• A light meter is one method for measuring light.light meter image by Paul Moore from Fotolia.com
  
  Light is a form of electro-magnetic radiation whose wavelength is visible to the human eye. It can be characterized by its speed, intensity, wavelength and frequency. It exists in the form of packets/photons of both waves and particles. Light can be measured using various equipment depending on the light factor of interest.
  
  

Lux Meter

• A lux meter is also referred to as a light meter. This equipment consists of a body, a light sensor (photo cell) and display. The role of a lux meter is to measure illumination in terms of luxes. A lux represents the total amount of light that falls on a surface that is located one foot away from where the light source is, as it falls on a square meter of the surface. Illuminated light which strikes the photo cell is converted to electric energy which is read by the light meter and calculated to its appropriate value. The results are measurements of different combined light wavelengths, which are then displayed as either analog or digital measurements or through video. These different light color wavelengths are measured by their temperatures in degrees Kelvin.
  
  

Spectrophotometers

• A spectrophotometer is an instrument that is used to measure the amount of light of a specific wavelength which passes through a material. This light is equivalent to the concentration of the material taking in the light. This instrument consists of a spectrometer whose purpose is to produce light of desired wavelength. The second part is the photometer which is used to measure the intensity and amount of light. The use of a galvanometer gives signals of the amount of light as the color of liquid in use changes.
  
  

Goniophotometer

• A goniophotometer is an instrument that is used to measure the spatial distribution of the source of radiation thereby displaying photometric properties of the visible light at defined angles. The word goniophotometers is a Greek word derived from gonio which means angle and photometer which means light. This instrument is mainly used in automotive and lighting industries. It measures luminance, intensity distribution, luminous flux, color coordinates, color temperatures and retro-reflection.