The detector measures the intensity of the transmitted light, comparing it to the light that entered the sample. Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. When light passes through a sample, the molecules in the sample absorb some of it, and the rest passes through.
An optical power meter (OPM) is a device used to measure the power in an signal. The term usually refers to a device for testing average power in systems. Other general purpose light power measuring devices are usually called,, power meters (can be sensors or ), or lux meters. A typical optical power meter consists of a , measuring and display. The sens.