What is the function of a spectrophotometer?
Spectrophotometry is a scientific technique used to measure the intensity of light either transmitted through or reflected from gas, liquid or solid samples. In transmission, which is directly related to absorbance per Beer's law, spectrophotometry is the technique that measures how much a substance absorbs a beam of light passing through it. By measuring the intensity at each wavelength, a spectrum is created and this can tell us much information about the sample through which the light passed.
In reflectance, spectrophotometry measures the amount of light that is reflected from an opaque specimen. Again a spectrum is created by measuring the intensity at each wavelength of light. All this can be done with a spectrophotometer.
The spectrophotometer is an optical instrument for measuring the intensity of light relative to wavelength. Electromagnetic energy, collected from the sample, enters the device through the aperture (yellow line) and is separated into its component wavelengths by the holographic grating. Simply put, the grating acts to separate each color from the white light. The separated light is then focused onto a CCD array detector where the intensity of each wavelength (or each color if in the visible region) is then measured by a pixel of the array. The CCD is then read-off to a computer and the result is a spectrum which displays the intensity of each wavelength of light.