RESUMEN
A model is presented for predicting the temperature rise in an opaque material during the absorption of a moderately short pulse of energy. Experimental verification of the model employing a pulsed ruby laser and a cadmium telluride plate is described. Two distinct damage thresholds were noted: (1) at modest energy levels plastic deformation occurred, and (2) the higher energies resulted in surface melting.
RESUMEN
The stress-optic coefficients of ZnSe have been measured at room temperature; Twyman-Green and Fizeau interferometers were used in conjunction with a four-point loading device. Test specimens were rectangular parallelepipeds of chemically vapor-deposited material prepared by Raytheon Corporation. Measurements were made with the optical propagation parallel to the deposition direction, and optical scanning and computer analysis were employed to determine fringe positions to an accuracy of better than 0.01 of a fringe spacing. The experimental values for pi(11) and pi(12) are -1.48 +/- 0.05 x 10(-12) m(2)/N and +0.22 +/- 0.05 x 10(-12) m(2)/N, respectively.
RESUMEN
An experiment was performed to determine the change in refractive index and absorptivity upon x radiation of several optical materials. Exposure to a radiation dose of 10(5) rad produced measurable changes at lambda = 0.5330 microm in the index of refraction and at lambda = 0.5000, microm in the absorption coefficient of ~5.8 x 10(-6) and ~0.1 cm(-1) for calcium fluoride. Optical glasses exhibited changes of ~5.8 x 10(-6) and ~1.1 cm(-1) for LaK 8, ~4.3 x 10(-6) and ~1.7 cm(-1) for PSK 53, ~5.1 x 10(-6) and ~1.4 cm(-1) for FK 50, and ~6.0 x 10(-6) and ~1.0 cm(-1) for SF 8. A change in the absorption coefficient of the optical glass KzFS 5 of ~0.52 cm(-1) was measured. Changes induced in an SiO(2) (Suprasil 2B) control sample were below measurement capability.
RESUMEN
Procedures are described to figure optical surfaces by ion polishing. Fused silica, ULE, and Cer-Vit were employed as substrate materials. The sputtering yields for these materials were: 1.9 (150-keV(40) Ar(+)), 1.86 (150-keV (40)Ar(+)), and 3.7 (80-keV (126)Xe(+)) atoms/ion, respectively. The optical scatter, at lambda = 632.8 nm, was measured to be 0.06%, which is comparable to good surfaces prepared by conventional lap techniques. The rms surface error was reduced from 0.05lambda to 0.01lambda over the central 0.12-m aperture of a 0.2-m diam fused silica flat by ion polishing with 150-keV (40)Ar(+). Based on this experience, the design of a manufacturing facility is discussed.
RESUMEN
The high strength-to-weight ratio and thermal diffusivity of beryllium are very attractive to the optical system designer for many critical applications. In order to realize the potential advantages of beryllium, it is necessary to have mirror blanks figured to optical tolerances which are also dimensionally stable over the life of the system. As part of a program to improve the dimensional stability of beryllium, we have cataloged the properties of both Kanigen-coated and bare beryllium mirrors. The results presented in this report indicate the bare beryllium is to be preferred over Kanigen-coated beryllium for precision optical surfaces.
RESUMEN
This paper presents a technique to measure the relative scatter of x-ray reflecting surfaces. Scatter measurements were performed on fused silica, Cer-Vit, beryllium, Kanigen, steel, and silicon. Fused silica surfaces consistently produced the least scatter, while beryllium produced the greatest scatter (4x that of silica), with the other materials being intermediate and approximately equivalent (about 2x as much scatter as silica).
RESUMEN
The controlled removal of material from the surface of insulators has been observed by using a positive ion beam. In the energy range 0.5-2.0 MeV the sputtering yield was observed to be unity. The application of this technique to the manufacture of high quality optical surfaces is discussed.