High Efficiency Germanium Immersion Gratings
We have fabricated several germanium immersion gratings by single crystal, single point diamond flycutting on an ultra-precision lathe. Use of a dead sharp tool produces groove corners less than 0.1 micron in radius and consequently high diffraction efficiency. We measured first order efficiencies in immersion of over 80% at 10.6 micron wavelength. Wavefront error was low averaging 0.06 wave rms (at 633 nm) across the full aperture. The grating spectral response was free of ghosts down to our detection limit of 1 part in 10{sup 4}. Scatter should be low based upon the surface roughness. Measurement of the spectral line profile of a CO{sub 2} laser sets an upper bound on total integrated scatter of 0.5%.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 899391
- Report Number(s):
- UCRL-CONF-221103; TRN: US200708%%265
- Resource Relation:
- Journal Volume: 6273; Conference: Presented at: Opto-Mechanical Technologies for Astronomy, Orlando, FL, United States, May 24 - May 31, 2006
- Country of Publication:
- United States
- Language:
- English
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