Temporal and Spatial Beam Diagnostics for High Power Lasers

A novel, non-intrusive technique is proposed for the temporal and spatial imaging of high-intensity infrared laser beams. The technique employs a visible probe laser to excite phosphorescence in a gas seeded into a flow of N2. The high intensity, IR laser beam passes through this gas jet flow. Irradiation of the emitting gas by the IR laser causes a reduction in emission proportional to the laser intensity. Cylindrical optics are employed to define an emitting sheet in a plane transverse to the IR laser beam. This emission is spatially resolved using a image-intensified TV camera synched to the probe laser to obtain the laser bem intensity profile. The temporal resolution of the device is defined by the emission lifetime of the gas of approximately 1 ms with a framing rate of 30 Hz. Commercially available image processing software may be employed to provide real-time diagnostic capability and images may be stored on standard video tape for post-processing. The proposed beam diagnostic technique is directly applicable to target plane beam diagnostics requirements at the High Engergy Laser Systems Test Facility (HELSTF) in the various test areas. It will provide the accuracy and teh reliablility needed to make high quality, rapid target plane beam diagnostics a reality.