Milestone Report for High NA Optics Development International Sematech Project L1TH 112 Milestone4a: Specification Package for the Polished Mirror Substrate M1
The key task in initiating the fabrication of mirror substrates for the new High NA Camera is in preparing the specification package that details the substrate geometry and the specifications for the optical surface. This specification package has been completed for substrate M1, and the vendor has begun optical fabrication. In addition, mounting hardware has been designed and fabricated, and substrates have been bonded to the kinematic mounts. The design of the secondary substrate, M2, is underway, but will depend upon details of the PO Box actuation system and space constraints. Sufficient details of the M2 design to enable the vendor to procure material will be determined during October, while the final details of the mounting surfaces will be completed prior to the end of Q4 1999. The geometry of the Ml substrate is compatible with our planned approach for fixturing the optic within the PO Box and within metrology tools. The completion of this specification package required detailed consideration of: the mounting approach within the PO Box, degrees of actuation required for PO Box alignment, space constraints imposed by the vendor's metrology, requirements for LLNL metrology, and datum definitions needed for mechanical assembly of the PO Box. In addition, each of the degrees of freedom of the substrate has been properly constrained, and shown to be sufficiently insensitive to disturbance forces for minimizing deformation. An approach to fixturing has been adopted that extends beyond the approach taken for the Engineering Test Stand (ETS). For the ETS, each substrate, including spares, has dedicated mounting hardware that is used exclusively for each element. In exchange for a reduced risk of mounting-induced deformation, this incurred substantial expense and precluded optics from using interchangeable tooling. For the current High NA camera, we have adopted an approach that employs interchangeable mounting hardware that can be used for any of the substrates. This approach better accommodates a large number of manufacturing spares and the need for different mounting hardware for the PO Box and the metrology tools. This approach was enabled by designing the mounting hardware to minimize differences in the disturbance forces offered by different fixtures on the optic. An error budget and sensitivity analysis indicates that figure errors induced on the optics due to changes in fixturing are within the required tolerances for high quality imaging. The specifications for the optical surface on Ml are nominally the same as for the ETS substrates. These impose requirements for 0.25 nm rms for figure, 0.20 nm rms for mid-spatial frequency roughness, and 0.10 nm rms for high spatial frequency roughness. These designations are sufficient for controlling wavefront quality, image contrast, and multilayer reflectivity.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Defense Programs (DP) (US)
- DOE Contract Number:
- W-7405-Eng-48
- OSTI ID:
- 793707
- Report Number(s):
- UCRL-ID-136162; TRN: US0204468
- Resource Relation:
- Other Information: PBD: 8 Oct 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Quarterly Report for High NA Optics Development: Q4-1999 International Sematech Project LITH 112
Solar concentrator advanced development program. Final report