Understanding UV Luminescence and Phosphorescence
Before deciding on any sensor solutions to detect UV luminescence or phosphorescence, it’s important to know the differences between them. While you might think that any sensor capable of detecting UV light would work, it’s how the light is emitted that determines which sensor you’ll need.
- Luminescence — A material that luminesces will glow when hit with a beam of ultraviolet light. This reaction is quick and, depending on the material, can dissipate rapidly. Thus, a UV luminescence sensor that can detect the light at high speed (think 6,000 cycles per second) is crucial. Luminescence sensors can be used in many environments because they have a feature called ambient light subtraction, which helps the sensor avoid false readings based on other light.
- Phosphorescence — Whereas UV luminescence sensors detect the reaction almost immediately, phosphorescent materials absorb and re-emit light at a slower pace, causing a prolonged glow. In these instances, a sensor that detects the light emission over time is needed. A different environment — i.e. a dark room — will be needed as well to prevent ambient light from being detected.
Applications for UV Luminescence and Phosphorescence Sensors
Finding the right UV luminescence or phosphorescence sensor typically involves an assessment of your unique application. While many sensors could do the trick, it’s important to select the right one based on the material, your production speed and environment, and whether other materials will be verified down the road. Below are several common applications along with sensors that have been used for success.
Adhesives, Glues, Inks & Oils
As long as a luminescent tracer has been added to the adhesive, glue, ink, tape, or oil, a UV luminescence sensor can be used to verify its presence. Common examples of adhesives include automotive parts, medical equipment, and packaging. In these applications, verifying that a part has indeed received the necessary adhesive or lubricant is important for quality control and to confirm various manufacturing processes.
Paper & Packaging
On the packaging side, invisible inks help to ensure that materials are genuine and to provide traceability back to the manufacturer. Inks on the packaging itself, registration marks, and other markings also require verification. Just as above, as long as they have a UV tracer in their composition, a UV luminescence sensor can be used to confirm presence. Conversely, a phosphorescence sensor can be used with paper. Optical brighteners used in paper production often produce a glow when hit with UV light, allowing for their detection.
Labels & Tamper-Evident Seals
Labels, much like paper and packaging, can contain optical brighteners as well as inks and adhesives that need to be verified on incredibly high-speed lines. The same goes for tamper-evident seals, specifically shrink bands, which contain optical brighteners. A few different sensor types could be used in these applications, but if you’re simply trying to verify presence while processing tens of thousands (if not hundreds of thousands) of products per hour, a high-speed UV luminescence sensor will work wonders here.
UV Marks & Lumber
A variety of industries utilize various markings made with different materials for quality control purposes. An example comes from the lumber industry, where UV crayons are used to mark wood pieces or products that contain defects, have a fungicide applied to them, need certain spots cut, or for other purposes. As these products move along a production line, a UV luminescence sensor can be used to rapidly identify them, send a signal, and initiate some downstream action.
These Are Just the Beginning of What a UV Luminescence Sensor Can Detect
Threads, textiles, silks, paint, and more are also detectable with a luminescence or phosphorescence sensor depending on the material and what aspect of them will emit light when struck with a UV beam. As mentioned above, there are a number of sensor models available to you, but what matters most is that you find one that is uniquely suited to your production needs and working environment.
EMX Industries offers complimentary sample testing to help you find the right UV luminescence sensor for your goals. Simply tell us what you’re looking to achieve, send in a sample of your target material, and we’ll provide a written report (with photos as possible) detailing the ideal sensor and how it performed. We’ll help you choose a model with the right sensitivity, calibration settings, operating distance, and more. We’ll also make recommendations on how to ideally integrate the sensor to ensure consistently accurate readings to maximize results.