Ultraviolet (UV) lasers are in many ways ideal industrial processing tools. They offer a noncontact method of producing fine microstructures on many substances, with minimal effect on surrounding material. The most important type of high power UV laser for industrial applications is the excimer laser. Available wavelengths include 351, 308, 248, 193, and 157 nm. The largest commercially available excimer lasers generate up to 200 W stabilized average power and up to 700 mJ pulse energy at 308 nm. Nd:yttrium aluminum garnet (YAG) lasers that utilize nonlinear crystals to transform the 1.06 μm output to its third (355 nm), fourth (266 nm), or fifth (213 nm) harmonic are also an important industrial UV source. More and more diode-pumped, frequency multiplied Nd:YAG lasers greatly impact the industrial processing market. The advantage of this laser is that it is physically compact, highly reliable, and mechanically rugged. Coupled with advantages of short wavelength output, recent improvements in laser reliability, cost of ownership, and performance are enabling UV lasers to be employed in an expanding range of applications. This article will briefly review those applications and their main laser requirements, and then present the most current advances in UV laser technology which address those needs.

A laser beam analysis system, with all passive optical components, has been developed that permits the real time measurement of a high power laser beam in the tens of kilowatts which can provide the laser's spatial profile, circularity, centroid, astigmatism and M-squared values using all the optics of a process application, including the focus lens and cover glass. At the heart of the technique is a Fabry-Perot resonator used with a focusing lens that provide a means to both attenuate and provide a multiplicity of focused laser spots each representing a spatial slice of the focused beam waist of interest onto a single CCD or CMOS camera. This arrangement provides real time data on the laser system's beam properties and is the basis upon which this work it done. The coatings of the Fabry-Perot resonator provide a high degree of attenuation of the input beam so that thermal lensing is not a factor in the measurement. By adjusting incident angle and spacing between the mirrors of the Fabry-Perot resonator, a large number of spatial cross sections can be seen on the detector. This permits then the possibility of evaluating any focusing objective whether long or short in focal length.

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A laser beam waist analyzer system has been developed that permits the real time focal spot measurement of a high power fiber laser in excess of ten of kilowatts and the ability to monitor thermal lensing of a laser and its optical system. The analyzer can provide a laser's spatial profile, circularity, centroid, astigmatism and M-squared values inclusive of the optics used in the process application. The system is very compact, measures in real time with no moving parts by incorporating an all passive optical design to obtain spot diameter, M-squared, Rayleigh length, beam waist position at power levels in excess of 20 kW in less than one second from laser off to laser on.

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