Cryogenic Etalon

Program Manager Scott Lindemann scottlindemann@michiganaerospace.com (734) 975-8777 x106

Program Description
Michigan Aerospace Corporation designed, fabricated and tested a spaceflight-qualified tunable Fabry-Perot etalon. This device is operated at 77 Kelvin from 7 - 11 microns. Tuning is accomplished via this use of ferroelectric single crystals and provides a range of travel of approximately 20 microns at operating temperature. Zinc Selenide was used for all transmitting elements. Titanium (Ti-6Al-5V Grade 5) was used for the etalon mount due to its low density, high strength, and coefficient of thermal expansion. The etalon was delivered to NASA’s Langley Reseach Center in July of 2004.”

Cryogenic Etalon Requirements and Parameters
Parameter	Desired	Minimum	Design Projected
Wavelength	9-12um	-	-
Gap	-	-	3.7mm
Finesse	20	12	19.3
Transmission	11%	8%	8.10%
Resolution	0.07 cm-1	6.32 Angstroms at 9.5um	6.32 Angstroms at 9.5um
Reflectivity	0.8	0.6-0.9	0.85
Dynamic Range	25um	5um (1/2 wavelength)	20.5
Free Spectral Range	Maximize	-	12.2nm

Thermal analysis picture of etalon during design

Two views of completed etalon