An optical assembly (1) includes an optical element (2), a mount (3) configured to hold the optical element (2), and a plurality of fastening elements (12) with fastening areas (14) configured to fasten the optical element (2) to the mount (3). The fastening elements (12) bridge an interstice (11) between the optical element (2) and the mount (3), and a purge device (15) produces at least one purge gas flow (16) in the region of the optical element (2) such that the purge gas flow flows around the fastening areas (14) of the fastening elements (12).

A device for optically imaging at least a part of an object, the device having an optical axis and including a two-dimensional first array of first microlenses, having a first side intended to face the object, and a second side, opposite the first side, a two-dimensional second array of second microlenses, each first microlens being aligned with a second microlens on an axis parallel to the optical axis, wherein each first microlens comprises a first catoptric system, and preferably a first catadioptric system.