Transmission Measurements of Films - "Direct" and "Total"
What is the difference between Total Transmission and Direct Transmission? Two types of transmission measurements are used when measuring thin films. The 1st is at the sphere (total transmission), and the 2nd is at the lens (direct transmission). The unit is designed to operate with the Specular Component included [SCI] with the CE7000A set for Large Area View [LAV].
'Total' transmission should be performed when the sample to be measured is hazy or cloudy. A cloudy sample will transmit light at more angles than a sample that is not hazy. A total transmission reading will make certain that all transmitted light is measured for an accurate reading.
'Direct' transmission should be performed when the sample to be measured is clear. A clear sample will transmit light at only one angle, called the "direct component angle." A direct transmission reading will make certain that the light transmitted at this angle is measured for an accurate reading.