U.S. patent application number 13/495296 was filed with the patent office on 2013-06-20 for nano fractal diffuser.
The applicant listed for this patent is Mark Davis, Eric W. Gardner, Michael Lines. Invention is credited to Mark Davis, Eric W. Gardner, Michael Lines.
Application Number | 20130155516 13/495296 |
Document ID | / |
Family ID | 43380417 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130155516 |
Kind Code |
A1 |
Lines; Michael ; et
al. |
June 20, 2013 |
NANO FRACTAL DIFFUSER
Abstract
A diffusive device has an array of discrete facets which may be
of a size and pattern similar to a fractal. The facet dimensions
can be greater than half the wavelength of incident light such that
the facets substantially diffract light. A polarizing wire-grid
layer comprised of an array of elongated parallel conductive wires
with a period less than half the wavelength of incident light may
be disposed between, beneath, or above the facets. The wire-grid
polarizes the light by substantially reflecting light having an
s-polarization orientation and substantially transmitting a portion
of light having a p-polarization orientation.
Inventors: |
Lines; Michael; (Cedar
Hills, UT) ; Gardner; Eric W.; (Eagle Mountain,
UT) ; Davis; Mark; (Springville, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lines; Michael
Gardner; Eric W.
Davis; Mark |
Cedar Hills
Eagle Mountain
Springville |
UT
UT
UT |
US
US
US |
|
|
Family ID: |
43380417 |
Appl. No.: |
13/495296 |
Filed: |
June 13, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12491513 |
Jun 25, 2009 |
8248696 |
|
|
13495296 |
|
|
|
|
Current U.S.
Class: |
359/599 |
Current CPC
Class: |
G02B 5/0252 20130101;
G02B 5/3058 20130101; G02B 5/02 20130101; G02B 5/1814 20130101 |
Class at
Publication: |
359/599 |
International
Class: |
G02B 5/02 20060101
G02B005/02 |
Claims
1. A light diffuser comprising: a. a substrate having a top surface
and a bottom surface; b. a layer disposed over the top surface of
the substrate; and c. at least sixteen facets: i. having at least
two different sizes; ii. having a bottom surface disposed towards
the substrate and a top surface opposing the bottom surface; iii.
formed in the layer with facet dimensions >.lamda./2, where
.lamda. is the wavelength of light incident on the at least sixteen
facets to create a substantially diffuse light beam; and iv.
forming distinct groups arranged in a fractal pattern.
2. The light diffuser of claim 1, wherein the substrate and the
layer are formed of the same material.
3. The light diffuser of claim 1, wherein the substrate and the
layer comprise a different material.
4. The light diffuser of claim 1, wherein the facets are locations
that are cut into the layer.
5. The light diffuser of claim 1, wherein the at least sixteen
facets have at least two different thicknesses.
6. The light diffuser of claim 1, wherein the at least sixteen
facets have at least four different thicknesses.
7. The light diffuser of claim 1, wherein the at least sixteen
facets have square shapes.
8. The light diffuser of claim 1, wherein the facets are locations
that were masked during etching and are raised above surrounding
etched locations.
9. The light diffuser of claim 1, wherein the at least one layer
comprises at least two layers and the at least sixteen facets are
disposed over at least sixteen other facets.
10. The light diffuser of claim 9, wherein the at least two layers
are formed of the same material.
11. The light diffuser of claim 9, wherein the at least two layers
comprise a different material.
12. The light diffuser of claim 1, wherein the substrate comprises
a material that is opaque to the light such that substantially all
of the incoming light is diffusely reflected.
13. The light diffuser of claim 1, wherein the at least sixteen
facets have at least four different sizes.
14. The light diffuser of claim 1, wherein the facets are a solid
material surrounded by areas of the layer which have been
removed.
15. The light diffuser of claim 1, wherein the at least sixteen
facets comprise areas of the layer which have been removed, and are
surrounded by areas of the layer which have not been removed.
16. The light diffuser of claim 1, wherein a distance from the
bottom surface of the substrate to a top surface of at least one of
the at least sixteen facets is different than a distance from the
bottom surface of the substrate to a top surface of another of the
at least sixteen facets.
