Cassegrainian-type reflecting objectives are useful as in-line imaging devices for fast spectrometer systems. They are inherently free from chromatic aberrations and may be corrected for spherical aberration. A particularly simple design, consisting of two mirrors with oppositely equal curvatures, is possible when unit magnification is desired. This system has zero third-order spherical aberration, and all other aberrations are small also. Its main disadvantage is the loss due to the central obstruction of the beam, amounting to about 28% exclusive of reflection losses.
© 1974 Optical Society of America
Original Manuscript: March 8, 1974
Published: November 1, 1974
Klaus D. Mielenz, "Spherically Corrected Reflecting Objective for Unit Magnification," Appl. Opt. 13, 2580-2584 (1974)