U.S. patent application number 10/000062 was filed with the patent office on 2004-04-15 for waterman's sunglass lens.
Invention is credited to Ishak, Andrew.
Application Number | 20040070726 10/000062 |
Document ID | / |
Family ID | 32074179 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040070726 |
Kind Code |
A1 |
Ishak, Andrew |
April 15, 2004 |
Waterman's sunglass lens
Abstract
An improved ten-layer performance polarized lens for sunglasses.
The lens design maximizes the benefit to watermen, giving them a
combination of outer hydrophobic overcoat to protect the lens from
seawater and smudging, multi-layer dielectric mirror which further
reduces glare and overall light transmission, two layers of
high-contrast blue-blocking amber or color-discriminating grey
ophthalmic CR-39 plastic or polycarbonate, sandwiching a polarizing
layer. The foregoing layers are arranged to provide a balanced
light transmission profile optimum for use on the water in which
100% of UV-A & B light is absorbed to at least 400 nm. An
alternative embodiment is described in which a Rugate filter is
incorporated in place of or in addition to the multi-layer
dielectric mirror. The resulting watermens' dielectric-mirrored
sunglass lens reduces both overall light transmission and ocular
photochemical damage, and is available in either high-contrast
blue-light blocking amber or grey coloration.
Inventors: |
Ishak, Andrew; (Havre de
Grace, MD) |
Correspondence
Address: |
ROYAL W. CRAIG
LAW OFFICES OF ROYAL W. CRAIG
10 NORTH CALVERT STREET
SUITE 153
BALTIMORE
MD
21202
US
|
Family ID: |
32074179 |
Appl. No.: |
10/000062 |
Filed: |
November 2, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60245304 |
Nov 3, 2000 |
|
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60266497 |
Feb 5, 2001 |
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Current U.S.
Class: |
351/159.27 |
Current CPC
Class: |
G02C 2202/16 20130101;
G02C 7/12 20130101; G02C 7/10 20130101 |
Class at
Publication: |
351/163 ;
351/165 |
International
Class: |
G02C 007/10 |
Claims
I claim:
1. A sunglass lens, comprising: a dielectric mirror for reducing
glare and overall light transmission; a first layer ophthalmic
plastic; a second layer ophthalmic plastic; a polarizing layer
encapsulated between said first and second plastic layers; whereby
said layers are arranged to provide a balanced light transmission
profile in which substantially 100% of UV-A & B light is
absorbed to at least 400 nm.
2. The sunglass lens according to claim 1, wherein said first and
second ophthalmic plastic layers are colorized with one from among
the group of high-contrast blue-blocking amber-tint and color
discriminating grey tint.
3. The sunglass lens according to claim 2, wherein said first and
second layers are CR-39 plastic.
4. The sunglass lens according to claim 3, wherein said first and
second layers are polycarbonate.
5. The sunglass lens according to claim 1, wherein said dielectric
mirror further comprises a multi-layered dielectric mirror.
6. The sunglass lens according to claim 5, wherein said
multi-layered dielectric mirror further comprises at least six thin
film layers vacuum deposited atop said first layer of plastic for
further reducing light transmission and glare.
7. The sunglass lens according to claim 2, wherein said polarizing
filter layer is molecularly bonded between said first and second
ophthalmic plastic layers to avoid haze and delamination.
8. The sunglass lens according to claim 1, wherein said first and
second ophthalmic plastic layers are colorized with a color
discriminating grey tint, and the average blue light transmission
of said lens is less than 7%.
9. The sunglass lens according to claim 1, wherein said first and
second ophthalmic plastic layers are colorized with a high-contrast
blue-blocking amber-tint, and the average blue light transmission
of said lens is less than 0.4%.
10. A sunglass lens, comprising: a first layer hydrophobic overcoat
for protection from seawater and smudging; a second layer
dielectric mirror for further reducing light transmission and
glare; a third layer blue-blocking amber-tinted ophthalmic plastic
material; a fourth polarizing layer; a fifth layer blue-blocking
amber-tinted ophthalmic plastic material; whereby said layers are
arranged to provide a balanced light transmission profile optimum
for use on the water in which substantially 100% of UV-A & B
light is absorbed and with at least 99% absorption of blue light at
up to 490 nm.
11. The sunglass lens according to claim 10, wherein said
dielectric mirror further comprises a multi-layered dielectric
mirror.
12. The sunglass lens according to claim 11, wherein said
multi-layered dielectric mirror further comprises at least six thin
film layers vacuum deposited atop said first layer of ophthalmic
plastic for further reducing light transmission and glare.
13. The sunglass lens according to claim 12, wherein said
polarizing filter layer is molecularly bonded between said first
and second ophthalmic plastic layers to avoid haze and
delamination.
14. The sunglass lens according to claim 13, wherein said said
first and second ophthalmic plastic layers are CR-39 plastic.
15. The sunglass lens according to claim 14, wherein said first and
second ophthalmic layers are polycarbonate.
16. The sunglass lens according to claim 14, wherein said first and
second ophthalmic plastic layers are colorized with a high-contrast
blue-blocking amber-tint, and the average blue light transmission
of said lens is less than 0.4%.
