The Sirah THU-205 (third harmonic unit) is designed to generate laser radiation in the UV wavelength range, from 197 to 212 nm, by third harmonic generation (THG). It is operated together with a Nd:YAG pumped dye laser, either a PrecisionScan or a Cobra-Stretch model.
The dye laser is operated in the red spectral range, from 591 to 636 nm. Its output beam is first frequency doubled by a temperature stabilized BBO crystal. Then, the resulting UV beam is sum frequency mixed with the residual dye laser beam in a second temperature stabilized BBO crystal. A set of 4 dichroic mirrors separates the generated UV beam from the two incoming. Due to the short wavelength, different dichroics sets are necessary to cover the entire wavelength range of the THU-205.
Additionally, the crystals may be used for one-step second harmonic generation (SHG).
|With DC-195 dichroics set||190 – 200 nm|
|With DC-205 dichroics set||200 – 210 nm|
|With DC-215 dichroics set||210 – 220 nm|
|1) single crystal operation, requires WS-Auto Pellin-Broca unit|
|Energy Output||1% of pump laser energy|
|Linewidth||approximately √3x dye laser linewidth / cm-1|
|Wavelength range with THG||197 – 220 nm|
|Wavelength range with SHG 1)||206 – 220 nm (THG-197 crystal, included)|
|215 – 280 nm (SHG-215 crystal, optional)|
|250 – 380 nm (SHG-250 crystal, included)|
|Maximum Pump Energy||650 mJ, with standard dye cell|
|800 mJ, with enhanced beam profile cell|
|1400 mJ, with 2nd main amplifier|
|Dye Laser Resonator||2400 lines / mm grating recommended|
|1800 lines / mm grating possible|
|Repetition Rate||10 Hz recommended|
|Crystal Tuning Mode||look-up table (Autotracking optional)|
|UV Beam Polarization||vertical, > 98 %|
|UV Beam Diameter (typical)||3 – 6 mm, depending on amplifier cell type|
|UV Beam Divergence||< 0.5 mrad|
All Dimensions in mm. Specifications are subject to change without notice.