Abstract: An apparatus comprising a circular ruling engine having a supporting means oscillatable in a controlled manner with a substrate section on said supporting means and means for lifting and lowering a ruling means to rule said substrate section to generate a grating pattern from a number of grating patterns to produce an off-axis grating section. Also disclosed is a method for forming off-axis grating sections.

Abstract: Disclosed is a method and apparatus for optically testing cylindrical surfaces in which a collimated beam of monochromatic light is directed to a variably spaced linear grating which produces two first order cylindrical wavefronts: one, a converging beam in the blaze direction and, two, a diverging beam in an antiblaze direction. The blaze direction beam converges into a line focus. Either a concave or convex cylindrical mirror may be positioned with its axis at that line focus in the appropriate part of the beam to return the rays along their original path to the grating where they interfere with the antiblaze wavefront. By locating a screen of any suitable type in the path of the antiblaze beam, a fringe pattern representing the figure quality of the cylindrical surface under test is formed on the screen. Both concave and convex, coated and uncoated, cylindrical surfaces can be tested by this method and apparatus.

Abstract: A spectrophotometric system includes an optical device for providing an optical path from a radiation generating means to a radiation receiving means. The optical device includes a substantially opaque layer which defines first and second coplanar face regions having different optical functions.