17. A sunglass lens, comprising: a first layer hydrophobic overcoat
for protection from seawater and smudging; a second layer
dielectric mirror for further reducing light transmission and
enhancing UV obstruction; a third layer color-discriminating
grey-tinted ophthalmic CR-39 plastic; a fourth polarizing layer; a
fifth layer color-discriminating grey-tinted ophthalmic CR-39
plastic; whereby said layers are arranged to provide a balanced
light transmission profile optimum for use on the water in which
substantially 100% of UV-A & B light is absorbed and with at
least 99% absorption of blue light at up to 410 nm.
18. The sunglass lens according to claim 17, wherein said first and
second layers are CR-39 plastic.
19. The sunglass lens according to claim 17, wherein said first and
second layers are polycarbonate.
20. The sunglass lens according to claim 17, wherein said
dielectric mirror further comprises a multi-layered dielectric
mirror.
21. The sunglass lens according to claim 20, wherein said
multi-layered dielectric mirror further comprises at least six thin
film layers vacuum deposited atop said first layer for further
reducing light transmission and glare.
22. The sunglass lens according to claim 21, wherein said
polarizing filter layer is molecularly bonded between said first
and second CR-39 lenses to avoid haze and delamination.
23. The sunglass lens according to claim 20, wherein said first and
second ophthalmic plastic layers are colorized with a color
discriminating grey tint, and the average blue light transmission
of said lens is less than 7%.
24. A sunglass lens comprising a rugate filter formed as a
transparent coating with an incrementally varying refractive index
profile along its width arranged to provide a balanced light
transmission profile in which substantially 100% of UV-A & B
light is absorbed to at least 400 nm.
25. The sunglass lens according to claim 24, wherein said rugate
filter is encapsulated between a first lens layer and a second lens
layer.
26. The sunglass lens according to claim 25, wherein said first
lens layer and second lens layer are ophthalmic plastic.
27. The sunglass lens according to claim 25, wherein said first
lens layer and second lens layers are glass.
28. The sunglass lens according to claim 25, further comprising a
dielectric mirror for reducing glare and overall light
transmission.
29. The sunglass lens according to claim 26, wherein said first and
second ophthalmic plastic layers are colorized with one from among
the group of high-contrast blue-blocking amber-tint and color
discriminating grey tint.
30. The sunglass lens according to claim 26, wherein said first and
second layers are CR-39 plastic.
31. The sunglass lens according to claim 26, wherein said first and
second layers are polycarbonate.
32. The sunglass lens according to claim 28, wherein said
dielectric mirror further comprises a multi-layered dielectric
mirror.
33. The sunglass lens according to claim 32, wherein said
multi-layered dielectric mirror further comprises at least six thin
film layers vacuum deposited atop said first layer of plastic for
further reducing light transmission and glare.
34. The sunglass lens according to claim 29, wherein said first and
second ophthalmic plastic layers are colorized with a color
discriminating grey tint, and the average blue light transmission
of said lens is less than 7%.
35. The sunglass lens according to claim 29, wherein said first and
second ophthalmic plastic layers are colorized with a high-contrast
blue-blocking amber-tint, and the average blue light transmission
of said lens is less than 0.4%.
36. A sunglass lens comprising rugate filter means for selectively
filtering wavelengths of light to preserve macular integrity.
37. A sunglass lens, comprising: a rugate filter formed as a
transparent coating with an incrementally varying refractive index
profile along its width; a polarizing layer; said rugate filter and
polarizing layer being encapsulated between first and second
plastic layers; whereby said polarizing layer, rugate filter, and
first and second plastic layers are arranged to provide a balanced
light transmission profile in which substantially 100% of UV-A
& B light is absorbed to at least 400 nm.
38. The sunglass lens according to claim 37, wherein said first
lens layer and second lens layer are ophthalmic plastic.
39. The sunglass lens according to claim 39, further comprising a
dielectric mirror for reducing glare and overall light
transmission.
40. The sunglass lens according to claim 38, wherein said first and
second ophthalmic plastic layers are colorized with one from among
the group of high-contrast blue-blocking amber-tint and color
discriminating grey tint.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application derives priority from U.S.
Provisional Patent Applications Nos. 60/245,304 and 60/266,497,
both for "WATERMAN'S SUNGLASS LENS", filed: Nov. 3, 2000 and Feb.
5, 2001, respectively.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to sunglasses and, more
particularly, to an improved multi-layer lightweight CR-39,
polarized, dielectric-mirrored sunglass lens specifically designed
for watermen, to reduce both overall light transmission and ocular
photochemical damage, available in either high-contrast blue-light
blocking amber or grey coloration.
[0004] 2. Description of the Background
[0005] Quality polarized sunglasses have evolved to the point where
they often incorporate numerous layers and coatings all of which
combine to provide a particular light transmission profile. The
efficacy of each layer affects that of each subsequent layer, and a
good design effort often involves the balancing of numerous optical
constraints in pursuit of a synergistic result. The most useful
balance for outdoor enthusiasts such as watermen is a lens having a
patterned absorption profile over a broad spectral range. More
specifically, the lens should absorb higher energy light more
strongly than lower energy light, e.g., more UV light than blue,
more blue than green, etc.
