Progress on GIMM Fabrication & Testing. M. S. Tillack, J. Pulsifer, K. Sequoia. High Average Power Laser Program Project Meeting University of Wisconsin – Madison 24–25 September 2003. Background (1): GIMM design concept.
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M. S. Tillack, J. Pulsifer, K. Sequoia
High Average Power Laser Program
University of Wisconsin – Madison
24–25 September 2003
The reference mirror concept consists of stiff, light-weight, radiation-resistant substrates with a thin metallic coating optimized for high reflectivity (Al for UV, S-pol, shallow q)
• Shallow angle stability• Damage resistance/lifetimeGoal = 5 J/cm2, 108 shots• Fabrication & optical quality• Contamination resistance• Radiation resistance
mirror #41, s/n 10157-024
50 nm sputter+1 mm e-beam
500 shots at 5 J/cm2
mirror #38, s/n 10157-021
100 nm sputter+2.0 mm e-beam
5.0 J/cm2 for 1000 shots
• Brightfield beam profiling• Darkfield beam profiling• Surface imaging
• Thin films on superpolished substrates – CVD SiC, 2-3Å roughness, 2-3 nm flatness over 3 cm – magnetron sputtering up to 250 nm – e-beam evaporation up to 2 mm• Solid polycrystalline metal – polished – diamond-turned• Electroplated and turned Al
Thin films are delicate, and damage easily and catastrophically
250 nm e-beam23,000 shots @4 J/cm2
1.5 mm e-beam86,000 shots @4 J/cm2
Nevertheless, we are continuing to explore methods to improve the coating quality and survivability
polished sample for comparison
drawing courtesy of J. Sethian, NRL
LONG PULSE AMPLIFIER
(~ 100's nsec)
( 20 nsec)
Only three pulses shown for clarity
1’ x 2’
For Reference: weak grainsNASA Technology Goals for JWST
James Webb Space Telescope (formerly known as NGST)
Deployment in 2011
7-m diam. lightweight optic
$825M project budget
Goal mirror cost of $300k/m2
Different candidates considered (Be is prime candidate)
Based on a 1996 Optical Telescope Assembly study, the following requirements were placed on JWST's optics:
The mirror should be sensitive to 1-5 microns (0.6-30 extended).
It should be diffraction limited to 2 microns.
It will have to operate at 30-60 K.
It should have an areal density of less than 15 kg/m2.
Schafer Corp. www.schafercorp.com
Rohm and Haas www.cvdmaterials.com
Sigma Technologies www.sigmalabs.com
MER corporation www.mercorp.com
Surface Optics www.surfaceoptics.com
Fabrication and handling protocols are under development: