Abstract: A laser scanning microscope includes an acousto-optic element or an electro-optic element in an illumination optical system which introduces a laser beam from a laser beam source of the laser scanning microscope into a microscope. The laser scanning microscope further includes a beam expander disposed between the laser beam source and the acousto-optic element or the electro-optic element.

Abstract: The invention provides a multiphoton-excitation observation apparatus comprising a light-source unit for emitting pulsed laser light; an observation apparatus main unit for irradiating a specimen with laser light emitted from the light-source unit and observing fluorescence emitted from the specimen; an incidence adjusting device, disposed between the light-source unit and the observation apparatus main unit, for adjusting the beam diameter of the laser light emitted from the light-source unit; and a control apparatus for controlling the incidence-adjusting unit according to the depth of an observation plane in the specimen.

Abstract: A microscope apparatus that can observe into the interior of a specimen and that can apply an optical stimulus over a wide area within a short period of time is provided. The microscope apparatus comprises at least one observation scanning optical system including a laser light source for emitting observation laser light, an objective lens, and a scanning optical system for two-dimensionally scanning the observation laser light in a predetermined examination plane of the specimen via the objective lens; and at least one stimulus optical system which includes a lamp light source for emitting light having a wavelength used for optical stimulation and which irradiates the specimen with the light emitted from the lamp light source.

Abstract: A laser scanning microscope includes an acousto-optic element or an electro-optic element in an illumination optical system which introduces a laser beam from a laser beam source of the laser scanning microscope into a microscope. The laser scanning microscope further includes a beam expander disposed between the laser beam source and the acousto-optic element or the electro-optic element.