Abstract: An infrared microscope has an aperture-forming part having a rectangular aperture with variable shape and size. A sample to be analyzed is photographed first and its image is displayed on a display screen. A virtual rectangular image is displayed on the same display screen superposingly on the image of the sample. The shape, size, position and orientation of this virtual rectangular image can be changed according to the positions of points on the display screen specified by a user through an input device such as a mouse. The shape, size, position and orientation of the aperture with respect to the sample are automatically changed so as to match those of the virtual rectangular image with respect to the image of the sample on the display screen.

Abstract: Before a measurement for an infrared analysis of a sample is performed, a measurement area of the sample is set. In the measurement area setting mode, a camera takes the image of the whole sample, and the image is shown on a display. An image of an aperture is superimposed on the image of the sample in the display. When an operator uses a mouse connected to a controller of the infrared microscope to change the width of the image of the aperture on the display, an aperture signal generator generates an aperture signal corresponding to the width of the aperture image. An aperture image signal generator receives the aperture signal and generates an aperture image signal having the width. Thus the image of the sample superimposed on the image of the aperture in the display changes accordingly, by which the operator confirms the measurement area, i.e., the position and width of the aperture, in the sample.