17. The light diffuser of claim 1, wherein areas of the top surface
of the substrate which is not covered with any of the at least
sixteen facets are covered by a wire grid and the wire grid
comprises a non polarizing material.
18. The light diffuser of claim 1, wherein the top surface of the
at least sixteen facets is covered with wire grid and the wire grid
comprises a non polarizing material.
19. A light diffuser comprising: a. a substrate having a top
surface and a bottom surface; b. at least one layer disposed over
the top surface of the substrate; and c. at least sixteen facets,
with a bottom surface disposed towards the substrate and a top
surface opposing the bottom surface, formed in one of the at least
one layer with facet dimensions >.lamda./2 where .lamda. is the
wavelength of light incident on the at least two facets to create a
substantially diffuse light beam.
20. A light diffuser comprising: a. a substrate having a top
surface and a bottom surface; b. a layer, disposed over the top
surface of the substrate, and formed of the same material as the
substrate; and c. at least sixteen facets: i. having at least four
different sizes with at least four different surface areas; ii.
having a bottom surface disposed towards the substrate and a top
surface opposing the bottom surface; iii. formed in the layer with
facet dimensions >.lamda./2, where .lamda. is the wavelength of
light incident on the at least sixteen facets; iv. forming distinct
groups arranged in a fractal pattern; and v. substantially
diffracting incident light.
Description
CLAIM OF PRIORITY
[0001] This is a continuation of U.S. patent application Ser. No.
12/491,513, filed on Jun. 25, 2009, which is hereby incorporated
herein by reference in its entirety.
RELATED APPLICATION(S)/PATENT(S)
[0002] This is related to U.S. Pat. Nos. 6,081,376; 6,348,995 and
7,630,133, which are hereby incorporated herein by reference in
their entirety.
BACKGROUND
[0003] 1. Field of the Invention
[0004] The present invention relates generally to optical diffusers
including diffusive wire-grid polarizers.
[0005] 2. Related Art
[0006] Wire-grid polarizers have been developed that are capable of
polarizing light, i.e. separating one polarization orientation from
another, by transmitting one polarization orientation and
reflecting the other. Wire grid polarizers are a periodic structure
of conductive elements with a length greater than the wavelength
and a period (p) less than half the wavelength of the incident
light, or p.ltoreq..lamda./2. Wire grid polarizers have been proven
to be effective for visible light (.about.300-700 nm, or
.about.0.3-0.7 microns or .mu.m) and their use demonstrated as
polarizers and beam splitters in optical imaging systems.
Typically, however, the reflection from, and the light passing
through, such wire-grid polarizers, is specular, or
mirror-like.
[0007] Wire-Grid polarizers are different from diffraction
gratings, which are a periodic structure of dielectric material
with a period (p) greater than half the wavelength (.lamda.) of
incident light, or p.gtoreq..lamda./2. The diffraction grating
scatters the incident light at discrete angles or directions in
accordance with m.lamda.=psin.theta., where m is the order and
.theta. is the angle with respect to normal from the diffraction
grating. Thus, different wavelengths are reflected or scattered at
different angles.
[0008] Various different types of wire-grid polarizers have been
proposed that include patterning the wires incurved lines, rather
than strait lines; or forming the wires in a lattice structure with
reinforcing members. See US Patent Application Publication US
2002/0167727 A2; and U.S. Pat. Nos. 6,972,906; 7,009,768; and PCT
Application PCT/US2005/032656 (WO 2006/036546).
[0009] Other types of wire-grid polarizers have been proposed to
diffusely reflect incident light that include contoured surfaces at
different angles. See U.S. Pat. Nos. 6,081,376 and 6,348,995. Such
polarizers, however, still specularly reflect, only from within
several differently oriented textured surfaces.
[0010] Sometimes it is desirable to reflect all incident light or
transmit most or all incident light in a diffuse manner. In this
situation a diffuser is desired, but not a polarizing diffuser. One
example of this situation would be a thermal window with a metallic
film. Without a diffuser, a specular reflection would result from
the building windows. Another need for diffuse light may be in an
LCD display or a projector system.
