Photometer with LED light source

[0007]In accordance with the present invention, a photometer is provided for measuring the concentration of a chromophore in a fluid. The chromophore absorbs light at a measurement wavelength and absorbs substantially less light at a reference wavelength. The photometer includes a light source having first, second, third and fourth light emitting diodes (LEDs). Each of the first and second LEDs are operable to generate measurement light at the measurement wavelength and each of the third and fourth LEDs are operable to generate reference light at the reference wavelength. The measurement light and the reference light follow an optical path. A sample cell holds the fluid and is positioned relative to the light source such that the optical path passes through the sample cell. A detector is arranged to receive the reference light and the measurement light after having passed through the sample cell. The detector generates at least one signal proportional to the intensity of the reference light and the measurement light received. Centers of the first and second LEDs are respectively arranged in diagonal first and second quadrants defined by perpendicular first and second axes.

[0008]Also provided in accordan

Both tungsten/halogen and deuterium lamps operate at high temperatures and consume a large amount of electric