Patent ID: 9291921
Filing Date: 2016-03-22
CPC Classification: G03F

Claim Text:
1. A detection apparatus which detects an object to be detected, the apparatus comprising: an illumination system configured to illuminate the object with light containing a first wavelength range and a second wavelength range different from the first wavelength range; a detector configured to detect light from the object illuminated by the illumination system; and an optical member configured to set a transmittance for light in the first wavelength range and a transmittance for light in the second wavelength range to be different from each other, thereby reducing a difference between an intensity value of the light which has the first wavelength range and is detected by the detector and an intensity value of the light which has the second wavelength range and is detected by the detector, wherein the detection apparatus has, as operation modes, a detection mode in which the detection apparatus detects the object, and a preparation mode in which the detection apparatus makes preparations to detect the object, in the preparation mode, the illumination system illuminates the object with light in each of a plurality of divided wavelength ranges obtained by dividing a wavelength range including the first wavelength range and the second wavelength range, and the detector detects the light in each of the plurality of divided wavelength ranges from the object, the optical member includes a plurality of optical elements which have different transmittances and are exchangeably placed in an optical path of the light, and the detection apparatus further comprises a control unit configured to obtain an intensity ratio in the wavelength range from an intensity value of the light in each of the plurality of divided wavelength ranges detected by the detector, select an optical element, which reduces the difference, from the plurality of optical elements based on the intensity ratio, and place the selected optical element in the optical path in the detection mode.