The instrumentation consists of a sophisticated synchronously demodulated detection and amplifier system for maximum discrimination against spurious illumination and electronic noise. The instrument operates in full room light and maintains accuracy.

The instrument has an electronically chopped LED as the source of the illumination. The LED is a solid state emitter that is operated at derated power and has a long life. There are no moving parts. The Transmissometer can operate with the photopic spectral response of the eyes or other wavelengths when desired.

The transmissometer is simple to calibrate and use. For small values of transmission, the decade gain can be increased from X1 to X10 or X100.

Various applications include measuring transmission of:

1. Visible transmitting and infrared reflecting film for heat reduction coating for windows.
2. Polarizing film.
3. Crossed polarizing film to verify the extinction ratio.
4. Aluminized film used for bags for perishable food to increase shelf life.
5. Metallic film for use in anti-static bags for electronic components.
6. Film for magnetic tape.