Industrial-grade nanosecond UV mirrors

Altechna’s industrial-grade UV mirrors (HR: Rs>99.9%, Rp>99.7% at 355 nm and AOI=45°) for nanosecond regimes offer the best quality-to-price ratio in the market. These mirrors are customer favorites, providing LIDT of 3.38 J/cm2 and 4.97 J/cm2 for p and s polarizations respectively (at 355 nm, 5.5 ns pulse duration (FWHM) and AOI=45°), which is more than enough for most applications. 

Next-generation optics for nanosecond pulses

Our next-generation nanosecond UV optical elements (HR: Rs>99.9%, Rp>99.7% at 355 nm, AOI=45°) boast absorption levels more than two times lower than standard UV mirrors, with reduced absorption crucial for limiting the impact of fatigue and avoiding heat accumulation.

Measurements carried out with laser irradiation at 355 nm and a power of 100 mW, with a 50 kHz repetition rate at a 45-degree angle of incidence indicate a decrease in absorption for s polarization from 210 ppm to 70 ppm, and for p polarization from 425 ppm to 170 ppm compared with standard industrial-grade UV mirrors. 

Next-generation optics for ultrashort pulses

Factors that cause absorption and laser damage are different for nano-second and ultrashort pulses (picosecond, femtosecond, and shorter pulses), so a different approach is required for manufacturing low-loss UV mirrors to work under this pulse regime.

To ensure that these upgrades contribute to an increase in the expected lifetime of optical elements operating under ultrashort pulses, LIDT measurements (343 nm, 1 ps (FWHM), AOI=45°) were carried out using different numbers of incident pulses. As can be seen in Figure 6, damage thresholds relating to HR (Rsp>99.5% @ 343 nm, AOI=45°) coatings for p polarization begin to drop when the number of pulses increases but then stabilize at 10 million pulses with an energy density of 0.719 J/cm2.

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