Figure 3. Transmittance of CaF₂ windows as measured on BL-4 vs. calculations from commonly-used values of optical constants. Data provided by R. Gupta and P. Shaw, Optical Technology Division.

Measured transmittance (ranging from 0.6 to 0.95) vs. wavelength (from 100 nm to 300 nm) is shown for two windows, repsectively, 2 mm and 20 mm thick; these results are nearly indentical. For wavelengths below 200 nm, the theoretical values deviate from those measured: this deviation is as high as about 30 % at wavelngths of 130 nm.

Technical Highlights 1999