Patent Number: 
Section: abstract

Disclosed is a measuring apparatus for measuring the position, size and/or shape of a light convergent point of an EUV light source. In one preferred form, the apparatus includes a light receiving device for receiving EUV light diverging from a light convergent point, an optical system for directing the EUV light toward the light receiving device, a light blocking member disposed in a portion of light path for the EUV light and having a plurality of openings, and a system for detecting a spatial distribution of the EUV light at the light convergent point, on the basis of reception of EUV light by the light receiving device. In another preferred from, the apparatus includes a light receiving device for receiving EUV light diverging from a light convergent point, a gas filter disposed in a portion of a light path of the EUV light and being filled with a predetermined gas, and a system for detecting a spatial distribution of the EUV light at the light convergent point, on the basis of the reception of EUV light by the light receiving device.