Question

1.)

a.) What procedures could you use to calibrate a sensor that is only required to provide approximate measurements of liquid level?

b.) What is the principal advantage of an optical sensor? Discuss the mode of operation of the two main types of optical sensors

Answer 1

1)a) Liquid level sensors can be processed using a pair of bundle probe which is based on the fiber-optic displacement sensor. The working mechanism of the sensor is to detect the displacement in the reflector which is attached to a membrane (reflector displacement device or RDD) due to changes in the liquid level. The displacement of reflector is detected through the changes in the intensity of reflected light from reflector into an optical fiber receives the light. The other optical fiber acts as a transmitter of light.

b) Optical sensors work by detecting the waves or photons of light, which includes light in the visible, IR, and UV spectral regions. They operate by measuring a change in light intensity related to light emission or absorption. They can also measure phase changes occurring in light beams due to interaction or interference.They are widely used in industrial applications for measuring liquids and material levels in tanks or in factory production lines to detect the presence or absence of objects

The two main types of optical sensors are:-

Photodetector sensors are based on the principle of photoconductivity, where the target material changes its conductivity in the presence or absence of light. Sensors are sensitive for a given spectral region from UV to IR.

Infrared sensors employs an infrared light source, such as a light-emitting diode (LED) or laser diode, which projects a beam of light that gets detected at a separate detector (photoelectric cells, photodiodes, or phototransistors). An object that passes through the beam disrupts the received signal at the detector. An alternative configuration is reflectance-based detection, where the source and detector are located in the same enclosure. Light from the IR source is reflected from an object as it moves into the sensor’s field of detection. The amount of light received at the detector depends upon the reflectivity of the object surface. Infrared sensors can be used as counters, proximity sensors (as with automatic doors), or to identify the presence of people or other mobile objects under day or night conditions.