In the test of the light transmittance, the incident angle of point light is not all right angle, light refraction will make the light transmittance greater, but this problem will not appear if we adopt the parallel light transmittance meter. Linshang LS116 parallel light transmittance meter is equipped with parallel source, which can accurately measure the light transmittance of thick glass.
As we all know, Refraction is the change in direction of wave propagation due to a change in its transmission medium.
In testing the light transmittance of glass, we calculate by dividing the intensity of light through the intensity of the original light.
As shown in the figure, only the light in the center with vertical incidence doesn’t change the direction of wave propagation, but other light beam is reflected when it change its transmission medium, the light source was gathered so the detector will receive more light. If there is no glass between the light source and detector, the detector will receive less light intensity. Therefore, when the light pass through the glass, the light intensity received by detector will be greater than the light intensity received by detector which is directly pass through the air.
However, the vertical incidence of parallel light source does not change the direction when change the transmission medium, so the light intensity received by LS116 parallel light transmittance meter is equal to the actual light intensity pass through the glass.
Therefore, the data of parallel light transmittance meter is more accurate than point light transmittance meter.
Linshang LS116 light transmittance meter has adopted the parallel white light source(380-760nm), which can be used to test all kinds of glass including extra thick glass. LS116 light transmittance meter can store 9 groups of data and calculate the maximum, minimum and average values. In addition, LS116 parallel light transmittance meter conforms to the CIE visual function standard, and the data can be ensured pass the inspection of the National Measurement Institute.