The invention relates to a measuring system (1) that is suitable in particular for determining reflection characteristics of solar mirror materials, comprising a mirror holder (17) for receiving a mirror material sample (19), a radiation detector (23) having an image sensor (25) and reception optics (27) for receiving light reflected by the mirror material sample (19), a cap (3) having an inner space (5) and a mirrored inner surface (7), wherein the mirrored inner surface (7) is designed in a semi-ellipsoid manner and has a first focal point (11) and a second focal point (13), wherein the first and the second focal point (11, 13) are arranged in the inner space (5) of the cap (3), wherein the mirror material sample (19) can be arranged in the first focal point (11) via the mirror holder (17) and the reception optics (27) of the radiation detector (23) is arranged in the second focal point (13), comprising a light source (35) and a radiation coupler (39) connected to the light source for producing a light beam (31) directed toward the mirror material sample (19), wherein the radiation input coupler (39) is arranged on a guide device (43) for guiding the radiation coupler (39) along a predetermined guide track (45), and wherein the cap (3) has at least one gap (29) or at least one transparent region, via which the light beam (31) can be introduced into the inner space (5) of the cap (3).