Transmission measurements were made on samples of acrylic, polystyrene, styrene-acrylic copolymer (N.A.S.), polymethyl pentene (TPX), polysulfone, polycarbonate, and Trogamid; molded windows of 5.08-mm thickness were measured over the range 0.4-40.0 microm. All these injection-moldable materials appear to be usable in the visible region, and have surprisingly similar transmission profiles from 1.0 microm to 2.0 microm. Polystyrene and TPX possess several potentially useful transmission windows in the middle-wavelength and long-wavelength infrared regions, particularly TPX. The potential of these materials as substitutes for expensive crystalline materials in infrared application is discussed. The possibility that other thermoplastic materials may offer similar opportunities is also presented.

No abstract

The optical elements of a cassegrainian telescope are commonly tested individually, with their axes in a horizontal position. When these optical elements are inserted in the telescope, the resulting imagery is often disappointing. The quality of the imagery in the telescope may be predicted more accurately if the primary and secondary mirrors, with their axes in the vertical position, are tested against each other with the aid of null compensating reimaging optics. An example is given to illustrate the application of the technique.

Accurate electromechanical gauging of steep aspheric profiles is often complicated by the complexity of the elationship between the locus of the probe tip center of curvature and the probe tip/asphere contact point. Solving for the contact point is usually done in an iterative manner, which is a fairly laborious computing chore. But since a considerable amount of sag information is conventionally produced by the lens design program generating the aspheric surface, it is possible to shortcut the process by using these data to solve directly for the probe tip coordinates as a function of the aspheric prescription.