Abstract: A portion of a surface of a sample body is arranged to receive an incident optical beam having an optical intensity I.sub.0. On an opposing surface of the sample body is located an optical detector which senses the intensity I of the resulting optical radiation emerging from the opposing surface of the sample body. In order to measure the thickness t of the sample body, a thickness gauge is located either at another portion of the surface of the sample body or on the optical detector.

Abstract: The thermal resistivities W.sub.s (=1/.kappa..sub.s) of electrically insulating, crystalline or polycrystalline samples under test (SUTs), all comprising host material such as CVD diamond, can be determined rather quickly once the thermal resistivities W=1/.kappa. of at least two other host crystalline or polycrystalline bodies B.sub.1 and B.sub.2 comprising the same host material as that of the SUTs, and containing the same type of impurity or combination of impurities as the SUTs, are measured by some other technique. These determinations of these thermal resistivities W.sub.s of the SUTs thus require only the measurements of the optical absorptivities .alpha..sub.1 and .alpha..sub.2 and of the thermal resistivities W.sub.1 and W.sub.2, respectively, of at least each of the two other bodies B.sub.1 and B.sub.2 and only of the optical absorptivities .alpha..sub.s of each of the SUTs by such other technique. These determinations of W.sub.

Abstract: A technique that involves selective removal of material from a surface of a polycrystalline diamond (polyD) film such that a non-planar surface results. Exemplarily the technique is used to form polyD optical elements, e.g., convex or concave lenses, or Fresnel lenses, including arrays of such lenses. The technique involves maintaining on appropriately shaped hot template body in intimate contact with a polyD surface for a time (e.g., in the range 1-1000 hours) sufficient to result in formation of the desired feature in the polyD surface. The template body involves a rare earth metal (La and Ce are preferred), Mn and/or Fe, and the temperature is below the melting temperature of the template body. Removal of "spent" template material by, e.g., chemical etching and finishing of the polyD feature, e.g., by laser ablation and/or polishing, are contemplated.

Abstract: A diamond body, such as a CVD diamond film, is etched by immersion of the body in a molten or partially molten metal, such as the rare earth metal La or Ce. While the body is being etched, various portions of a major surface of the body can be protected for various time durations by masks against the etching--whereby, after dicing the body, the resulting dies can be used as submounts for lasers with feedback.

Abstract: A diamond body, such as a CVD diamond film, is thinned by placing the body--at an elevated temperature and under pressure--in contact with a molten or partially molten alloy of a rare earth metal and a metallic impurity that lowers the melting point of the rare earth metal. Typically, the rare earth metal is cerium and the impurity is nickel.The pressure is typically less than approximately 0.2 MPa (Mega Pascal), preferably less than approximately 0.02 MPa, and the temperature is within a range whose lower limit is approximately 100 C. degrees below the melting point of the alloy of the rare earth plus impurity metal.

Abstract: In order to measure the in-plane thermal conductivity of a sample plate, the plate is placed in a prefabricated device containing (1) a pair of thermocouples, (2) a source of heat flow into the plate, (3) a heat sink of the heat flow having an open cavity, (4) a taut membrane, on which the source of heat flow and the thermocouples are bonded, located on the resilient filling, (5) a resilient filling of thermally insulating material located underneath the membrane, in the cavity of the heat sink, and (6) a thermally insulating medium covering the plate and exerting a compressive force on it.