Calibration of a Photometric Standard for Hard Dot Area measurement

Discussed are the specifications for a Photometric Standard of Hard Dot Area. Mathematical approximations have determined the desired pattern and frequency to be; cross hatch and 100 lines/in. respectively. When measuring the Photometric Standard, deviation from the actual area is attributed to micromotion in the aperture and diffraction in the Densichron 3885d (Sargent - Welch Scientific Co.). The desired specifications in the Photometric Standard allow precise measurements of ± 5% area. A Hard Dot Area Meter was designed and constructed, which simulates a photometric method that theoretically eliminates deviation from the actual area measured. It was statistically tested against microscopic measurements of the Photometric Standard