The colorimeter is usually used to measure the concentration of a known solute in a given solution with the help of the Beer-Lambert law, which postulates that the absorption and concentration of a liquid sample are directly proportional. To analyze color against an existing standard, the colorimeter sends an illuminate through a liquid sample.
The colorimeter was invented in the year 1870 by Louis J Duboscq. In the 1940’s, Richard Hunter introduced a tri-stimulus model, Lab, which is scaled to achieve near uniform spacing of perceived color differences. At that time many scientists involved with color measurement were working on uniform color scales. There were several permutations of the Hunter L, a, b color scale before the current formulas were released in 1966.
The L,a,b color scale views color in a similar manner to which the human eye sees color.
• L scale: Light vs. dark where a low number (0-50) indicates dark and a high number (51-100) indicates light.
• a scale: Red vs. green where a positive number indicates red and a negative number indicates green.
• b scale: Yellow vs. blue where a positive number indicates yellow and a negative number indicates blue.
There are two different types of colorimeters:
- Color densitometers: Measure the density of primary colors.
- Color photometers: Measure color transmission and reflection.
Colorimeters are typically used to compare the results of a new sample to an existing one. Common colorimeter applications include monitoring the growth of a yeast or bacterial culture, assessing beverage color and measuring ink colors.
Colorimeter
