A photodetector is described along with corresponding materials, systems, and methods. The pawl is pivotable about a pawl bearing and includes a latching toothing which in a locked state of the latching fitting engages into a counter latching toothing of a locking piece connected to the second part. The particles are used to obtain a compact by press forming. When the light emitter fails, it is disconnected from the cable and replaced with a working light emitter. At least one transport media is supported on the rollers for movement along the path of travel in response to rotation of the roller by the motor.