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Factors to consider when choosing a laser beam profiling system

Beam Profiling: A Primer

By Allen M. Cary, Photon Inc.

Most people working with lasers today are trying to do something with the light beam, either as the raw beam or, more commonly, modified with optics. Whether it is printing a label on a part, welding a precision joint or repairing a retina, it is important to understand the nature of the laser beam and its performance. Laser beam profiling provides the tools to characterize the laser and know precisely what the beam is doing at the point of the work and if the optics are having the desired effect. Lasers and laser applications come in many varieties, varying in power density, wavelength, depth-of-focus, beam size, pulse duration and myriad other parameters. It is this variety that makes lasers so useful for interacting with and manipulating many different materials and media. But, it is also this variety that adds complexity to the beam profiling process.

Watch the video below on factors to consider when choosing a laser beam profiling system.

Beam Profiling Technology

Beam profilers come in many types, each with its own advantages and challenges. The basic types can be narrowed into a couple of categories—array-based or camera-based profilers and mechanical scanning apertures, knife edges and other devices. Today the camera-based and scanning aperture profilers are the leading techniques for most applications. Camera-based systems are generally silicon CCD or CMOS devices, although there are applications using arrays with pyroelectric detectors and microbolometers for detection of longer wavelength lasers. Scanning aperture systems combine a moving slit and single-element photo detector.

Other more specialized instruments, such as the Photon Goniometric Radiometer far field profiler use a scanning pinhole aperture to measure divergent sources in the far field.

Over the past few years the technology of camera arrays has improved dramatically with reduced pixel sizes, high dynamic range digital interfaces and electronic exposure and gain controls to vastly increase the usefulness of these devices as laser profilers. With the introduction of CMOS cameras, the costs have also come down significantly. Speed and jitter  control along with high dynamic range electronics have also improved the performance of the scanning aperture instruments, allowing them to achieve submicron precision for both pointing and beam size measurements. The availability of USB2 and Firewire (IEEE1394) interfaces for both these types of profilers has also increased their ease-of-use and convenience for connecting to both laptop and desktop computers.

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beam profiling

Internal working of a NanoScan scanhead