Abstract: The traffic situation may be recorded by way of at least two detection cameras (2, 3) which are to be arranged at a distance (15) to one another on a vehicle (1). Their detection regions (11, 12) overlap (13), by which means at least one reference point (R) of the surroundings and/or recognition point of at least one second vehicle may be triangulated (T), e.g. by way of photogrammetry. After an accident, the behaviour of one or more vehicles (1) may be reconstructed. By way of the three-dimensional, temporally cycled detection, apart from the respective spatial position, the speed, the speed direction, direction changes, acceleration- and braking manoeuvres as well as intrinsic rotations of the individual vehicles about their centres of gravity may be visible and measured in a scaled manner. And this is all possible without having a multitude of sensors on the vehicles.

Abstract: The device for collecting the radiation of a light source (20) within a concave mirror comprises a cylindrical or rotationally symmetrical parabolic or elliptical reflector (10'), which is covered with a curved or planar retroreflector (40) having an opening (42). The retroreflector (40) returns part of the light into the vicinity of the source (20) and brings about, due to the partial transparency of this area, that an intense, quasi-parallel light beam can be coupled out through opening (42). After passing through a monochromator element (31), this light can e.g. be supplied to a gas measuring cell (68). The optical efficiency of the device is increased by the concave mirror (57) in a shape supplementing reflector (10', 10"). The measuring signal can be determined by means of a light detector or a microphone (69). In the latter case, an acoustically decoupling gas exchange device is required, which can e.g. be realized by means of capillaries filled with the liquid (75, 75').