Korea Research Institute of Standards and Science

Jong-Han Jin

Jae-Wan Kim

Jong-Ahn Kim

Chu-Shik Kang

Tae-Bong Eom

Provided are a thickness measuring apparatus and a thickness measuring method. The thickness measuring method includes irradiating a first laser beam of a first wavelength &#x3bb;to a transparent substrate and measuring intensity of the first laser beam transmitting through the transparent substrate; irradiating a second laser beam of a second wavelength &#x3bb;to the transparent substrate and measuring intensity of the second laser beam transmitting through the transparent substrate; and extracting a rotation angle on a Lissajous graph using the first and second laser beams transmitting through the transparent substrate. A phase difference between adjacent rays by multiple internal reflection of the first laser beam and a phase difference between adjacent rays by multiple internal reflection of the second laser beam is maintained at &#x3c0;/2.

Thickness measuring apparatus and thickness measuring method

Provided are an absolute position measurement method, an absolute position measurement apparatus, and a scale. The scale includes a scale pattern formed by replacing repeatedly arranged pseudo-random-codes with a sequence of a linear feedback shift register of N stages using a first symbol with first width representing a first state and a second symbol with second width representing a second state. The first is divided into two or more first symbol areas of different structures, and the second symbol is divided into two or more second symbol areas of different structures. There is at least one overlap area in which the first symbol and the second symbol overlap each other to have the same structure.

Growing community of inventors

Daejeon, South Korea

Jong-Han Jin