Measuring the optical beam profile is of critical importance in a number of laser applications. It is important to ensure that the beam of the right profile is generated during the design and fabrication phase of lasers. A beam profiler is an apparatus that captures, displays and records the intensity of the laser beam with reference to a plane that is transverse to the direction of beam propagation.
In certain optical systems, such as optical memory, the focusing light needs to be of the right shape and size in order to have the expected output. In laser systems that deal at the submicron level, the optical trapping needs to happen accurately. The beam profile characteristics that are measured by beam profilers are listed below:
- Beam width
- Beam quality (M2 value)
- Beam divergence
- Beam astigmatism
- Beam jitter
Beam Profiling Techniques
The common beam profiling techniques are classified as camera imaging techniques and photo detector techniques.
Photo Detector Technique
Knife edge and scanning slit profiling are the two photo detector techniques used for beam profiling. The knife edge technique chops the beam with a knife and measures the transmitted power. Scanning slit profilers make use of a narrow slit through which the beam is made to pass through.
Camera Imaging Technique
In this technique, a laser beam is attenuated and focused onto a CCD camera and its intensity is measured. Silicon CCDs are most commonly used for beam profile measurements.
Applications of Beam Profilers
Some of the common applications of laser beam profilers are:
- Making scientific measurements such as irradiance and Gaussian beam intensity
- Industrial applications that require accurately focused beams
- Medical applications that require highly focused laser beams.