What is in the material that makes the lens dark? Is it the same halide (i think the spelling is correct) crystals that are used in glass lenses?
What is in the material that makes the lens dark? Is it the same halide (i think the spelling is correct) crystals that are used in glass lenses?
Hello Optidonn,
Transitions Optical (PPG Industries) developed photochromic compounds for non glass lenses from organic photochromic families that are used in Transitions Lenses.
Since 1964, Silver Halides (Inorganic chemistry) were and are still used in glass lenses. The halides do not work with plastics.
Original Transitions used Indlino Spiro Oxazines. Since the mid 90's we developed hyperchromics called Diaryl Napthopyrans.
PPG has identified over 1,000 compounds from these two families. There are over 100 US patents covering these compounds.
I hope this helps.
Both the Transitions and PPG Industries web sites have good information on photochromic compounds and how they work.
regards,
Jim
Jim Schafer
Retired From PPG Industries/
Transitions Optical, Inc.
When you win, say nothing. When you lose, say even less.
Paul Brown
i went to PPG's web page and read about photosol. Is this what is used in transitions? Is its description of how it gets dark (carbon-oxygen bond) a good way of describing how gets dark? and one more question and i swaer thats it (for now;) ) how is it applied? is it laminated on? or is some kind of coating?
Thanks
Hello Optidonn,
Transitions® Lenses are created from propietary, patented processes.
Standard index (1.50, CR-600 series) and mid index (1.54 to 1.56, the Spectralite® Velocity™, Ormex® and High-X brand materials) are imbibed. Imbibition (developed in the 1980's and commercialized in 1990) is the driving of the photochromic compounds into the surface of the lens. The photochromics are permanently imbedded into the surface at a uniform depth of 150 to 200 microns..this is about 20 times deeper than average lab tint. The compounds are part of the lens and cannot be scratched or peeled off.
Polycarbonate, 1.6-1.67 High Index and Trivex® Lenses are Trans-bonded™. Poly and Hi Index lens materials offer excellent physical characteristics but function poorly for hosting photochromic compounds. Because of this we developed Trans-bonding. These lens materials receive propietary surface treatments and a series of ophthalmic grade layers, which provide outstanding adhesion, scratch resistance and optical purity along with outstanding photochromic performance. Since 1998, Over 16 miilion lenses have been sold in the US using this technology.
regards,
Jim
Jim Schafer
Retired From PPG Industries/
Transitions Optical, Inc.
When you win, say nothing. When you lose, say even less.
Paul Brown
thank you very much:cheers:
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