PURPOSE: To make high the precision of the inspection of a mask pattern by a system wherein a fluorescent substance emitting fluorescence by the application of an excitation light is disposed on one side of a mask and the fluorescence generated by the excitation light is detected by a detector through the mask.
CONSTITUTION: A light 121 generated from a light source 102 and passing through a condenser lens 103 is made to pass through a first filter 108 so as to be turned into an excitation light 122 having a wavelength which tends to generate fluorescence. Thereafter, the direction of this light is shifted by a translucent mirror 109, and then the light is made to pass through a transparent portion of a mask 101 and irradiate a fluorescent substance 107, wherefrom fluorescence 123 is generated. Next, the fluorescence 123 is reduced to fluorescence 125 alone through the translucent mirror 109, an imaging lens 105 and a second filter 110, and the latter is imaged on a detector 106 and subjected to photoelectric transfer. Thereby the existence of a minute point (x) and a transparent minute point (y) on the mask 101 is detected, without fail, as (a) and (b) on detection signal levels. According to this system, both a minute opaque point and a transparent point can be detected.
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HARA YASUHIKO
UJIIE NORIAKI
HASHIMOTO YUTAKA