[0006] Ultraviolet radiation falls within a range of wavelengths
below visible light, generally between 100 and 400 nanometers. Long
UVA radiation occurs at wavelengths between 315 and 400 nanometers.
UVB radiation occurs between 280 and 315 nanometers. UVC radiation
occurs between 200 and 280 nanometers. Wavelengths between 100 and
200 nanometers are known as vacuum UV. Vacuum UV and UVC are the
most harmful to humans, but the earth's ozone layer tends to block
these types of ultraviolet radiation. Nevertheless, the occurrence
of ocular injury from ultraviolet exposure has increased
dramatically over the past few years, and this is thought to be a
result of ozone layer depletion. Given current efforts to restore
the ozone layer, it is optimistically predicted to reach original
levels by the year 2050. Others speculate that the developing black
markets for ozone-depleting agents such as CFC refrigerant will add
further delay. Bergmanson et al., Practicing Preventative Eye Care
With UV-Blocking Eye Wear, Contact Lens Spectrum (February
1998).
[0007] According to Prevent Blindness America, the American Academy
of Ophthalmology, and the American Optometric Association,
"Ultraviolet radiation can play a contributory role in the
development of various eye disorders including age-related
cataract, pterygium (growth of tissue from the white of the eye
onto the cornea), cancer of the skin around the eye, photokeratitis
(sunburn of the cornea) and corneal degeneration." Cataracts are a
major cause of visual impairment and blindness worldwide. "We've
found there is no safe dose of UV-B exposure when it comes to risk
of cataract, which means people of all ages, races and both sexes
should protect their eyes from sunlight year-round." Infeld, Karen,
Sunlight Poses Universal Cataract Risk, Johns Hopkins Study,
http://www.eurekalert.org/releases/jhu-sunposcat.html (1998).
[0008] Age-related macular degeneration (AMD) is the leading cause
of blind registration in the western world, and its prevalence is
likely to rise as a consequence of increasing longevity. Beatty et
al., The Role of Oxidative Stress in the Pathogenesis of
Age-Related Macular Degeneration, Survey of Ophthalmology, volume
45, no. 2 (Sept-Oct 2000). Macular pigment is also believed to
limit retinal oxidative damage by absorbing incoming blue light
and/or quenching reactive oxygen intermediates. Many putative risk
factors for AMD have been linked to the lack of macular pigment,
including female gender, lens density, tobacco use, light iris
color, and reduced visual sensitivity. The absorbency spectrum of
macular pigment peaks at 460 nm (Id at 165), and it has been
calculated that carotenoids reduce the amount of blue light
incident on the photoreceptors of the fovea by approximately
40%.
[0009] The incidence of visible blue light exposure is a
contributing cause of AMD. Photochemical retinal injury in monkeys
from visible blue light (441 nm) was shown by Ham et al.,
"Histologic Analysis of Photochemical Lesions Produced in Rhesus
Retina by Short-wave-length Light", Invest Ophthalmol Vis Sci
17:1029-35 (1978). It was found that short-wavelength light
resulted in damage to the photoreceptor outer segments, cellular
proliferation, and other symptoms which resembled changes seen in
AMD. It was reported that the power required to cause such damage
was 70 to 1000 times lower for blue light (441.6 nm) than for
infrared wavelengths (1064 nm) based on exposure times ranging from
1 to 100 seconds. This was confirmed by Wu et al. who confirmed
that the mechanism of blue light induced cell death is apoptosis.
Wu J et al., "Blue Light Induced Apoptosis in Rat Retina", Eye
13:577-83 (1999).
[0010] As the entire population is potentially exposed to sunlight,
the odds ratio of 13.6 and 2.19 for high exposure to visible blue
light and AMD represent quite robust evidence in support of the
sunlight/AMD hypothesis. Consequently, a sunlens that dramatically
reduces visible blue light combined with a high degree of UVA and
UVB protection will preserve visual function.
[0011] The Food and Drug Administration recommends that all
sunglasses, prescription or non-prescription, block 99% of UVB and
95% of UVA. Most sunglasses on the market meet these criteria.
Indeed, there are sunglasses for outdoor enthusiasts that can
achieve 99% of both UVA & B obstruction.
[0012] In addition to simply blocking harmful light, a quality lens
will also strive to reduce glare, add contrast, and yet maintain
color balance all to enhance vision. All this requires a lens with
an optimum transmission profile that filters the different colors
in proportion to their ability to damage the tissue of the retina,
thereby reducing the risks of macular degeneration while actually
improving vision. Presently, a number of advancements in lens
technology give significant control over the transmission profile
of lenses.
