We have developed a particular combination of elements and devices which enables the portability of a scanning electron microscope. The method includes: determining a target subject; determining whether the target subject exists in a moving image photographing domain; determining whether a condition of temporarily stopping recording of a moving image based on whether the target subject exists is satisfied; and temporarily stopping the recording of a moving image when the condition is satisfied. This additional fiber is chosen to have a slope for its wavelength versus dispersion behavior that is the negative of that for the transmission fiber. Thereafter, the space defined between the opposite films is sealed, and air or gas is then removed from the sealed space so as to compact the material arranged therein and so as to form a blank.