Understanding Phosphorescent Material — and Why It’s Different from Luminescence
We’ve all heard about phosphorescence, and what most likely comes to mind are the glowing stars children put on bedroom ceilings. This is just one example of a phosphorescent material — others include some glowing paints, markings on safety signage, various types of adhesives, plastics, invisible inks, and the inks used on many types of paper currencies.
With these latter applications, manufacturers and printers that are looking to improve product quality and production automation need an advanced solution for detecting phosphorescence. If you’re researching solutions, you’ve likely come across luminescence sensors such as EMX’s UVX luminescence sensor series. While luminescence and phosphorescence sensors are closely related, the key difference is the type of light energy they’re measuring and how they do it.
Without getting too heavy into the science, phosphorescent materials achieve their prolonged glowing effect because the surface absorbs and re-emits photons at a much slower pace than fluorescence/luminescence (depending on the material, this can be anywhere from milliseconds to days), which re-emits the photon almost instantly. For phosphorescent materials, the energy is significant enough to allow the material to glow.
Comparing Sensors for Luminescence and Sensors for Phosphorescence
Luminescence sensors use a beam of ultraviolet light that causes a fluorescent material to glow. This reaction is detected almost instantly due to the sensor’s rapid detection speed — up to 6 kHz or 6,000 cycles per second. With phosphorescence sensors, that reaction is not what is being measured — instead, the sensor detects the glow after the ultraviolet light beam hits the material.
Companies considering a sensor solution for detecting phosphorescence might initially look at luminescent sensors thinking the sensor will still pick up glow. However, this is not the case. Luminescence sensors typically use a “light on, light off” process to deal with ambient light. Because the phosphorescent material continues to glow, the luminescence sensor will continue to detect the presence of light in the “on” state, thereby failing to complete a cycle.
How to Use Phosphorescence Sensors
This is where some of the usage requirements for phosphorescence sensors come into play. A sensor for detecting phosphorescence must be used in a dark room. This is because any ambient light in a facility or space will be detected (i.e. the sensor does not have a feature called “ambient light subtraction”). Remember, phosphorescence sensors pick up the prolonged glow from a material. If used in a lit area, the phosphorescence sensor won’t produce any readings just as a luminescence sensor wouldn’t when detecting a phosphorescent material.
About the UVX-300P and UVX-300P-FG
EMX Industries, Inc. is one of the pioneers of the phosphorescence sensor. As part of our UVX series, we offer two sensors for phosphorescence — the UVX-300P and the UVX-300P-FG. Both sensors have the following advanced features:
- Lightning-fast 150-microsecond response time for fast-paced automation
- A 2-digit display for signal strength, fast setup, and easy integration
- Light source intensity adjustment, detection threshold, and gain settings
- A metal alloy case and glass lens offer robust construction and reliability
- Includes a discrete PNP/NPN output and an analog output for other systems
- A flexible operating range of 20-350 mm for various applications and setups
- UVX-300P-FG suppresses blue light common in optical brighteners in paper
- Available with a variety of accessories to simplify integration
Don’t Stay in the Dark — Find Out If the UVX-300P/FG Is Right for Your Application
EMX Industries offers complimentary sample testing to help you understand if our sensors are right for your application and environment. The process is simple — just reach out to us when you’re ready, provide some details about your application, and send in a sample of your material. Our expert engineers will get to work testing your material under the optimum settings required by the UVX-300P to determine if it’ll work for you.
You’ll receive a full report describing how the test was performed, what the results were, and any specific usage or integration recommendations (and a few photos if possible). If the sensor isn’t right for your application, we’ll be transparent about that, too.