[0013] Polarization
[0014] It is common to provide polarized lenses in sunglasses to
eliminate the horizontal transmission of reflected light through
the lenses of the glasses to the eyes of the wearer. The polarizing
layer blocks light at certain angles, while allowing light to
transmit through select angles. This helps to negate annoying glare
reflected off other surfaces such as water, snow, automobile
windshields, etc. A polarized filter is produced by stretching a
thin sheet of polyvinyl alcohol to align the molecular components
in parallel rows. The material is passed through an iodine
solution, and the iodine molecules likewise align themselves along
the rows of polyvinyl alcohol. The sheet of polyvinyl is then
applied to the lens with colored rows of iodine oriented vertically
in order to eliminate horizontally reflected light. The sheet of
polyvinyl may be applied to a lens in one of two ways: the
lamination method or the cast-in mold method. To polarize a glass
lens, the lamination method is used whereby the polyvinyl filter is
sandwiched between two layers of glass. For plastic lenses, the
cast-in mold method is used whereby the polyvinyl filter is placed
within the lens mold. Relevant prior art patents might be seen in
the Schwartz U.S. Pat. No. 3,838,913 and Archambault U.S. Pat. No.
2,813,459. A significant benefit of polarized lenses is the
elimination of glare from reflective surfaces such as water.
[0015] Color Filters
[0016] Color filters can also provide excellent ultraviolet
obstruction properties. For example, U.S. Pat. No. 4,952,046
(SunTiger) discloses an optical lens with an amber filter having
selective transmissivity functions. This is the original
"Blue-blocker" patent for amber lenses that substantially
eliminates ultraviolet radiation shorter than 515 nm. The lens is
substantially transparent to wavelengths greater than 636 nm which
are most useful for high visual acuity in a bright sunlit
environment. Similarly, U.S. Pat. No. 5,400,175 (SunTiger)
discloses an amber filter having a cut-on at 550 nm. However,
color-differentiation is highly distorted due to the deep orange
tint.
[0017] Similarly, PhotoProtective Technologies of San Antonio, Tex.
produces lenses having Melanin pigment. These are said to eliminate
all the UV (thereby reducing the risks of cataracts); reduce the
violet and blue light (to reduce the risks of macular
degeneration); and reduce glare.
[0018] The value of color filtration is further apparent in U.S.
Pat. No. 6,145,984 to Farwig, which discloses a color-enhancing
polarized lens with a trichroic contrast enhancer that yields a
virtually colorless gray to the eye, and yet improves the areas of
color saturation, chromatic and luminous contrast, clarity of
detail, depth perception, and haze penetration.
[0019] It would be medically valuable to provide a lens that
likewise eliminates all the UV light, and also reduces visible blue
light to its lowest possible level.
[0020] Mirror Coatings
[0021] Various mirror coatings have been available to the sunglass
industry for decades. These mirror coatings can be applied to the
front and/or back surface of a lens to further reduce glare and
provide protection against infrared rays. Metallic mirrors comprise
a layer of metal deposited directly on a glass lens to create the
equivalent of a one-way mirror. U.S. Pat. No. 4,070,097 to Gelber,
Robert M (1978). However, most metallic oxide coatings have proven
to be very susceptible to scratching and wear, especially near salt
water. Salt water tends to degrade such coatings over time. In
addition, metallic mirror coatings absorb light and generate heat.
The more recent advent of dielectric mirror coatings solve some of
the above-referenced problems. For one, dielectric coatings reflect
light without absorption, thereby avoiding the discomfort of hot
glasses. Moreover, dielectric coatings are more durable than
metallic oxide coatings, especially in outdoor coastal
environments. For example, a dielectric layer having a medium
refractive index, e.g., a mixed TiO2 and SiO2 layer, has been used
in a rear view mirror. U.S. Pat. No. 5,267,081 to Pein (1993).
Similar titanium and quartz dielectric mirror coatings have been
applied to glass lenses. In the context of sunglasses, these
dielectric mirror coatings of titanium and quartz prevent salt
water damage while providing additional reflection of light.
[0022] U.S. Pat. No. 6,077,569 and U.S. Pat. No. 5,846,649 to Knapp
et al. suggest a plastic sunglass lens coated with an abrasion
resistant material and a dielectric material (including silicon
dioxide or titanium oxide). The abrasion-resistant coating layer
includes a transparent adhesion layer comprised of C, Si, H, O,
and/or N which is deposited by ion-assisted plasma deposition. A
second dielectric coating layer is deposited, and a thin metallic
mirror layer may be interposed between the abrasion-resistant layer
and the dielectric materials to enhance reflectivity and color
characteristics. However, the prior art does not teach or suggest
how to incorporate a polarizing filter, multi-layer dielectric
mirror, and a hydrophobic overcoat in a blue-blocking amber or gray
tint lens to provide an outstanding spectroscopic profile,
especially for a marine environment.
[0023] Hydrophobic Coatings
[0024] Hydrophobic coatings are known in a more general context for
protecting lens surfaces (U.S. Pat. No. 5,417,744 to Ameron) and
for contact lenses (U.S. Pat. No. 4,569,858 to Barnes Hind).
Hydrophobic coatings are also appropriate near water to protect
underlying layers of a lens over time. Hydrophobic coatings are
especially good for protecting mirrored lenses as above. For
example, U.S. Pat. No. 5,928,718 to Dillon discloses a protective
coating for reflective sunglasses incorporating a conventional
resin/polymer type coating for protection of the mirror finish
against abrasion and smudging.
