Measuring instrument and method for determining geometric properties of profile sections

A measuring instrument for determining at least one geometric property of a profile section, comprising

• an assembly which produces at least one first and one second light beam, wherein a beam direction of the first light beam is different from a beam direction of the second light beam,
• a retro-reflecting surface, which is arranged with respect to a light source of the assembly so that at least the first light beam is incident at least partially on the retro-reflecting surface, and
• a recording device which determines a light intensity distribution in a transverse dimension of at least a portion of a first reflected light beam produced when the first light beam is reflected by the retro-reflecting surface, said recording device also determining a light intensity distribution in the transverse dimension of at least a portion of the second light beam or of at least a portion of a second reflected light beam produced when the second light beam is reflected by the retro-reflecting surface or by another retro-reflecting surface,
• wherein the light assembly produces the at least one first and one second divergent light beam, the measuring instrument further comprising a concave mirror on which the divergent light beams are incident in such a way that the light beams reflected by the concave mirror are light beams with parallel light.

A method for determining a geometric property of an object, comprising the steps of:

• producing with an assembly a first collimated light beam and a second collimated light beam having different beam directions,
• holding the object to be measured between the assembly and a retro-reflecting surface in such a way that the first collimated light beam is incident partially on the retro-reflecting surface and partially on the object to be measured,
• measuring with a recording device at a first location a light intensity distribution in a transverse dimension of at least a portion of a first reflected light beam produced when the first collimated light beam is reflected by the retro-reflecting surface, and measuring with the recording device at a second location a light intensity distribution in the transverse dimension of the second light beam or of at least a portion of a second reflected light beam produced when the second collimated light beam is reflected by the retro-reflecting surface, and
• determining from the light intensity distribution measured at the first and second location the geometric property of the object.