jeudi 19 mars 2015
Optically Correct Snowboard Goggles - Lens Design Vs. Real world
Posted on 11:56 by Immigration
d
Hi guys,
There has been a lot of awesome discussion lately about snowboard goggles and optical quality and I wanted to add some info.
All dual pane goggles have four optical surfaces. The inside and the outside of each of the two lenses. The lenses are of course curved. In a perfect world a curved lens would have no thickness and such a lens would "bend" no incoming light. In the real world, lenses (even thin lenses) do have thickness and if not adjusted for they would "bend" light. For this reason the inner curvature and outer curvature of each lens needs to be different. The free space between the two lenses also needs to be accounted for so each lens needs to have its own subtly different curvatures. That sounds difficult, but as the design of the production process is software driven, that part is actually easily accomplished. We live in cool times!
So, optically corrected lenses are perfect right? Well, theoretically yes. But...in terms of real world functionality this will be overridden by other factors. The big one is you. Goggles by design bend and twist. They need to do so to fit a variety of faces and also to deal with normal motion and of course impacts. The foam (and adhesive) that is used to separate the two lenses also needs to flex. So, the relationships between the curvatures mentioned above is A. Never the same for any two people (faces) B. constantly changing (throughout the day and over time as the structures of the goggle wear). For these reasons even optically correct goggles will always "bend" light and the degree to which this happens will vary greatly from rider to rider.
Polycarbonate is used by the major brands as the lens material. There are many trade names used for Polycarbonate. It is a great material in that it is very impact resistant and heat resistant and it has terrific optical properties. On the downside it scratches very easily. Multiple coatings and finishes are also used on snowboard goggles. Anything applied to the Polycarbonate lens impacts optical quality. Multi million dollar machines are used to apply these coatings. The plating machinery that is used to apply the "mirrored" multi color fade finishes is straight out of sci fi. The control required to apply these materials in depths that need to be even, attractive and varied in color is mind blowing. The depth of these finishes is measured in microns (millionths of a meter). Again, that sounds rad and it is...but...in every instance these finishes are very scratch sensitive. That refers to both the plating and the fog proofing. I mention this because even though the initial coatings are robotically applied at amazing tolerances, in the real world they can be degraded far more easily than I would like. This directly impacts optical quality. So on one hand we have these awesome materials that were developed in large by NASA for space visors and on the other hand we have a product that can be degraded by paper towel.
STOKED!
There has been a lot of awesome discussion lately about snowboard goggles and optical quality and I wanted to add some info.
All dual pane goggles have four optical surfaces. The inside and the outside of each of the two lenses. The lenses are of course curved. In a perfect world a curved lens would have no thickness and such a lens would "bend" no incoming light. In the real world, lenses (even thin lenses) do have thickness and if not adjusted for they would "bend" light. For this reason the inner curvature and outer curvature of each lens needs to be different. The free space between the two lenses also needs to be accounted for so each lens needs to have its own subtly different curvatures. That sounds difficult, but as the design of the production process is software driven, that part is actually easily accomplished. We live in cool times!
So, optically corrected lenses are perfect right? Well, theoretically yes. But...in terms of real world functionality this will be overridden by other factors. The big one is you. Goggles by design bend and twist. They need to do so to fit a variety of faces and also to deal with normal motion and of course impacts. The foam (and adhesive) that is used to separate the two lenses also needs to flex. So, the relationships between the curvatures mentioned above is A. Never the same for any two people (faces) B. constantly changing (throughout the day and over time as the structures of the goggle wear). For these reasons even optically correct goggles will always "bend" light and the degree to which this happens will vary greatly from rider to rider.
Polycarbonate is used by the major brands as the lens material. There are many trade names used for Polycarbonate. It is a great material in that it is very impact resistant and heat resistant and it has terrific optical properties. On the downside it scratches very easily. Multiple coatings and finishes are also used on snowboard goggles. Anything applied to the Polycarbonate lens impacts optical quality. Multi million dollar machines are used to apply these coatings. The plating machinery that is used to apply the "mirrored" multi color fade finishes is straight out of sci fi. The control required to apply these materials in depths that need to be even, attractive and varied in color is mind blowing. The depth of these finishes is measured in microns (millionths of a meter). Again, that sounds rad and it is...but...in every instance these finishes are very scratch sensitive. That refers to both the plating and the fog proofing. I mention this because even though the initial coatings are robotically applied at amazing tolerances, in the real world they can be degraded far more easily than I would like. This directly impacts optical quality. So on one hand we have these awesome materials that were developed in large by NASA for space visors and on the other hand we have a product that can be degraded by paper towel.
STOKED!
Optically Correct Snowboard Goggles - Lens Design Vs. Real world
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