Abstract: Optical apparatus includes a source light a reflector having a reflecting face on one side facing the source of light to receive light therefrom, a small interruption in the reflecting face, and a sampling device located on the opposite side of the reflector aligned with the small interruption for extracting a sample of the light received by the reflecting face.

Abstract: Electro-optical display apparatus includes a plurality of modular units each having a projector for receiving electrical signals, converting them to optical images, and projecting the optical images via an optical projection system onto a screen. The modular units are arranged in a side-by-side array such as to produce a combined display on the screen. A calibration system detects distortions in the combined display caused by the projection system of each modular unit and modifies the electrical signals applied to the projector of each modular unit to correct the combined display with respect to the detected distortions.