Title:
FILM THICKNESS MEASURING INSTRUMENT
Document Type and Number:
Japanese Patent JPH01131405
Kind Code:
A
Abstract:
PURPOSE:To automatically measure and correct the refractive index of an object of measurement such as an opaque film which has a coefficient of absorption by finding the refractive index from the output ratio of a P and an S component which provide the maximum value of an interference waveform and the output ratio of a P and an S component which provide the minimum value. CONSTITUTION:Light from a light source 1 is projected on the object 3 of measurement like the opaque film having the coefficient of absorption and the light which is transmitted through it is split into a P-polarized component and an S-polarized component By a polarizing plate 5 which is rotated by a driving means. Then they are diffracted spectrally by a prism 7 and incident on a CCD 9 to detect the intensity of interference fringe patterns as to the P and S components. The output of the CCD 9 is processed by an arithmetic means 10 as specified to find the refractive index and film thickness 10 the object 3. Consequently, the refractive index is found by utilizing the ratio of the P and S components which provide the maximum value and the ratio of the P and S components which provide the minimum value, so even if the kind and refractive index of the object 3 are changed, the refractive index is corrected automatically at all times and the accurate film thickness can be measured.
Inventors:
IDE TOSHIHIKO
AIKAWA KOSEI
AIKAWA KOSEI
Application Number:
JP29086887A
Publication Date:
May 24, 1989
Filing Date:
November 17, 1987
Export Citation:
Assignee:
CHINO CORP
International Classes:
G01B11/06; (IPC1-7): G01B11/06