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Technical Articles: Background Information On The EverBright Filter

Technical Information on the Background for a Long-Lasting SW Filter

Don Newsome

Don Newsome, founder of UV SYSTEMS, Inc., gives the inside story of how a simple, focused desire, and a lifetime of research and inventiveness have led to the all-new, EverBright SW Filter that delivers 75% constant transmission at 254 nm with negligible solarization after 1000-plus test hours.

 

 

 


I have been interested in fluorescent minerals and ultraviolet lights since 1950.

In 1967, two years after I graduated from college, I visited a small museum/rock shop in Oregon that had a fluorescent display. The first thing I noticed was that the SW fluorescent minerals were very dim, almost non-fluorescent.  It was obvious that the SW filters had solarized so much that their UV light was useless.  

In that moment, I saw with my own eyes that solarization was robbing ultraviolet light of exposing the stunning, natural, and colorful fluorescence of minerals that untold numbers of people—from hobbyist to museum directors and everyone in between—could enjoy for a lifetime.

That day in that tiny rock shop marked the beginning of a life-long commitment and research, development that has allowed me to solve the solarization problem with the all-new EverBright SW Filter.

The technically minded will appreciate what I was up against: Solarization is a chemical process that causes the filter to lose its 254.7 nm transmission with SW exposure time. Solarization means fluorescence declines, so does the vibrancy (and thus the enjoyment of) a mineral’s colors.

Glass filters, made by Corning Glass Works since about 1934 called #9863, would solarize in as little as 200 to 500 hours of exposure to SW 253.7 nm UV.  The amount of solarization depends on the amount of SW to which the filters are exposed.  High SW power means shorter filter life.  (At that time, all practical SW UV lights used germicidal mercury [Hg] vapor low-pressure hot cathode UV lamps {some call them bulbs}, or low-pressure cold cathode UV lamps).  

In 1983 UVP, Inc. of San Gabriel, CA, in connection with Hoya Optics in Japan, invented the SW UVG filter which had less solarization and therefore longer life than Corning’s #9863 being used at that time.  Because UVP, Inc. had an exclusive on the UVG filters, Hoya could not sell that filter glass to anyone else.  So Hoya made a slight change to their glass formation and sold it as U-325C filter glass. That allowed other users of SW filters to buy the U-325C filter.  

Raytech Industries, one of UVP, Inc.’s competitors, started using the U-325C filter and called it a “Color Blaze Filter,” advertising it as a “lifetime filter.”

I did not think any SW filter would last a “lifetime”.  So, in 1984 I formed a nine-member Research Committee as part of the Fluorescent Mineral Society (FMS) to determine which brand of SW filter would last the longest.  We came up with a plan and test procedure called “Solarization Experiment 1985”. 

By 1969 my sights were set on developing a new SW filter that would build upon the strengths of our SuperBright and TripleBright UV lights and in effect conquer the threat solarization for hobbyists, everywhere. With each strategic step, this vision moved closer and closer to reality:

  • In 2000 I conducted testing on SW liquid filters. I tested a liquid filter concept in 2002 and again in 2009. Conclusion: SW liquid filters are not practical, especially for handheld UV lights.
  • In 2016, I conducted tests, using front surface 254 nm reflecting mirrors to obtain a useful SW filter. After exhaustive tests, I concluded that the assembly was too big but mostly it did not reflect enough of the 254 nm to be practical.
  • At every turn, I wouldn’t take “No” for surpassing the performance and longevity of traditional glass SW filters.
  • From 2019, I doggedly researched several thin-film companies, investigating, purchasing, and testing SW thin-film filters. Significant time and money went into evaluating one company’s SW thin-film filter, only to determine it was not completely satisfactory. But I keep going.

In 1992 I founded UV SYSTEMS to supply SW filters and lamps to fluorescent hobbyists.

To that end, I committed to use premier industry instruments to validate true, accurate measures for all products that carry the name “UV SYSTEMS.” These instruments include:

  • Five UV radiometers to measure the SW, MW, and LW transmission of filters.
  • An International Light Technology ITL5000 radiometer with two UV-C sensors
  • A UV-B sensor
  • A UV-A sensor for UV-A and visible light measurements
  • Two spectrophotometers and accessories
  • Ocean Optics Maya 2000Pro spectrophotometer to measure wavelengths. 

[The International Light Technology company was recently purchased by Ocean Insight (the new name for Ocean Optics)].

Finally, in 2023, after three years of experiments, assessments and re-evaluations with a trusted, proven  thin-film company, UV SYSTEMS is proud to announce a breakthrough filter, the EverBright*.   

This one-of-a-kind product meets all five criteria required for a superior SW filter:

  • high initial transmission of SW UV [at 253.7nm]
  • no solarization or the slowest solarization rate
  • minimum transmission of visible light
  • strong physical attributes [will not break easily or cloud up with humidity, etc.],
  • the need to be producible at a commercially acceptable yield rate [example: if only every other batch was any good the yield would not be acceptable],

And this is why our company, UV SYSTEMS is proud to announce the launch of the EverBright, the only new SW filter on the market:

  • Greater than 75% constant transmission at 254 nm (compared to less than 50% for the popular Japanese filter after 100 hours)
  • No detectable solarization after over 1000 test hours (the popular Hoya U-325C Japanese filter had significant solarization with transmission of less than 24%)
  • Superior at blocking any visible light. Specifically engineered to have less than ½ % transmission at each of the Hg visible emission lines.
  • The transmission at 405nm is so low that you do not see the blue reflection light off of a non-fluorescent mineral like you would with a U-325C filter.
  • Over 100 thin films are deposited on an optical grade high silica substrate.
  • There are thin films on both sides of the filter.
  • Multiple EverBright filters can be fabricated in a single batch.

* Patent Pending on that filter and UV lamp combination.


info@uvsystems.com   uvsytems.com

Cell phone: (206) 818-1084

UV SYSTEMS, Inc. 16605 127th Ave SE, Renton, WA  98058

Supplying High-Quality UV Lighting to North America and the World