The LCRT-2005-S from Gigahertz-Optik Inc., Newburyport, MA, is a portable instrument to measure the inline transmission of windows and glass with and without reflection-reducing coatings. The device consists of a uniform light source, receiver, and controller. Both detectors for light source reference and transmittance are BTS256 diode array sensors. A compact CCD camera built into the receiver supports aligning the receiver and light source. The reference detector spectral measurement data are used to calculate standard CIE Illuminant A or D65 or monochromatic transmission at specified wavelengths.