| CPC G03F 7/7085 (2013.01) [G03F 1/84 (2013.01); G03F 7/70875 (2013.01)] | 15 Claims |

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1. A method for determining surface parameters of a patterning device, the method comprising:
positioning the patterning device with respect to a path of an exposure radiation beam using a first measurement system and at a first focal plane of a chromatic lens arranged in a second measurement system;
illuminating a part of a surface of the patterning device with radiation through the chromatic lens, the radiation comprising a plurality of wavelengths;
determining a position of the illuminated part in a first and second direction;
collecting at least a portion of radiation reflected by the patterning device through the chromatic lens;
measuring, at a second focal plane of the chromatic lens, an intensity of the collected portion of radiation as a function of wavelength, to obtain spectral information;
determining the surface parameters of the patterning device at the determined position from the spectral information, and
maintaining a relative position of the chromatic lens with respect to the surface of the patterning device without movement during the measuring when obtaining the spectral information.
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