Optimal calibration laboratory test process for spectrophotometer calibration standards ASTM E 925 And OIML R 135 Uses. At least 5 point calibration wavelengths using filters Holmium Oxide Glass Filter AndDidymium Glass Filter And the solution Holmium Oxide In HClO4Absorption photometry area visible in 3 of the 5 wavelengths using filters Neutral-Density Glass Absorption photometry in the ultraviolet region of 2 to 6 and 4 wavelengths using the solution Potassium Dichromate, The light added to the 3 wavelengths is done. If the client application and the absorption wavelength photometry and repeatability of the test will be added to the above resolution.