UV-A Blacklight Blue Filter Light Bulbs
The UV-A portion of the ultraviolet spectrum peaks at about 365nm (nanometers). Commonly called blacklights, the UV-A bulbs in this category have the characteristic violet/blue filter to block most visible light. Other ultraviolet blacklight bulbs do not have this blue filter. The applications for the blacklight bulbs below include special effects, stage/studio installations and inspections.
About Filtered UVA Blacklights
Ultraviolet blacklights with a filter operate similarly to unfilted UVA lamps, but the blue/black filter on these bulbs removes most of the visible light output. Phosphors used in the manufacturing of these lamps allow the ultraviolet radiation to pass through. They are used in a wide array of applications.
One of the most common applications for filtered blacklights is special effects lighting. This can include everything from large concerts and club shows to posters with "invisible ink" that glow when exposed to the UV blacklights. Filtered UVA bulbs are used most often in these applications to make the effects more striking by removing much of the visible light.
Document and Currency Inspection
Filtered blacklights can be used to verify currency, passports, rubber stamps, and other identification documents. They can help identify forged documents. For instance, US currency includes a security thread that glows green under ultraviolet blacklights.
These filtered blacklight lamps can be used for identifying organic substances. They are used by veterinarians to check animals for skin infections, and can also be used to identify bed bug waste trails.
Various types of fungi and bacteria fluoresce under UVA light. In addition, UVA lamps can be used to identify antifreeze poisoning, as manufacturers use an additive that causes urine to fluoresce, aiding in quick discovery and treatment.
While many commercial insect traps use unfiltered blacklights, consumer bug zappers often use these filtered UVA lamps. This allows them to be used in outdoor applications to attract insects, while not being distracting to humans. Filtering out the visible light makes the bug zappers less detectable to human eyes.