Pericentric lens
Pericentric lenses (peri-Greek: περί- "all around") are special lenses in metrology . In contrast to conventional (entocentric, from the Greek entós "within") lenses, the object-side beam path is not divergent, but convergent. This makes it possible to observe objects from several directions at the same time through one lens.
Object- side telecentric lenses (tele-Greek: τηλε = far) represent the borderline case between conventional lenses (object-side divergent) and pericentric lenses (object-side convergent). The required size of the front lens is even larger than with telecentric lenses, that is, significantly larger than the Item size. The image angle of the object shown is greater than 180 ° and in practice reaches values of up to about 300 °. These lenses are not to be confused with wide-angle lenses or fisheye lenses .
These lenses are often constructed as a catadioptric system .