Imaging apparatus comprising a focus-error and/or tilt detection device.

摘要

An imaging apparatus is described which comprises an imaging system (PL) and a focus detection device for determining a deviation between the image plane of the imaging system and a second plane (WS) on which imaging is to take place. The focus error detection system comprises a radiation source (S) which supplies a beam (bf) having a wide wavelength band, an object grating (G1) and an image grating (G2) which are imaged onto each other via the second plane. In the focus detection system a reference beam (br) which is reflected by the outer surface (RP) of the imaging system can be used in combination or not in combination with the wideband beam and the gratings. By using a number of such focus detection systems a tilt detection device can be realised for detecting the position of the second plane (WS) with respect to the image plane. <IMAGE>