Abstract: The level of a laser beam is controlled to the maximum level detectable by a sensor, and light transmitted through the pattern is normalized with branched light. The laser beam level is made up for variations, and noise at zero and saturation levels are removed. Data thus can be taken out, in which noise in edge portions is always at a constant level. It is thus possible to increase the pattern image accuracy and obtain sharper image.

Abstract: The level of a laser beam is controlled to the maximum level detectable by a sensor, and light transmitted through the pattern is normalized with branched light. The laser beam level is made up for variations, and noise at zero and saturation levels are removed. Data thus can be taken out, in which noise in edge portions is always at a constant level. It is thus possible to increase the pattern image accuracy and obtain sharper image.

Abstract: The level of a laser beam is controlled to the maximum level detectable by a sensor, and light transmitted through the pattern is normalized with branched light. The laser beam level is made up for variations, and noise at zero and saturation levels are removed. Data thus can be taken out, in which noise in edge portions is always at a constant level. It is thus possible to increase the pattern image accuracy and obtain sharper image.

Abstract: A focal point detecting apparatus for an objective lens is disclosed for inspecting whether or not the focal point of the objective lens used in an electron microscope, an optical inspecting apparatus, a laser processing apparatus, etc. is positioned on a surface of a target object. The focal point detecting apparatus comprises for entering an optical beam for detecting a focal point from a position deviant from an optical axis of an objective lens to a surface of a target object to be inspected through at least the objective lens; and two two-split sensors on which the optical beam reflected from the surface of the target object so as to pass again through the objective lens is converged by at least a condenser lens. The two two-split sensors are arranged at the same optical inclination in front of and behind the position on which the reflected optical beam is converged by the condenser lens when the focal point of the objective lens is positioned on the surface of the target object.