OPTICAL MEASURING DEVICE

An optical measuring device for measuring the thickness or a height of a step of a workpiece (5) comprises a pair of deviation measuring means (16), a pulse generating circuit (17) for producing pulse signals which control the deviation measuring means (16) so that they operate alternately, and signal processing means (17) for adding outputs of the deviation measuring means (16). The deviation measuring means each include an optical position detecting element (8) having a light receiving plane disposed perpendicular to an optical axis having a predetermined angle with respect to an optical axis of a light beam irradiating the workpiece (5), a laser light source (3) for emitting the light beam, and a drive circuit (2) responsive to the pulse signals to control the laser light source (3). The deviation measuring means (16) being controlled so that their optical position detecting elements (8) are irradiated alternately with the light beam and so that the deviation measuring means (16) are operable only when their own laser light source (3) is emitting the light beam.