Abstract: A transmission type confocal laser microscope has a transmission side objective lens below a specimen stage, which comprises an objective lens unit which is movable in an optical axis direction and a fixed relay lens unit, wherein movement of the objective lens unit for focus adjustment will not change the optical path after the relay lens unit. The microscope further includes an optical path switch on an optical path in the rear of the transmission side objective lens for switching between the optical path to the concave mirror and another optical path; and a target in a position optically equivalent to the concave mirror, which is illuminated by a light source for adjusting the transmission side objective lens for focusing.

Abstract: An automatic control device for controlling the iris diaphragm in an optical system having lens groups therein, comprising an outer casing adapted to be detachably secured to the optical system surrounding the optical system and an iris diaphragm drive mechanism mounted in the outer casing. The iris drive mechanism includes a drive source in the form of an annular rotary electric motor provided by an annular rotor and an annular stator opposing the annular rotor, said rotor and stator being disposed in the optical axis of the optical system. The electric motor responses to a signal from photometer means of the optical system and rotates the rotor to thereby operate the iris diaphragm.