Incorporating news from O plus E magazine, Tokyo
SAITAMAEngineers at Sumita Optical Glass have developed an ultraviolet (UV) sensor that maintains constant characteristics over long periods of time (see figure). Ultraviolet light has become indispensable in manufacturing, its uses ranging from bonding using light-hardened resins to cleaning; the signal from a UV sensor can be used to adjust UV intensity, keeping it constant. However, because UV rays have high energy, the active area of ordinary sensors degrades, making it difficult to monitor UV light over long periods of time.
This new sensor uses a type of wavelength-conversion glass to convert UV light to visible light before measuring the radiation intensity. A small piece of wavelength-conversion glass is affixed to a rod that is inserted into the UV irradiation area. This converts the light to visible light, which is sent to a detector using a fiber light guide. Information on the radiation intensity measured by the detector can be used as feedback to control the light source.
Ultraviolet (UV) sensor contains rare-earth-doped optical glass that converts UV to visible light. The glass does not change characteristics even under prolonged intense UV irradiation. The visible light is transmitted by a fiberoptic cable to a detector. (Photo courtesy of Sumita Optical Glass)
Wavelength-conversion glass is made by incorporating rare-earth ions into optical glass. The ions absorb UV rays and emit light at a different wavelength. The optical glass is highly durable with respect to UV rays, and the characteristics of the rare-earth ions are also resistant to change. The wavelength region that can be observed is from 200 to 380 nm. The sensor head and light guide are heat-resistant to 300°C, while the magnitude of temperature drift is less than 0.1%/°C.
The sensor head is thinner and smaller than a pencil, so just a small corner of the workspace is required for observation. At 70 x 49 x 25 mm3, the amplifier is also very compact, so space issues are not a concern. According to Sumita, the device should have many applications, not only at manufacturing sites, but also in at medical sites where sterilization and sanitation are crucial.
Courtesy O plus E magazine, Tokyo