Industry Terms Optical Gloss Measured on a glossmeter. This instrument has an incandescent light source and a photosensitive receptor and responds to visible light. Light shines onto the sample at a specified 60º angle. Some of this light is reflected onto the photosensitive receptor. The fraction of the original light that is reflected is the gloss of the sample. (ASTM D-523) Haze Luminous transmittance of transparent plastics. In this test, haze of a specimen is defined as the percentage of transmitted light which, in passing through the specimen, deviates more than 2.5 deg from the incident beam by forward scattering. Luminous transmittance is defined as the ratio of transmitted to incident light. These qualities are considered in most applications for transparent plastics. They form a basis for directly comparing the transparency of various grades and types of plastics. A hazemeter and/or a recording spectrophotometer are used in the test. (ASTM D-1003)