Abstract: A method of producing uniform metal mirror surfaces which are harder than e starting material. A three step machining process produces uniform metal mirror surfaces without polishing defects or lack of spatial uniformity from previous polishing methods. The surface is first machined in the normal manner for diamond turning. The second machining process requires the rake angle to be made negative to the extent of approximately 30.degree.. This machining process creates plastic deformation in the surface material. The final step requires machining material in the top rake angle of from -5.degree. to +5.degree. which provides the uniform surface of regular diamond machining. An alternate method only needs a single cut at an intermediate rake angle.

Abstract: A device for measuring energy absorptance of a sample material. A temperature controlled enclosure, in which a sample is suspended, is placed in an evacuated container. Calibration is accomplished by means of a known power dissipation in the sample. The sample material is irradiated by an energy beam of known power and a temperature rise is compared to the calibration temperature rise. Means for scanning the sample is also provided.

Abstract: An optical notch filter having a suspension of small absorbing particles which blocks a narrow band of frequencies. The small absorbent particles are suspended as a colloidal system which can have either a solid, liquid or gas as host material. The absorbing particles can be incorporated in a solid matrix as a transmission filter or used on the surface of a mirror as a reflection filter. The filter can be tuned by an externally applied electric field or by applying hydrostatic pressure.