| 摘要 |
An optical multiply reflecting arrangement, useful for example for a smoke density meter, features a light source or sender 12 at one end of a measuring section 11 and a first retroreflecting device, in the form of a lens 13 in front of a retroreflecting in element 14 which produces sideways deflection of a light beam, at the opposite end of the measuring section 11 for returning the light beam in the general direction of the light source 12. Light deflecting elements such as optical wedges 18, 18' can be moved into the beam path in front of the retroreflecting device and further retroreflecting devices 16, 16' and/or light transmitting elements can be moved into position at the sender side. Depending on the combination of optical elements used at the light source and in front of the first retroreflecting device 13, 14 it is possible to choose between two-fold, four-fold, six-fold or multiple passages of the light beam through the measuring section. Strategically positioned photodetectors 41, 41' can detect the emergent light beam. <IMAGE> |
