What Is a Photoelectric Sensor? Functions and Application Areas

Photoelectric sensors use optoelectronic devices as transducers. They detect non-electrical quantities that directly change light, such as light intensity, illumination, radiation thermometry and gas composition analysis; they also detect other non-electrical quantities that convert to light changes, such as part diameter, surface roughness, strain, displacement, vibration, speed, acceleration, object shape and operating status. Photoelectric sensors provide non-contact detection, fast response and reliable performance, and are widely used in industrial automation and robotics. Emerging optoelectronic devices continue to open new application possibilities for photoelectric sensing.

Photoelectric Sensors for Dust Monitoring

Industrial dust control is a key environmental protection task. To eliminate industrial dust pollution, emission must be monitored, displayed automatically and alarmed when limits are exceeded. Flue dust turbidity is detected by measuring light transmission changes through the flue. When turbidity increases, absorption and scattering by particles reduce light received by the detector; the detector's output signal thus reflects turbidity changes.

Photoelectric Sensors and Directed-Energy Threats

Photoelectric sensors are sensitive to infrared and visible radiation and therefore can be vulnerable to laser attacks. Electronic systems and sensors themselves may be disrupted by laser-induced thermal and electromagnetic noise. Laser weapons can "blind" sensors with appropriate energy, causing loss of detection or tracking. Because sensors play critical roles on the battlefield and are susceptible to laser interference, they are potential targets for low-energy directed-energy attacks.

Automatic Meter Reading Applications

Advances in microelectronics, sensors, computing and communications enable automatic meter reading using photoelectric sensors. A rotating aluminum disk in an electric meter driven by eddy currents and magnetic fields can be converted to pulses by a photoelectric sensor: a dark mark on the bright disk produces pulses as it rotates. After optical coupling and isolation, pulses are counted by a CPU for meter reading. Optical isolation prevents interference from entering the microcontroller, enabling reliable automatic reading systems when combined with suitable transmission methods.

Photoelectric Sensors for Color Detection

Any color can be synthesized from RGB primary colors. By placing three photodiodes with red, green and blue filters in the optical path, one can obtain the RGB component values and thus determine color. Because photodiodes have different spectral sensitivities, circuit gains must be adjusted for correction. Photoelectric sensors convert measured variations into optical signals and then into electrical signals via optoelectronic elements. Atonm's CL2 color sensor series features:

1. Easy one-button operation with delay function;

2. 8-channel output supporting up to 4 simultaneous color detections;

3. Color recognition of over 3000 varieties with precise micro-difference detection;

4. Detection modes using brightness, color, or brightness+color;

5. Triple 16-bit RGB computation with independent color LEDs and 16-bit conversion in the receiver to ensure stable detection despite vibration or surface variations; applicable to solids and liquids.