Often, such a construction can not be performed due to space constraints. For these cases the sensors are designed reflectors. It is usually light transmitter is reflected from the triplet reflector back to the receiver. Because the transmitter and receiver are in one case, the entire structure becomes much easier. Since light must pass a double way, this principle is also suitable for recognition, even transparent media. In some cases it is impossible to place even a reflector.
Then there is the possibility to apply the principle of radar. The light emitted by the transmitter is reflected directly from the object itself. Of course, you can imagine, that this requires a very high level of knowledge and experience of designing devices to reliably detect even objects that have a critical surface, for example, black or little mirror. This often requires a reliable suppression of background noise. Leuze electronic offers for the whole range of different models that suppress the background.
Examples of problems that I have given above can be solved by DIP sensors. But there are many cases when you really need to measure the distance. For example, to determine the diameter of the object or to determine the exact position. To solve these problems especially fit our optical distance sensors, for example, ODS 96. This laser device has a measuring range up to 5000 mm with millimeter precision. To complete the review of applications, glance at the printed industry. Printing presses are expensive and very expensive. In the process of printing in the printing mechanism should not get two sheets of paper, because then require very costly repairs.