Optical sensors: varieties and working principle

Optical sensors are devices that are designed to control the distance and position, determine color and contrast marks, as well as solve other technological problems. Instruments are mainly used in industrial equipment.

By the way of functioning optical sensors are divided into three types.

Devices that reflect from the object are capable of emitting and receiving light that deviates from the object located in the zone of their action. A certain amount of light is reflected from the target and, when hit on the sensor, establishes an appropriate logical level. The magnitude of the trigger zone depends largely on the type of device, dimensions, color, curvature of the surface, roughness and other parameters of the object. In its design, the receiver and the radiator are present in one housing.

Optical sensors reflecting from the retroreflector receive and emit light that comes from a special reflector, and when the beam is interrupted by an object, an appropriate signal appears at the output. The scope of such a device depends on the state of the environment that surrounds the sensor and the object (fog, smoke, dust, etc.). In this device, the emitter and receiver are also housed in the same housing.

The third type includes optical sensors that have a separately located receiver and light source. These elements are mounted opposite each other along one axis. The object falling into the area of the light stream causes its interruption, and at the output, respectively, the logical level changes.

Light elements of devices can work at different wavelengths, which include infrared or visible (laser) light, as well as other indicators of color labels.

In its design, the optical sensor consists of an emitter that generates light in different ranges, as well as a receiver that distinguishes the signal emitted by the first element. Both components of the device are located in one and in different cases.

At the heart of the work of devices is the change in optical radiation when an opaque object appears in the zone of action. When the device is turned on, an optical beam is received, received through a reflector or reflected from the object. Then, a digital or analog signal is generated at the output of the sensor , having a different logic, which is then used by the executive device or the registration circuit.

Fiber-optic sensors have a different sensitivity zone, which ranges from a few centimeters to hundreds of meters.

It is most convenient to use diffuse devices, which independently trigger on the object. Most optical sensors allow you to change the sensitivity settings and indexing the output status, and self-tuning models are also produced.

The market is represented by many manufacturers. For example, devices manufactured by AUTONICS are particularly popular. They are distinguished by great variety, low price and high reliability.