Dept. of Medical Technology, Kunsan Vocational Junior College
The term photometric mesurement was originally defined as measurement of light intensity of multiple wavelengths, while spectrophotometric measurements formerly meant mesurement of light intenisty in a much narrower wavelength range. It has recently become common usage to refer to instruments that use filters for isolation of part of the spectrum as photometers or colorimeters, whereas instruments that use gratings and or prisms are called spectrophotometers. The range of light measured is no longer a valid distinction between colorimeters and spectrophotometers. Electromagnetic radiation includes radiant energy from short wavelength gamma rays to wavelength radio waves. Frequently, a white light source for the visible region or a deuterium source for ultraviolet light wil provide the wavelengths used. The wavelength of light is defined as the distance between peaks as the light is envisioned to travel in a wavelike manner.