[0025] Rugate Filters
[0026] As an alternative or as a supplement to be used in
combination with the above, a Rugate filter is an interference
coating in which the refractive index varies continuously in the
direction perpendicular to the film plane. The addition of a rugate
filter to a lens can block visible blue and UV light, as well as
infrared and laser energy, while allowing other visible light to
pass unimpeded. Rugate filters are wavelength specific filters that
have existed for about a decade. Their simple periodic continuous
structures offer a much wider set of spectral responses than
discrete structures, and they typically exhibit a spectrum with
high reflectivity bands. This allows the possibility of making high
reflectivity mirrors with very narrow bandwidth. As an example,
Rugate notch filters from Barr Associates use refractory metal
oxides for edge filters and beamsplitters. Rugate filters are
typically formed by a continuous deposition process, it is an easy
matter to vary the mixture deposited on the substrate, and thus
vary the index of refraction. An overview of Rugate filter
technology can be found at Johnson et al., "Introduction to Rugate
Filter Technology" SPIE Vol. 2046, p. 88-108 (November 1993),
inclusive of how a simple rugate filter is derived from Fourier
analysis. This article shows the utility of refractive index
profile tailoring and the advantages of using this technology.
Other examples can be found in U.S. Pat. No. 5,258,872 "Optical
Filter" by W. E. Johnson, et al. and disclosed in U.S. Pat. No.
5,475,531 "Broadband Rugate Filter" by T. D. Rahminow, et al.
Unfortunately it is difficult to manufacture rugate filters as they
require expensive vacuum deposition techniques called "sputtering."
In the sputtering process it is difficult to accurately control the
sputtering of two materials to precisely vary the index of
refraction. Other processes such as laser flash evaporation, ion
beam assisted deposition, resistive and electron-beam evaporation
do not lend themselves to plastic eyeglass lenses and/or require
relatively expensive equipment.
[0027] It would be greatly advantageous to provide a synergistic
combination of UV-absorbing light-weight CR-39, polarization, and
dielectric mirror technology in such a way as to maximize the
benefit to watermen. Specifically, it would be advantageous to
provide a combination of: a) outer hydrophobic overcoat to protect
the lens from seawater and smudging; b) multi-layer dielectric
mirror which further reduces light-transmission and glare; and c)
two layers of high-contrast ophthalmic CR-39 (plastic) having
either a blue-blocking amber-tint or color-discriminating grey
tint, d) the layers of CR-39 sandwiching; a cast-in mold polarizing
layer, and arranged to provide an unsurpassed light transmission
profile optimum for use on the water in which there is 100%
absorption of UVA & B light. It would also be advantageous to
provide a Rugate filter in place of or as a supplement to the
foregoing dielectric mirror to even further reduce the visible blue
light as well as infrared and laser energy.
SUMMARY OF THE INVENTION
[0028] It is an object of the present invention to provide a
sunglass lens specially adapted for use by watermen which adheres a
multi-layer dielectric mirror to two layers of ophthalmic CR-39
(plastic) and/or impact resistant polycarbonate sandwiching a
polarizing filter. This combination reduces both glare and overall
light transmission.
[0029] It is another object to incorporate the multi-layer
dielectric mirror with a CR-39 (plastic) and/or impact resistant
polycarbonate lens to further decrease the transmission values of
the tinted lens and yet provide outstanding durability
characteristics.
[0030] It is another object to provide a lens as described above
which incorporates the polarizing filter between two-layers of
high-contrast blue-blocking amber-tinted ophthalmic CR-39 (plastic)
and/or impact resistant polycarbonate to absorb 100% of ultraviolet
light and reduce visible blue light transmission to less than
0.5%.
[0031] It is another object to provide a lens as described above
which incorporates the polarizing filter between two-layers of
color-discriminating grey ophthalmic CR-39 (plastic) and/or impact
resistant polycarbonate to absorb 100% of ultraviolet light and
reduce visible blue light transmission to less than 7%.
[0032] It is another object to provide a lens as described above
that additionally includes an outer hydrophobic overcoat to protect
the inner lens layers from seawater and smudging.
[0033] It is another object to provide a lens that incorporates a
Rugate filter in place of or as a supplement to the foregoing
dielectric mirror to even further reduce the visible blue light as
well as infrared and laser energy.
[0034] According to the present invention, the above-described and
other objects are accomplished by providing an improved ten-layer
light-weight CR-39 or impact resistant polycarbonate, polarized,
dielectric-mirrored lens for sunglasses. The lens includes an outer
hydrophobic overcoat to protect the inner lens layers from seawater
and smudging. Next is a six-layer dielectric mirror which further
reduces light transmission. The mirror is bonded to two layers of
CR-39 (plastic) or impact resistant polycarbonate, in either amber
or grey tint, the foregoing layers sandwiching a polarizing filter
for a total of ten layers.
[0035] As an option (or as a substitute for the dielectric mirror),
the lens may incorporate a Rugate filter.
[0036] Superior test results for the above-described lenses (for
performance, function and durability) distinguish them from
existing lenses and evidence the synergistic relationship of the
particular combination of layers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Other objects, features, and advantages of the present
invention will become more apparent from the following detailed
description of the preferred embodiment and certain modifications
thereof when taken together with the accompanying drawings in
which:
[0038] FIG. 1 is a perspective exploded sketch showing the various
lens layers according to the present invention.
