Apparatus and method for laser beam diagnosis
An apparatus and method is disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA
- DOE Contract Number:
- W-7405-ENG-48
- Assignee:
- United States of America as represented by United States (Washington, DC)
- Patent Number(s):
- US 5042950
- OSTI ID:
- 867948
- Country of Publication:
- United States
- Language:
- English
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