mike's si reflectivity graph

jeff's si reflectivity graph

The data for the Simox wafers has a much greater variance than the silicon wafers. The procedure is the same for the Simox wafers, but the reflectivity curves are sinusoidally shaped, rather than asymptotically decreasing like it is for silicon and germanium. This peculiarity can have advantages in cases where you want a substance to be reflective only under selected colors.

simox graph

Recording data for the reticles demanded a new procedure. After getting normalization data, the reticles are placed upon the aluminum mirror. Data was taken from the reticles in a few different orientations. The reticle was measured with the chrome rulings pointed vertically with respect to the slit of light. The rulings were also pointed horizontally and diagonally (45 degree angle). In each instance, the reticle was positioned such that the maximum amount of chrome was visible under the slit. This method was only important for the wide ruled reticles, since the rulings on the finer reticles were significantly smaller than the slit and did not influence the results.

The reticles are made with different rulings, ranging from the rough 50 lines per inch up to 5000 lines per inch (shown below). The best flat-line data was produced by the finely ruled reticles (750 lines per inch or greater). Under 500 lines per inch, the data became choppy and noisy. This could be due to the non-uniformity of the chrome. For each of the data recordings, the experiment was performed with the chrome rulings facing up, closest to the microscope objective.

reticle 5000