CYLINDER LENS ALIGNMENT IN THE LTP
The Long Trace Profiler (LTP), is well-suited for the measurement of the axial figure of cylindrical mirrors that usually have a long radius of curvature in the axial direction but have a short radius of curvature in the sagittal direction. The sagittal curvature causes the probe beam to diverge in the transverse direction without coming to a focus on the detector, resulting in a very weak signal. It is useful to place a cylinder lens into the optical system above the mirror under test to refocus the sagittal divergence and increase the signal level. A positive cylinder lens can be placed at two positions above the surface: the Cat's Eye reflection position and the Wavefront-Matching position. The Cat's Eye position, is very tolerant to mirror misalignment, which is not good if absolute axial radius of curvature is to be measured. Lateral positioning and rotational misalignments of lens and the mirror combine to produce unusual profile results. This paper looks at various alignment issues with measurements and by raytrace simulations to determine the best strategy to minimize radius of curvature errors in the measurement of cylindrical aspheres.
- Research Organization:
- BROOKHAVEN NATIONAL LABORATORY (US)
- Sponsoring Organization:
- DOE/SC (US)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 15016724
- Report Number(s):
- BNL-74722-2005-CP; R&D Project: IO-04; KC-02-04-011; TRN: US200515%%865
- Resource Relation:
- Conference: SPIE CONFERENCE ON OPTICS AND PHOTONICS, SAN DIEGO, CA (US), 08/02/2005; Other Information: PBD: 26 Jul 2005
- Country of Publication:
- United States
- Language:
- English
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