Abstract: Light emitted from a light source (22) is used through a light projection optical system (23) to perform coaxial down-emission lighting on a measurement target (36). Light reflected by the measurement target (36) is formed on a photo-detector (26) through an image formation optical system (24). Along its optical path, a spectroscope (25) is provided for converting an image impinging on the photo-detector (26) into a spectroscopic image having a predetermined wavelength band. A measurement point extraction portion (32) in a signal processing portion (28) determines a predeterm film thickness measurement point from an image picked up by the photo-detector (26), extracts an image signal at the film thickness measurement point, and transmits t to film thickness operation portion (33). The film thickness operation portion (33) measured film thickness of a thin film, which is the measurement target (36), from this signal.

Abstract: Light emitted from a light source 22 is used through a light projection optical system 23 to perform coaxial down-emission lighting on a measurement target 36. Light reflected by the measurement target 36 is formed on a photo-detector 26 through an image formation optical system 24. Along its optical path, a spectroscope 25 is provided for converting an image impinging on the photo-detector 26 into a spectroscopic image having a predetermined wavelength band. A measurement point extraction portion 32 in a signal processing portion 28 determines a predetermined film thickness measurement point from an image picked up by the photo-detector 26, extracts an image signal at the film thickness measurement point, and transmits t to film thickness operation portion 33. The film thickness operation portion 33 measured film thickness of a thin film, which is the measurement target 36, from this signal.

Abstract: Each of a detection sample object and a non-detection sample object is illuminated with S-polarization light, for instance. S-polarization light and P-polarization light reflected from each sample object are detected by different photodetecting elements. Glossiness values and light quantities of the detection and non-detection sample objects are judged based on detection outputs of the photodetecting elements, and a glossiness difference and a light quantity difference are calculated. An evaluation function having at least one of the glossiness and the light quantity as a variable is determined by using the glossiness difference and the light quantity difference. Thresholds for object discrimination are calculated based on evaluation function values of the detection and non-detection sample objects.