Design and fabrication of a variable frequency grating and its application as a lateral-shear interferometer having a variable shear
✍ Scribed by R.P. Shukla; N.C. Das; Murty V. Mantravadi; D. Cook; M.D. Aggarwal
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 474 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0030-3992
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✦ Synopsis
The design and fabrication of holographic gratings of frequency variable from 50 to 750 lines/mm over length of 75 mm have been described. An application of these variable frequency gratings as a lateral-shear interferometer has also been suggested. The variable shear interferometer is found to be useful for testing of lenses with a maximum sensitivity in the detection of wavefront aberrations. Comparison of single-frequency grating having uniform pitch of 100 lines/mm with a grating of frequency variable from 59 to 220 lines/mm using an average pitch of 100 lines/mm over a small area as a lateral-shear interferometer have been made. Our experimental observations show that a small area of average pitch of 100 lines/mm on the grating having a variable frequency of 59-220 lines/mm over a distance of 75 mm behaves as a lateral-shear interferometer in the same way as any area of pitch of 100 lines/ mm on the grating of uniform pitch of 100 lines/mm.