Design process for NIF laser alignment and beam diagnostics
In a controller for an adaptive optic system designed to correct phase aberrations in a high power laser, the wavefront sensor is a discrete Hartmann-Shack design. It uses an army of lenslets (like a fly` s eye) to focus the laser into 77 spots on a CCD camera. Average local tilt of the wavefront across each lenslet changes the position of its focal spot. The system requires 0.1 pixel accuracy in determining the focal spot location. We determine a small area around each spot` s previous location. Within this area, we calculate the centroid of the light intensity in x and y. This calculation fails if the spot regions overlap. Especially during initial acquisition of a highly distorted beam, distinguishing overlapping spots is difficult. However, low resolution analysis of the overlapping spots allows the system to estimate their positions. With this estimate, it can use the deformable mirror to correct the beam enough so we can detect the spots using conventional image processing.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 658937
- Report Number(s):
- UCRL-ID-129855; ON: DE98058852; BR: 39DP0200; CNN: W-7405-Eng-48
- Resource Relation:
- Other Information: PBD: 9 Jun 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Shack-Hartmann centroid detection method based on high dynamic range imaging and normalization techniques
Laser guide star experiment at Lawrence Livermore National Laboratory