초록 ▼

A narrow gap or unevenness of a surface of a specimen is measured by utilizing the tunnel effect of a light wave reflected at a boundary plane on the condition of total reflection. A laser beam emitted from a laser source is reflected at a surface of a prism on the condition of total reflection in t

A narrow gap or unevenness of a surface of a specimen is measured by utilizing the tunnel effect of a light wave reflected at a boundary plane on the condition of total reflection. A laser beam emitted from a laser source is reflected at a surface of a prism on the condition of total reflection in terms of geometrical optics. If a gap between the surface of the prism and the specimen is about the wavelength of the laser beam, part of the laser beam is transmitted into the specimen, and the intensity of the transmitted beam depends on the gap width. A portion of the laser beam is reflected at the boundary plane back into the prism. Therefore, the gap can be measured by measuring the transmittance of the laser beam and comparing the same with the calculated relation between the transmittance and the gap calculated in advance. In practice, the gap width is determined by measuring intensity of the reflected laser beam in the presence of the gap and comparing it to the intensity of the reflected laser beam in the absence of the gap, i.e, when the specimen surface is more than several wavelengths away from the reflecting surface.

대표청구항 ▼

A device for measuring a gap between a surface of a specimen and a specific member comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmission reflector having a reflecting surface comprising said specific member located substantia

A device for measuring a gap between a surface of a specimen and a specific member comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmission reflector having a reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across the gap for reflecting said laser beam at said reflecting surface such that geometric optical total reflection occurs; a photosensor for measuring intensity of said laser beam reflected by said reflecting surface of said reflector; a base on which said laser source, said reflector, and said photosensor are mounted; a first driving mechanism for relatively moving at least one of said base and said specimen in a first direction defining said gap; and gap determining means for comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell\s equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam.