Newport's UV broadband beam samplers are optimized to split off, or sample, a beam by Fresnel reflection. This optic is ideal for typical beam monitoring applications where minimum disturbance of the transmitted beam is necessary.
The precision optical substrate is uncoated on the front surface to achieve beam division by Fresnel reflection. The back surface is antireflection coated to prevent ghosting. A slight wedge in the substrate virtually eliminates internal fringes. Depending on the polarization of the incident beam, front surface reflectance from 1–10% can be attained at 45° incidence.
In a UV beam sampler, percentage of reflected light is determined by the Fresnel reflection from a single surface. At the nominal 45° AIO the beam sampler reflects approximately 10% and 1% for s- and p- polarizations, respectively. For measuring beam power, the beam sampler should be oriented such that the laser is p-polarized. This choice will maximize transmitted power and attenuate power incident on the detector.
UV Grade Fused Silica is synthetic amorphous silicon dioxide of extremely high purity providing maximum transmission from 195 to 2100 nm. This non-crystalline, colorless silica glass combines a very low thermal expansion coefficient with good optical qualities, and excellent transmittance in the ultraviolet region. Transmission and homogeneity exceed those of crystalline quartz without the problems of orientation and temperature instability inherent in the crystalline form. It will not fluoresce under UV light and is resistant to radiation. For high-energy applications, the extreme purity of fused silica eliminates microscopic defect sites that could lead to laser damage.