Multiple-Selected-Line Unstable Resonator.
DEPARTMENT OF THE AIR FORCE WASHINGTON D C
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A new type of unstable resonator is provided which permits multiple-selected line operation. Selected line operation is obtained with a diffraction grating oriented at an angle different from the Littrow angle. Secondary feedback mirrors at the appropriate angles provide an independent three element cavity for each wavelength selected. Each three element cavity can be length tuned for line center operation for each selected wave length separately. The off-Littrow configuration is less efficient than a single line cavity at the Littrow angle since there are secondary zero order beams at each wavelength in addition to primary zero order beam at all selected wavelengths. The loss of power to the secondary zero order beams can be reduced, however, by using a grating of low efficiency which produces optimum output in the primary zero order beam for a high gain laser such as HF lasers.
- Lasers and Masers