[0039] FIG. 2 is a spectral analysis showing the light transmission
profile of the improved multi-layer grey sunglass lens for watermen
according to the present invention (analysis by Colts Laboratories
of Clearwater Fla., a leading and accredited analysis
laboratory).
[0040] FIG. 2A is a definition analysis showing the definition
profile of the improved multi-layer grey sunglass lens for watermen
according to the present invention.
[0041] FIG. 3 is a spectral analysis showing the light transmission
profile of the improved multi-layer grey sunglass lens as above
without the dielectric mirror or hydrophobic coating (Colt
Labs).
[0042] FIG. 4 is a spectral analysis showing the light transmission
profile of the improved multi-layer amber sunglass lens for
watermen according to the present invention (Colts Labs).
[0043] FIG. 4A is a definition analysis showing the definition
profile of the improved multi-layer amber sunglass lens for
watermen according to the present invention.
[0044] FIG. 5 is a spectral analysis showing the light transmission
profile of the improved multi-layer amber sunglass lens as above
without the dielectric mirror or hydrophobic coating (Colts
Labs).
[0045] FIG. 6 is a spectral analysis for comparative purposes
showing the light transmission profile of competing Ray Ban.RTM.
sunglass lens (Colts Labs).
[0046] FIG. 7 is a spectral analysis for comparative purposes
showing the light transmission profile of competing BluBlocker.RTM.
sunglass lens (Colts Labs).
[0047] FIG. 8 is a spectral analysis for comparative purposes
showing the light transmission profile of competing Costa Del
Mar.RTM. sunglass lens (Colts Labs).
[0048] FIG. 9 is a spectral analysis for comparative purposes
showing the light transmission profile of competing Melavision.RTM.
(Photoprotective Technologies) sunglass lens (Colts Labs).
[0049] FIG. 10 is a perspective exploded sketch showing the various
lens layers according to another embodiment of the present
invention in which a Rugate filter 50 is incorporated in place of
the multi-layered dielectric mirror layer 14 of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] Disclosed is an improved ten-layer lightweight CR-39
(plastic) polarized, dielectric mirrored sunglass that gives a
light transmission profile in which 100% of UVA & B light
absorption occurs in high contrast blue-blocking amber and
color-discriminating grey. Either embodiment is optimum for use on
the water.
[0051] FIG. 1 is a perspective exploded sketch showing the various
lens layers according to the present invention. The outermost layer
13 of lens 2 is a hydrophobic overcoat. The hydrophobic coating is
preferably a silicon-based chemical coating of known type such as
commercially available from OMS, 177108 Canada Inc., 5120 Courtrai,
Suite 12, Montreal, Quebec, Canada H3W 1A7. This coating 13 may be
deposited by known dipping or chemical vapor deposition processes,
and it makes the lens water repellant for better vision during
rainstorms or water related activities. In addition, hydrophobic
overcoat 13 makes the lens easier to clean as contaminants do not
adhere to the lubricated lens surface easily. Moreover, the
hydrophobic overcoat 13 resists smudging and streaking due to
environmental and body contaminants. This hydrophobic layer 13 also
produces a sealing effect to protect the lens and other base
coatings, and to increases the longevity of the underlying layers.
The hydrophobic coating 13 bonds with the lens to create a barrier
against dirt, repelling dust, grease and liquid. The coating is
non-acidic. It allows the lens to be cleaned with a wiping cloth
without cleaning solution. The hydrophobic coating does not
optically change the lens properties. It is extremely durable water
repellant and not only repels water, but any other undesirable
matter, including salt spray. The hydrophobic coating also combats
bacterial build-up as dirt and oils do not stay on the lens.
[0052] The hydrophobic overcoat 13 is applied directly onto a
multi-layered dielectric mirror layer 14. U.S. Pat. No. 5,844,225
to Kimock et al discloses an optical coating design formed in a
multi-layer "dielectric stack" configuration for producing an
anti-reflection feature, plus a method for fabricating a coated
substrate product. Kimock et al. '225 also suggests various stacked
layers inclusive of titanium oxide, nitride, zirconium nitride,
boron nitride, yttrium oxide, silicon oxide, silicon dioxide,
zirconium oxide, silicon carbide, aluminum oxide, aluminum nitride,
and various mixtures thereof. The present invention employs a
similar method to create a particular stacked layer 14 which
actually comprises six equal-thickness thin film layers (2-3 nm
total) of titanium oxide, silicon dioxide (quartz), zirconium
oxide, and chromium, each thin film layer being vacuum deposited
separately in alternating 90 degree angles to provide a reflective
mirror finish. Dielectric mirrors in general combine high
reflection values with outstanding durability characteristics.
These coatings can generally exhibit significantly higher
reflectance values than metallic films over specific wavelength
intervals. The present stacked dielectric mirror layer 14 with
particular constituents applied in alternating angular deposits
further optimizes the lens to reduce light transmission through the
entire UV and visible light spectrum.
