| 摘要 |
A wavefront correction system is provided which uses an achromatic null lens to correct various aberrations introduced in a spherical wavefront when the wavefront is reflected off a non-spherical surface, particularly a parabola. Chromatic aberration, including spherochromatism, is corrected over a relatively wide bandwidth. When used in conjunction with an interferometer and a variable wavelength source, the wavefront correction system provides adequate means for determining relative position errors of the segments of a segmented mirror. The derivative of the phase error is obtained with wavelength by measuring interference for different wavelengths of light. This allows position errors of greater than one half wavelength to be accurately measured.
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