Abstract: A microlithographic projection exposure apparatus (1) comprises an illumination system (4) with an illumination optics (5) for illuminating an illumination field in a reticle plane (6). The illumination optics (5) further includes a light distribution device (12a) which comprises a light deflection array (12) of separate elements and an optical assembly (21, 23 to 26) which converts the light intensity distribution defined by the light distribution device (12a) in a first plane (19) of the illumination optics (5) into an illumination angle distribution in the reticle plane (6). Downstream of an output coupling device (17), which is arranged in the light path between the light deflection array (12) and the reticle plane (6), a space and time resolving detection device (30) is exposed to outcoupled illumination light (31) in such a way that the detection device (30) detects a light intensity distribution corresponding to the light intensity distribution in the first plane (19).