[0053] The next three lens layers 16-18 include a polarizing filter
layer 17 bonded between two lightweight CR-39 (plastic) or
polycarbonate layers 16, 18.
[0054] In one embodiment, high-contrast blue-blocking amber CR-39
(plastic) or polycarbonate layers 16, 18 are specifically chosen
for their dramatic glare blocking properties which in combination
with the dielectric mirror 14 yield the excellent light
transmission profile of the present invention.
[0055] In an alternate embodiment, ophthalmic grey CR-39 (plastic)
or polycarbonate layers 16, 18 are specifically chosen for their
superior color-discriminating capability.
[0056] Either CR-39 (plastic) or polycarbonate lens blanks may be
used as both types of materials are capable of molecular bonding,
which is important for the following reasons.
[0057] For the polarizing filter layer 17, there are basically two
types of polarized lens constructions, laminated and cast suspended
filter. Laminated lenses are made by sandwiching the polarized film
between layers of plastic or glass, utilizing an adhesive to hold
it together. The adhesive can make the laminated lens appear hazy
and the adhesion can fail when subjected to high heat and
processing forces. The CR-39 polarized lens 16 of the present
invention is cast with suspended filter and does not rely upon
adhesives to hold everything together. Molecular bonding is used to
chemically join the lens layers 16-18, thus totally encapsulating
the polarizing filter layer 17 between the two CR-39 plastic lens
layers 16, 18, thereby avoiding haze and delamination.
[0058] The combination of the above-described hydrophobic layer 13,
dielectric mirror layer 14, and polarizing lens layers 16-18
dramatically reduce glare and increase contrast in varying types of
light conditions, and the bonded configuration is most durable for
use in a marine environment.
[0059] FIG. 2 is a spectral analysis (with data print attached)
showing the light transmission profile of the improved multi-layer
grey sunglass lens for watermen according to the present invention.
The attached spectral analysis was conducted by Colts Laboratories
of Clearwater Fla., a leading analysis laboratory that is
accredited by the American Association for Laboratory Accreditation
to ISO Guide 25 and by the Safety Equipment Institute. It can
readily be seen that the light transmission properties of the
improved multi-layer sunglass lens are optimized for watermen.
Ultraviolet absorption of 100% of UV-A & B light occurs to at
least 400 nm, average blue light transmission is 6.84%, and these
profiles are optimum for use on the water.
[0060] FIG. 2A is a definition analysis showing the definition
profile of the improved multi-layer grey sunglass lens for watermen
according to the present invention.
[0061] The definition analysis is an ANSI standard test for eye and
face protective devices and rates the protectiveness of the lens in
terms of angular protection and frontal protection. It is
noteworthy that this particular ANSI Z87.1 specification is
important to waterman because of the rough environment they work
in. The ability of the present lens to surpass this impact standard
is a salient feature.
[0062] FIG. 3 is a spectral analysis (with data print attached)
showing the light transmission profile of the improved multi-layer
grey sunglass lens as above without the dielectric mirror or
hydrophobic coating. It can be seen by comparing FIGS. 2 and 3 that
the dielectric mirror layer 14 reduces light transmission by as
much as an additional 3-4% percent in the 420-500 nm range (note
that there is no increase in UV absorption as with metallic mirror
coatings, but only a reduction in transmitted light). The use of a
dielectric mirror 14 rather than metallic provides improved glare
screening, scratch resistance and overall durability, and it does
not absorb light or generate heat. This is ideal for performance
water activities, especially in extremely bright daylight
conditions.
[0063] FIG. 4 is a spectral analysis (with data print attached)
showing the light transmission profile of the improved multi-layer
amber sunglass lens for watermen according to the present
invention. Ultraviolet absorption of 100% occurs to at least 400
nm, average blue light transmission is an unprecedented 0.34%, and
these profiles are optimum for use on the water.
[0064] FIG. 4A is a definition analysis (similar to FIG. 2A)
showing the definition profile of the improved multi-layer amber
sunglass lens for watermen according to the present invention.
[0065] FIG. 5 is a spectral analysis (with data print attached)
showing the light transmission profile of the improved multi-layer
amber sunglass lens as above without the dielectric mirror or
hydrophobic coating. As before, it can be seen by comparing FIGS. 4
and 5 that the dielectric mirror layer 14 reduces light
transmission by an additional 1-3 percent in the 500-600 nm range
(again there is no increase in UV absorption as with metallic
mirror coatings, but only a reduction in transmitted light). The
same additional benefits of improved glare screening, scratch
resistance and overall durability are gained.
[0066] FIGS. 6-9 are comparative test results with a few exemplary
existing lenses.
[0067] Specifically, FIGS. 6-9 are spectral analyses for
comparative purposes showing the light transmission profile of a
competing Ray Ban.RTM. sunglass lens, BluBlocker.RTM. sunglass
lens, Costa Del Mar.RTM. sunglass lens, and Melavision.RTM.
sunglass lens, respectively. Comparison with the results for the
present lenses as shown in FIGS. 2 and 4 reveals a significant
inability on the part of the competitors with regard to average
blue light obstruction.
