Portable photometer.

摘要

A portable photometer comprises a light emitting diode and a d.c. powered measuring circuit. The light emitting diode is mounted in an assembly (23) including a collimator to ensure that only a narrow beam of light is emitted which will not impinge on the sides of a well containing a solution to be tested. The assembly is also provided with a locating member for engagement with a tray (19) containing the wells to ensure that the tip of the collimator is an accurately defined distance from the bottom of the well. The light passing through a solution is detected by a photo detector and collimator assembly (22) located below the tray and in register with the light emitting diode and collimator assembly. The assembly (23) is brought into an operative position by the action of closing a lid (12) to form light tight compartment within which the measurements are made.