Last revised: September 25, 2024
Reviewed by: Scott Orlosky, consulting engineer

UV sensors measure the power or intensity of incident ultraviolet (UV) radiation. This form of electromagnetic radiation has shorter wavelengths than visible radiation, but is still longer than x-rays. UV sensors are used for determining exposure to ultraviolet radiation in laboratory or environmental settings. They are transmitters that respond to one type of energy signal by producing energy signals of a different type. Generally, these output signals are electrical signals that are routed directly to an electrical meter for observation and recording. The generated electrical signals from UV sensors can also be sent to an analog-to-digital converter (ADC), and then to a computer with software for generating graphs and reports.

Types of UV Sensors

There are many types of UV sensors. Examples include:

• UV phototubes
• Light sensors
• UV spectrum sensors

UV phototubes are radiation-sensitive sensors that are used for monitoring UV air treatments, UV water treatments, and solar irradiance. Light sensors are general-purpose devices for measuring the intensity of incident light. UV spectrum sensors are charge-coupled devices (CCD) that are used in scientific photography. These UV sensors are also used for measuring the portion of the UV spectrum that sunburns human skin. Ultraviolet light detectors, germicidal UV detectors, and photostability sensors are also commonly available.

Specifications

Selecting UV sensors requires an analysis of specifications such as:

• wavelength range
• accuracy
• power range
• weight
• operating temperature

Wavelength range is the range of wavelengths, in nanometers (nm), that UV sensors can detect. UVA radiation ranges over wavelengths from 315 nm to 400 nm. UVB radiation covers wavelengths from 280 nm to 315 nm. UVC radiation is defined as between 100 nm and 280 nm. Because UVC radiation is more energetic, it is also the most harmful. Accuracy is a measure of how effectively UV sensors measure ultraviolet radiation. Power range and weight are also important parameters to consider, especially for UV sensors that are used in the field. Common operating temperatures range from -20° to 100°; conditions requiring UV sensors below or above these temperatures may need customized engineering.

Applications 

UV sensors are used in many different applications. Examples include pharmaceuticals, automobiles, and robotics. UV sensors are also used in the printing industry for solvent handling and dyeing processes. In addition, UV sensors are also used in the chemical industry for the production, storage, and transportation of chemicals.

UV Sensors FAQs

How do UV sensors work?

UV sensors produce a beam of ultraviolet light that is reflected off a target material in a process called efflorescence. This efflorescence is a way to detect the presence of a UV source. The sensor detects this visible light and converts in into an electrical signal that provides a numerical reading or triggers an indicator.

How do UV sensors compare to other types of sensors?

UV sensors have unique characteristics and applications that differentiate them from other types of sensors. Specifically, UV sensors measure the power or intensity of incident ultraviolet (UV) radiation, typically between 320 and 380 nm. They detect fluorescence rather than reflected light, converting it into an electrical signal for measurement or indication. Meanwhile, other sensors, depending on the type, may measure different physical quantities such as temperature, pressure, humidity, light intensity (visible spectrum), or chemical composition. For example, infrared sensors detect infrared radiation, while photodiodes measure visible light intensity.

What are the advantages of newer UV sensors over older versions?

Newer UV sensors offer a variety of advantages over older versions including a longer operational life – more than 100,000 hours compared to 4,000 hours for older discharge lamps; faster response times; greater sensitivity and range, often through interchangeable lenses; and the ability to detect objects across a conveyor as well as close up.

What are the limitations of UV sensors?

Some limitations of UV sensors include the inability to sense the orientation of objects; potential issues with detecting objects that fluoresce below the factory set detection threshold; and a short range for accurate readings, which can be problematic in dirty environments like wood processing.

How do UV sensors contribute to environmental monitoring?

UV sensors play a crucial role in environmental monitoring by measuring the power or intensity of incident ultraviolet (UV) radiation. Here are some specific ways in which they contribute:

• Ozone layer monitoring: UV sensors help in monitoring the thickness and health of the ozone layer by measuring the amount of UV radiation that reaches the Earth's surface. A thinner ozone layer allows more UV radiation to pass through, which can be detected by these sensors.
• Air quality assessment: UV sensors are used to detect pollutants and other harmful substances in the atmosphere. For example, they can measure the concentration of ozone at ground level, which is a key indicator of air quality.
• Water quality monitoring: UV sensors can be used to detect organic compounds in water bodies. By measuring the UV absorbance of water samples, they help in identifying the presence of pollutants and contaminants.
• Solar radiation monitoring: These sensors are also used to measure the levels of UV radiation from the sun. This data is important for understanding the potential impacts on human health, agriculture, and ecosystems.
• Climate change studies: By providing accurate measurements of UV radiation, UV sensors contribute to climate change research. They help scientists understand the effects of UV radiation on various environmental processes and ecosystems.

How do UV sensors handle different materials with similar fluorescence levels?

UV sensors come with numeric displays and adjustable parameters, allowing operators to set sensitivity thresholds to differentiate between materials with similar fluorescence levels. This feature is particularly useful in applications like spotting adhesives on bright cardboard packaging materials,

References

Design World—Illuminate the Invisible

Electronics360—The Evolution of the Light Bulb

Electronics360—Researchers Reveal How to Make Transparent Sensors

Electronics360—Ultraviolet Light Sensor Monitors for Environmental Health Risks

GlobalSpec—Ultraviolet Light Sensor for Wearables

Image credit:

Sphl / CC BY-SA 3.0