Study of relation between crystal structure and laser damage of calcium fluoride

Minako Azumi; Eiichiro Nakahata

doi:10.1117/12.869770

3 December 2010 Study of relation between crystal structure and laser damage of calcium flouride

Minako Azumi, Eiichiro Nakahata

Proceedings Volume 7842, Laser-Induced Damage in Optical Materials: 2010; 78421U (2010) https://doi.org/10.1117/12.869770
Event: Laser Damage Symposium XLII: Annual Symposium on Optical Materials for High Power Lasers, 2010, Boulder, Colorado, United States

Abstract

The artificially grown calcium fluoride is one of key materials for microlithography and used for excimer laser optics etc. Such calcium fluoride is required high laser durability and laser induced bulk damage threshold (LIDT). However, the artificially grown calcium fluoride is not a complete crystal, and there are a lot of sub-grain boundaries inside the crystal that have the possibility of causing degradation of laser durability and LIDT. Moreover, mechanical properties of calcium fluoride are different according to the crystal axis, therefore there is a possibility that mechanical properties influences LIDT. In this study, we examined the relation between crystal structure and LIDT. First, we examined the relation between the crystal axis and LITD of single crystal calcium fruoride. The relation between the crystallographic axis and LIDT that the laser enters was examined. The ArF excimer laser and the fifth high harmonic of the Nd:YAG laser at 213nm were used for the irradiation source of light. We prepared samples that optical axes were <111>, <110> and <001> from the same crystal. From the result of this examination, when the laser irradiated in <111> axis, LIDT was the highest. Next, we observed the damage with polarizing microscope and optical microscope. The result of this observation suggested that the laser damage of calcium fluoride was related to the crystal orientation. Finally, we investigated the damage mechanism of calcium fluoride. It is thought that the laser irradiation induced stress is relaxed most easily when the optical axis is <111>. Therefore, LIDT of calcium fluoride is supposed to be highest when the optical axis is <111>.

Citation Download Citation

Minako Azumi and Eiichiro Nakahata "Study of relation between crystal structure and laser damage of calcium flouride", Proc. SPIE 7842, Laser-Induced Damage in Optical Materials: 2010, 78421U (3 December 2010); https://doi.org/10.1117/12.869770

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available