Coupling clamp for contactless sensor unit

A contactless sensing unit for a coordinate measuring machine or machine tool, the contactless sensing unit comprising an optical probe device, a coupling element for mechanical connection to a complementary coupling element of the coordinate measuring machine or machine tool, and a housing retaining the optical probe device, the housing being mechanically connected to the coupling element,

• wherein the optical probe device comprises a cylindrical body and an optical objective at a distal end of a lower portion of said probe device for sensing a surface of a workpiece, and
• wherein the contactless sensing unit further comprises an elastic C-shaped ring of steel or of an alloy clamping circumferentially the cylindrical body of the optical probe device, the elastic ring being fastened to a fastening portion of the housing allowing a radial position adjustment of the clamped optical probe device and the elastic ring has a force regulating screw across a gap of the elastic C-shaped ring for adjusting a clamping force of the elastic C-shaped ring on the cylindrical body.