In a measurement method, the method uses an EUV reflectometer to measure the reflectance of a
test object (PR) reflecting EUV
radiation as a function of the
wavelength of the EUV
radiation and of the
angle of incidence of the EUV
radiation on the reflective surface (OB) of the
test object, the reflectance is measured by means of a first
partial system (TS1) and by means of a second
partial system (TS2) of a
beam shaping unit. The present invention relates to a method for measuring a surface (OB) of a
test object (PR), comprising a first
partial system (TS1) comprising a
monochromator (MC) and being part of a
beam shaping unit (SFE) for imaging an EUV
radiation emission source spot (QF) on an exit gap (SP) of the
monochromator, and a second partial
system (TS2) for imaging the exit gap on the surface (OB) of the test object (PR), the first partial
system (TS1) comprising a
monochromator (MC) and being part of a
beam shaping unit (SFE) for imaging the EUV
radiation emission source spot (QF) on the exit gap (SP) of the monochromator. In this way, a measurement spot (MFL) is generated. According to the invention, the test object (PR) is positioned in a plurality of
degrees of freedom with respect to the measurement beam (STR) such that during operation the measurement beam (STR) impinges on the reflective surface (OB) at a specifiable
angle of incidence in the region of the measurement spot (MFL). A characteristic of the
light beam reflected by the surface of the test object is detected by means of a
detector (DET), wherein a
detector signal representative of the EUV radiation reflected by the test object is generated. The
detector signals are evaluated in order to determine reflectance measurements. In the
beam direction control operation, by means of a reflection
manipulator (MAN) formed by the first mirror (S1) and at least one second mirror (S2) of the second partial
system located downstream thereof in the
beam direction, and changing the position of the measurement spot on the surface of the test object by controlled modification of the
beam direction of the measurement beam (STR) by means of these mirrors displaced in a mutually coordinated manner in at least one rigid degree of freedom in response to a
control signal from the
control unit.