Measuring device with deformable optical element

The invention relates to an optical surveying device (11) with a base (1) for positioning the surveying device (11) and an aiming unit (3) rotatable relative to the base (1) about two axes (7, 8), which defines a target axis (9) for aiming at a target object (40) to be surveyed. The aiming unit (3) has a first beam path (10z) for emitting optical radiation (10) in the direction of the target object (40) to be surveyed and a second beam path (10y) for receiving a portion of the optical radiation (10) reflected back from the target object (40) through an optoelectronic receiving element. [0002] According to the invention, at least one of the beam paths (10z, 10y) has an optical element (30) which is designed with an optically transparent, deformable volumetric body (63) which has at least one boundary surface (63g) facing a medium with an optical refractive index differing from that of the volumetric body (63). [0003] The boundary surface (63g) is deformable by means of several electrical control signals (31a, 31b, 31c, 31d) such that the optical refractive properties of the element are variably differently in at least two non-coinciding directions (31a, 31b, 31c, 31d).