OptoSigma Corp. has developed a family of standard and custom parabolic mirrors, which are available in on- and off-axis configurations up to 16 in. in diameter. They are hand-polished from large blanks of fine-annealed low-expansion glass to precise focal lengths. Finished to a surface accuracy of 1/10 wave, the mirrors are supplied with a measured interferogram. Protected aluminum, enhanced silver, gold or broadband dielectric thin-film coatings are available.