Spaceborne/airborne optics

Operating a laser system under high-vacuum conditions in space requires environmentally robust coatings and optics.

The key risk factors for failure are laser-induced contamination and coating degradation. You have to exclude increasing absorption, coating destruction or delamination due to cosmic, solar or laser radiation before sending out flight optics.1)

In various projects2) for DLR, ESA and NASA or their industry partners, LASEROPTIK has developed coatings and optics for laser applications in space or airborne environments and proven their functionality and durability.

MS and IBS coatings withstand extreme tem­perature ranges and working conditions requi­red for airborne laser optics. Additionally, we test the resistancy of specific coatings against gamma and neutron radiation for use in space. Environmental testing can be done by LASER­OPTIK or one of our partner institutes.

As part of the extensive qualification program, laser optics and coatings underwent several LIDT tests with simulated space conditions. DLR and LZH3) performed for example damage tests under vacuum conditions. See below for the results for an UV space laser HR 355 nm/s HT 532 nm/p + 1064 nm/s /45° with an AR on the rear surface, measured in vacuum:

Technical data:
LIDT with 10,000 on 1 LIDT,  vacuum 2 x 10-6 mbar, repetition rate 100 Hz.
Pulse duration: 3 ns (355 nm); 6.5 ns (532 nm);
12 ns (1064 nm).
Beam diameter: 160 µm (355 nm); 280 µm
(532 nm); 310 µm (1064 nm).

References and further reading:

1) Wernham, D. (2011): Optical coatings in space, in: Proc.  SPIE 8168, Advances in Optical Thin Films IV, 81680F (04. Oct. 2011).

2) Cosentino, A.; Selex Galileo S.p.A., Rome, Italy; D'Ottavi, A.; Sapia, A.; Suetta, E.: Spaceborne lasers development for ALADIN and ATLID instruments, Geoscience and Remote Sensing Symposium (IGARSS), 2012 IEEE International

3) Riede, W.; Allenspacher, P.; Lammers, M.; Wernham, D., Ciapponi, A.; Heese, C.; Jensen, L.; Maedebach, H.; Ristau, D. (2013): From ground to space: How to increase the confidence level in your flight optics, in: 45rd Annual Laser Damage Symposium on Optical Materials for High Power Lasers, 8885.  SPIE Laser Damage, 22.-25. Sep. 2013, Boulder, USA.

After a long search, coatings from LASEROPTIK proved to be optimal for meeting these extreme conditions and ensuring the continuous operation of Aeolus and Aladin.