Pixel-based absolute test of a 1-m lightweight mirror for a space telescope

Large mirrors for spaceborne instruments require high-accuracy interferometry to measure their surface shapes. The mirrors often should be tested and fabricated more accurately than the reference optics against which they are compared. Furthermore, the mirrors require precise measurement to nanometer accuracy in weightless conditions. In order to address these requirements, an absolute test scheme should be adopted to separate the surface shape of the target mirror from the errors in the interferometer and the errors due to the gravity effect. In this manuscript, we propose a new pixel-based absolute test method that can extract the surface shape of the mirror without the errors caused by both the interferometer and the gravity effect. The proposed method is demonstrated with actual data from a lightweight primary mirror with a diameter of 1 m that has partially closed pockets at the back side and three bosses at the rim for flexure mounting.

[1]  Yun-Woo Lee,et al.  Optomechanical analysis of a 1-m light-weight mirror system , 2013 .

[2]  R E Parks,et al.  Pixel-based absolute topography test for three flats. , 1998, Applied optics.

[3]  K L Shu.  Ray-trace analysis and data reduction methods for the Ritchey-Common test. , 1983, Applied optics.

[4]  U. Griesmann.  Three-flat test solutions based on simple mirror symmetry. , 2006, Applied optics.

[5]  Absolute sphericity measurement. , 1989, Applied optics.

[6]  Christof Pruss,et al.  Absolute interferometric test of aspheres by use of twin computer-generated holograms. , 2003, Applied optics.

[7]  Hyug-Gyo Rhee,et al.  Azimuthal position error correction algorithm for absolute test of large optical surfaces. , 2006, Optics express.

[8]  J C Wyant,et al.  Absolute testing of flats by using even and odd functions. , 1993, Applied optics.

[9]  Bernard S. Fritz,et al.  Absolute Calibration Of An Optical Flat , 1984 .

[10]  K. Freischlad.  Absolute interferometric testing based on reconstruction of rotational shear. , 2001, Applied optics.

[11]  C. Evans,et al.  Uncertainty estimation for multiposition form error metrology , 1997 .

[12]  D T Moore,et al.  Interference imaging for aspheric surface testing. , 2000, Applied optics.

[13]  C. Evans,et al.  Test optics error removal. , 1996, Applied optics.

[14]  A. Belegundu,et al.  Optimization Concepts and Applications in Engineering , 2011 .

[15]  Hyug-Gyo Rhee,et al.  Improvement of linewidth in laser beam lithographed computer generated hologram. , 2010, Optics express.

[16]  J Grzanna,et al.  Absolute flatness testing by the rotation method with optimal measuring-error compensation. , 1992, Applied optics.

[17]  G Molesini,et al.  Absolute measurement of planarity with Fritz's method: uncertainty evaluation. , 1999, Applied optics.

[18]  Parameswaran Hariharan.  Interferometric testing of optical surfaces: absolute measurements of flatness , 1997 .

[19]  Zensheu Chang,et al.  Extracting the zero-gravity surface figure of a mirror through multiple clockings in a flightlike hexapod mount. , 2009, Applied optics.