriate angular null instrument are presented and discussed.
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页数:4
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