Automatic YAG damage test benches: additional possibilities

Abstract

The automatic damage test benches allow to obtain more data in less time but also to imagine new laser damage tests. Thereby, new questions can be asked and more answers can be provided. In this paper, the 3 YAG automatic damage test facilities build up at the laboratory will be shown. There are based on well-known principles : an half wave plate to adjust the wished peak fluence and a scattered light measurement in real time to detect the damage appearances. Many tests are developed around these benches as the usual hon-i, N-on-i, R-on-1, S-on-i tests and raster scans previously proposed by other laboratories. On all our test benches, these standard tests are driven by the same software designed at the laboratory : "Wintfl". But new tests and characterizations are also added. Indeed, on these thcilities the aging ofthe optics at various repetition rate under constant fluence (like S-on-i with or without a limit number of shots) are carried out. An automatic defect count has been also implemented. This tool is able to evaluate the number of defects after cleaning or after coating but also between laser irradiation. New tests are also imagined. The so-called HR-on-i test (High Ramp), which is a R-on4 (Ramp) test without beginning at zero has been achieved. It allows to compare 1-on-I and R-on-1 distributions performed with exactly the same damage criterion. Other parameters can be investigated as the speed of the motor ramp during the R-on-1 test, the pulse repetition frequency during the S-on-i test,... In this article, after a short presentation of our test bench facilities, the convenient possibilities of automatic YAG test benches are illustrated with experimental results.

Design, optical characterization, and operation of large transmission gratings for the laser integration line and laser megajoule facilities

“…We measured laser-induced damage threshold at the wavelength of 1.064 m for the 1 grating and 0.355 m for the 3 grating by using an automated damage test facility that has been described previously. 15 Multiple pulses of increasing energy were sent on a site until scattering was detected by a diagnostic with a He-Ne laser source. A ramp-on-site (R͞1) procedure was employed.…”

<title>Automated set-up for extreme-ultraviolet mask lithography: the first step to count and clean in one</title>

“…They are equipped with YAG laser sources which can be tuned at 1064 nm or at one of the 3 harmonics (532 nm, 355nm or 266 nm) with pulse widths in the nanosecond regime (typically between 3 ns and 13 ns). These facilities were been built up to automatically determine what fluence withstands an optical component 3,4,5 . A diagnostic based on the detection of light scattering with a photomultiplier (PM) allows to determine on what laser pulse the optic is damaged (see PM in Fig.…”

NIF small optics laser damage test specifications

“…The advantages of this test method have been well documented in recent years (4)(5)(6) The technique is applied where comparison of manufacturing . processes or vendors is needed.…”