Spatial laser beam profiling at focus is an essential part of quantitatively characterizing the shaped laser beam. We will
discuss new methods that can profile almost any laser at almost any power level.
Electronic laser beam profiling is now a widely accepted method to measure the mode quality and spatial profile of a
laser beam. For the most part, profiling has been limited to the unfocused or 'raw' beam, because the energy density or
irradiance in the vicinity of focus is high enough to destroy almost any measurement device. Recent developments in
measuring technology now enable users to make beam profiling measurements at and near the focus of many lasers. We
discuss two new designs and show examples of how they function.
Evaluating the success of beam shaping techniques requires the measurement of the resulting beam profile. Laser beam profilers have been used extensively throughout the laser industry to enable users to evaluate the "quality" of their laser beam. Profilers have made many strides in recent technology, including new cameras, new beam sampling optics, new calculation algorithms, and new profile displays. New cameras include high resolution, megapixel arrays, digital CCDs, FireWire cameras, and phosphor coated CCDs for extending near IR response. Improved beam sampling optics includes components for eliminating polarization effects and optics for sampling high power multi-kilowatt YAG and CO2 lasers. In recent years ISO has refined calculation definitions for measurement of beam width, divergence, flattop beams, and many others, thus standardizing laser profile characterization. Beam profile displays in both 2D and 3D have been improved to provide more intuitive insight.
For the past 28 years, the Laser Hardened Materials Evaluation Laboratory (LHMEL) at the Wright-Patterson Air Force Base, OH, has worked with CO2 lasers capable of producing continuous energy up to 150 kW. These lasers are used in a number of advanced materials processing applications that require accurate spatial energy measurements of the laser. Conventional non-electronic methods are not satisfactory for determining the spatial energy profile. This paper describes continuing efforts in qualifying the new method in which a continuous, real-time electronic spatial energy profile can be obtained for very high power, (VHP) CO2 lasers.
Direct spatial profiling of high power near IR lasers can be extremely useful in determining the applicability of these lasers in materials processing. Because of the construction of these lasers, direct imaging in real time has been nearly impossible due to the high energy density at the focus. It is not possible to image a raw beam, because there is no raw beam in the conventional sense. We discuss the construction of a new imaging target that allows direct spatial imaging at the focus of these lasers, and give examples of its applicability.
For the past 28 years, the Laser Hardened Materials Evaluation Laboratory (LHMEL) at the Wright-Patterson Air Force Base, OH, has worked with CO2 lasers capable of producing continuous energy up to 150 kW. These lasers are used in a number of advanced materials processing applications that require accurate spatial energy measurements of the laser. Conventional non-electronic methods are not satisfactory for determining the spatial energy profile. This paper describes a new method in which a continuous, real-time electronic spatial energy profile can be obtained for very high power, (VHP) CO2 lasers.
The increased use of high power Semiconductor lasers for industrial applications has created a demand for accurate, detailed beam profiling devices. Current technology, however, limits the use of conventional beam profiling instruments to about 1.5 kW. We will discuss a novel method of profiling high power YAG (1064 nm) industrial lasers up to 4kW in average power and 30 mm in raw beam diameter, using a camera-based, computer operated beam-profiling device. The new instrument is portable and employs conventional optics to attenuate and reduce the raw beam, and is designed to be used in an industrial environment.
Continuous monitoring of high power (above 2 kW) CO2 laser beams with camera based systems has not been effective because beam sampling optics have not been available. Camera based systems allow real-time imaging of the entire beam profile which in turn enables real-time tuning and alignment of the laser, as well as enabling instantaneous recognition of beam misalignment in the optical delivery train. Spiricon and II-VI have jointly developed a new method
for in-line, passive sampling and beam profiling of high power, multi-kilowatt CO2 lasers. The system uses conventional optics in a novel sampling arrangement, coupled to a Spiricon Pyroelectric IR Camera and Laser Beam Analysis
Industrial Lasers must have high reliability and repeatability so that the process for which they are to be used is profitable and successful. Current methodology for measuring the performance of high power industrial lasers is incapable of real time data. We describe two new instruments; a new on-line, in-line laser beam performance monitoring system that not only calculates M2 and divergence angle, but also provides real time beam profiling, and an at-line beam profiling system that can calculate beam widths and many other critical parameters in real time. The information obtained from these measurements allows the operator to monitor beam performance in real time, speed tuning and adjustment. more accurately predict maintenance intervals and aid in troubleshooting malfunctions. Actual examples of different lasers will show the value of these systems.