CMM is used for measuring parts, optics, and for alignment of optical assemblies
Measuring Volume (700w x 1000d x 660h mm)
Accuracy, maximum permissible error (MPE) for measurement of length L: MPE = 1.5 + L/333 microns
e.g., for L = 1000 mm, MPE = 4.5 microns
Measuring range: 3-meter spherical volume
Point repeatability: 30 microns
Volumetric accuracy: 44 microns
Usage: Measure larger optical/mechanical systems and parts which do not fit in CMM or must be measured in-situ
Used for measuring very large parts and optical alignments of complex systems (e.g. GMT Wide Field Phase Testbed (WFPT), GMT G-CLEF spectrograph)
Accuracy = +/- (15 um + 6um x L m)
where L = measurement distance
e.g. for L = 2 m, Accuracy = 15 + 12 = 27 um
CE has several alignment telescopes used for optical alignments, e.g. Brunson, K & E
Used for measurement of angles, typically of use in optical alignments e.g. AIA, IRIS, Hi-C
Used to dynamically measure mirror LOS angles, e.g. piston tip/til assembly, steering mirror control accuracy, pickoff mirror tip/tilt accuracy on (e.g.) WFTP, AGWS and G-CLEF projects
Sub arcsecond accuracy
General purpose with 6-inch aperture, but set up on 5 axis stage for telescope alignments
Measure surface errors on flats, convex and concave spheres, aspheres
Measure transmitted wavefront errors on refractive elements and systems
Six-inch apertures using transmission flats and spheres
Measure surface errors on flats, convex and concave spheres, aspheres
Measure transmitted wavefront errors on refractive elements and systems
Accuracy governed by transmission elements; λ/20 for flats, λ/10 to λ/40 for spheres
For optical system alignments using diverger lenses
Measure system wavefront errors in double pass
Measure surface errors of concave parts
Accuracy gated by diverger lens, typically λ/8 PV