Computer generated holograms for the optical shop testing of aspheres

Schreiner, Roland; Herrmann, T; Roder, Janett; Müller-Pfeiffer, Stefan; Falkenstörfer, O.

doi:10.1117/12.612577

Cited by 12 publications

(5 citation statements)

References 2 publications

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“…This high degree of flexibility in generating complex wavefronts has made CGHs extremely useful. In the field of optical testing and metrology, CGHs are commonly used in optical interferometric system for measuring aspheric optics [1][2][3][4][5] . A reference asphere or a null lens is no longer needed with the help of CGH; the desired aspheric wavefront can be synthesized and stored in a CGH.…”

Section: Introductionmentioning

confidence: 99%

Design and location deviation of the computer generated holograms used for aspheric surface testing

2013

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Computer generated holograms (CGHs) are widely used in aspheric surface testing and metrology. The primary role of the CGHs is to generate any desired wavefronts to realize phase compensation. In order to eliminate alignment errors of CGH and the tested aspheric, this paper designs a new layout of CGH that has the advantages of high alignment accuracy and simple experimental operation. And further the influence of the location deviation of CGH and the tested aspheric mirror to the entire system is discussed; it shows that the error introduced by the CGH and the tested aspheric mirror tilting around the x-axis or y-axis as well as the tested aspheric mirror moving along the x-axis or y-axis direction is large.Then the CGH design principle and design process are reviewed. Finally, a CGH is designed for measurement of an aspheric mirror (diameter=226mm, F-number =2.2). Interferometric test results of an aspheric mirror show that the whole test system obtains the demanded high accuracy.

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Section: Introductionmentioning

confidence: 99%

Design and location deviation of the computer generated holograms used for aspheric surface testing

2013

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“…Although testing aspheric surface with CGH was proposed as early as in 1971 8 , it was not widely accepted until the repaid development of the semiconductor industry, which provided fabrication techniques for CGH. Nowadays, CGH with both high accuracy and high resolution can be fabricated with e-beam writing or laser direct writing 9, 10 , and it's on its way to becoming an established techniques for aspheric surface testing 11,12,13 . This paper describes our strategies of CGH design and fabrication for aspheric surface testing.…”

Section: Introductionmentioning

confidence: 99%

Design and fabrication of CGH for aspheric surface testing and its experimental comparison with null lens

Zhao

et al. 2010

SPIE Proceedings

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Computer-generated hologram (CGH) is an effective way to compensate wavefront in null test of aspheric surfaces and freeform surfaces. Our strategies of CGH design and fabrication for optical testing are presented, and an experiment demonstrating the compensation results of CGH and null lens is also reported. In order to design complex CGH, software was developed, with which we can design a CGH including three sections: main section for compensating wavefront in null test, alignment section for adjusting the relative position between CGH and interferometer, and fiducial section for projecting fiducial marks around the optics under test. The design result is represented in GDS II format file which could drive a laser-direct-writer-machine to fabricate a photomask. Then, a 1:1 replication process is applied to duplicate the patterns from photomask to a parallel optical substrate whose surface is error better than λ/60 rms. Finally, an off-axis aspheric surface was tested with CGH and null lens respectively. The test result with CGH (0.019λrms) is almost the same as the result with null lens (0.020λ rms). This experiment also demonstrated that fiducial marks projected by CGH can be used to guide the alignment of the optics and measurement of its off-axis distance.

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“…Any complex wavefront can be generated by CGH. The application of CGH in aspheric surface testing can achieve high detection accuracy without using expensive reference surfaces or null lenses [1][2][3][4][5] .…”

Section: Introductionmentioning

confidence: 99%

Design of twin computer-generated hologram for absolute testing of aspheric surfaces

2014

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Testing of aspheric surfaces by means of computer-generated holograms(CGHs)is well known. To perform an absolute test of rotationally symmetric aspheric surfaces, a specially designed computer-generated hologram (CGH) that reconstructs an aspherical wave as well as a spherical auxiliary wave. Since both phase functions have the same symmetry and their pattern is simultaneously encoded, we call this type of multiplex hologram a Twin-CGH. The spherical wave is used for calibration. The design principle of Twin-CGH is introduced in this paper. We mathematically analyze the Twin-CGH constructed by taking the phase corresponding to the linear combination of two weighted phase functions. We show that this Twin-CGH may be written as a new linear combination for the original phase functions with new weights. Then we absolutely test aspheric surfaces by Twin-CGH.

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Computer generated holograms for the optical shop testing of aspheres

Cited by 12 publications

References 2 publications

Design and location deviation of the computer generated holograms used for aspheric surface testing

Design and location deviation of the computer generated holograms used for aspheric surface testing

Design and fabrication of CGH for aspheric surface testing and its experimental comparison with null lens

Design of twin computer-generated hologram for absolute testing of aspheric surfaces

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