[0068] The average blue light filtering ability (% transmission)
for the present lenses as compared to the test results of FIGS. 6-9
are as follows:
1 Average Blue Light Transmission Subject Lens (Lower is better)
Multi-layer amber lens of the present 0.34% (FIG. 4) invention
BluBlocker .RTM. sunglass lens 0.85% (FIG. 7) Costa Del Mar .RTM.
sunglass lens 2.58% (FIG. 8) Ray Ban .RTM. sunglass lens 4.90%
(FIG. 6) Multi-layer grey lens of the present 6.84% (FIG. 2)
invention Melavision .RTM. sunglass lens 6.93% (FIG. 9)
[0069] Comparing these results shows a much greater ability on the
part of the present amber lens to filter blue light while also
reducing glare, adding contrast, and maintaining color balance.
Only the BluBlocker lenses approach the same level of
effectiveness, however, color discrimination is markedly reduced
because of the blu-blocking deep orange coloration. The others
increase the risk of photochemical retinal damage as described
earlier. Therefore, the present invention outperforms all others
with regard to preserving ocular physiological integrity (UV-A
& B light is absorbed to higher wavelengths, and more visible
blue light is filtered), and yet a balanced light transmission
profile is maintained for better visual acuity.
[0070] The present invention also contemplates the use of a Rugate
filter in place of or as a supplement to the foregoing dielectric
mirror to even further reduce the visible blue light as well as
infrared and laser energy. While more expensive to produce, Rugate
filters are effective bandpass filters that can be made to exhibit
the same light transmission profile. Referring to FIG. 10, a Rugate
filter 50 may be incorporated in place of the multi-layered
dielectric mirror layer 14 of FIG. 1. Alternatively, the Rugate
filter may be deposited directly on the multi-layered dielectric
mirror layer 14 as a supplement thereto. The Rugate coating 50 may
be a combination of Silicon, Oxygen and Nitrogen compounds in
specific ratios providing a pre-defined variation in the index of
refraction. For example, Silicon Dioxide (SiO.sub.2) provides an
index of refraction of about 1.5 while Silicon Nitride (Si.sub.3
N.sub.4) provides a value of about 2.0. For present purposes, the
variation in the index of refraction is calculated in order to
complement or supplement the above-described dielectric mirror,
e.g., by further reducing the visible blue light as well as
infrared and laser energy. It should be noted that other
combinations can be used to achieve this desired light transmission
profile. For example, tantala/silica and hafnia/silica combinations
have been used for multilayer coatings in the UV-A and UV-B
spectral range, and layers of silica and alumina have been used in
the UV-B and UV-C region. These materials are deposited by means of
a plasma-enhanced chemical vapor deposition process (PECVD) varying
the flow rate of Ammonia gas (NH.sub.3) and Nitrous Oxide gas
(NO.sub.2) in the presence of a mixture of Silane gas (SiH.sub.4)
and Argon, though it should be understood that other combination of
materials can be used. See, for example, Goetzelmann et al., "Uv
Coatings Produced with Plasma-ion-assisted Deposition", SPIE Vol.
3738, p. 48-57 (September 1999), which describes the
plasma-ion-assisted deposition for the production of multilayer
coatings for the visible and NIR spectral range including rugate
filters.
[0071] The Rugate filter is deposited on one of the lens layers
16-18 via plasma-enhanced chemical vapor deposition using a vacuum
chamber in which, for example, lens layer 16 is placed with the
rugate filter coating 50 deposited thereon by a traditional
evaporation method. The coating 50 is deposited on the lens layer
16 using an increment deposition approach, and this can be
implemented by computer control to achieve the desired sinusoidal
Rugate profile. Plasma-assist coating then relies on plasma to
bombard the thin Rugate film deposited by the traditional
evaporation method in order to improve the film's micro-structure.
In this type, the main chamber of a vacuum system is maintained at
a residual pressure around 10 mil by an inert, ionized sputter-gas
(for example, argon) called a plasma. An RF generator generates the
plasma within the chamber, and the flow of process gases are
controlled by a computer in a known manner. Plasma sputtering
generally needs a certain concentration of gas molecules, typically
1 to 10 millitorr of residual pressure, to operate. This results in
a single layer Rugate film 50 having a continuously varying index
of refraction along a thickness direction with a number of maxima
and minima in the index. The variation in the index of refraction
may be calculated in a known manner to provide a Rugate filter 50
in place of or as a supplement to the foregoing dielectric mirror
to further preserve visual integrity while also reducing glare,
adding contrast, and maintaining color balance. Preferably, the
Rugate filter used herein is color-neutral so as not to alter the
light transmission profile of the other lens layers. See, for
example, Johnson et al., "Color Neutral Rugate Filters", SPIE Vol.
2046, p. 132-140 (November 1993), which describes a transmissive
rugate filter which is designed to reflect a portion of the visible
spectrum and yet not appear to have a dominant color.
[0072] Having now fully set forth the preferred embodiment and
certain modifications of the concept underlying the present
invention, various other embodiments as well as certain variations
and modifications of the embodiments herein shown and described
will obviously occur to those skilled in the art upon becoming
familiar with said underlying concept. It is to be understood,
therefore, that the invention may be practiced otherwise than as
specifically set forth herein.
* * * * *
References