SUMMARY OF THE INVENTION
[0011] It has been recognized that it would be advantageous to
develop a wire-grid polarizer for polarizing incident light by
diffusely transmitting one polarization orientation and diffusely
reflection the other polarization orientation.
[0012] It has also been recognized that it would be advantageous to
develop a non-polarizing diffuser to either transmit or reflect
light diffusively.
[0013] The invention provides a light diffuser comprising: a
substrate having a top surface and a bottom surface; a layer
disposed over the top surface of the substrate; and at least
sixteen facets: having at least two different sizes; having a
bottom surface disposed towards the substrate and a top surface
opposing the bottom surface; formed in the layer with facet
dimensions >.lamda./2, where .lamda. is the wavelength of light
incident on the at least sixteen facets to create a substantially
diffuse light beam; and forming distinct groups arranged in a
fractal pattern.
[0014] In addition, the invention provides a light diffuser
comprising: a substrate having a top surface and a bottom surface;
at least one layer disposed over the top surface of the substrate;
and at least sixteen facets, with a bottom surface disposed towards
the substrate and a top surface opposing the bottom surface, formed
in one of the at least one layer with facet dimensions
>.lamda./2 where .lamda. is the wavelength of light incident on
the at least two facets to create a substantially diffuse light
beam.
[0015] Furthermore, the invention provides a light diffuser
comprising: a substrate having a top surface and a bottom surface;
a layer, disposed over the top surface of the substrate, and formed
of the same material as the substrate; and at least sixteen facets:
having at least four different sizes with at least four different
surface areas; having a bottom surface disposed towards the
substrate and a top surface opposing the bottom surface; formed in
the layer with facet dimensions >.lamda./2, where .lamda. is the
wavelength of light incident on the at least sixteen facets;
forming distinct groups arranged in a fractal pattern; and
substantially diffracting incident light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Additional features and advantages of the invention will be
apparent from the detailed description which follows, taken in
conjunction with the accompanying drawings, which together
illustrate, by way of example, features of the invention; and,
wherein:
[0017] FIG. 1 is a schematic top view of a diffusive wire-grid
polarizer in accordance with an embodiment of the present
invention;
[0018] FIG. 2 is a schematic cross-sectional side view of the
diffusive wire-grid polarizer of FIG. 1 taken along line 2-2 in
FIG. 1;
[0019] FIG. 3 is a schematic partial perspective view of the
diffusive wire-grid polarizer of FIG. 1;
[0020] FIGS. 4a-f are schematic top views of various shaped
facets;
[0021] FIG. 5 is a schematic top view of a diffusive wire-grid
polarizer in accordance with an embodiment of the present
invention;
[0022] FIG. 6 is a schematic top view of a diffusive wire-grid
polarizer in accordance with an embodiment of the present
invention;
[0023] FIG. 7 is a schematic top view of a diffusive wire-grid
polarizer in accordance with an embodiment of the present
invention;
[0024] FIG. 8 is a schematic top view of a diffusive wire-grid
polarizer in accordance with an embodiment of the present
invention;
[0025] FIG. 9 is a schematic cross-sectional side view of a
diffusive wire-grid polarizer in accordance with an embodiment of
the present invention;
[0026] FIG. 10 is a schematic cross-sectional side view of a
diffusive wire-grid polarizer in accordance with an embodiment of
the present invention;
[0027] FIG. 11 is a schematic cross-sectional side view of a
diffusive wire-grid polarizer in accordance with an embodiment of
the present invention;
[0028] FIG. 12 is a schematic partial perspective view a diffusive
wire-grid polarizer in accordance with an embodiment of the present
invention;
[0029] FIG. 13 is a schematic cross-sectional side view of a
diffusive wire-grid polarizer in accordance with an embodiment of
the present invention;
[0030] FIG. 14 is a schematic cross-sectional side view of a
diffusive wire-grid polarizer in accordance with an embodiment of
the present invention;
[0031] FIG. 15 is a schematic cross-sectional side view of a
diffusive wire-grid polarizer in accordance with an embodiment of
the present invention;
[0032] FIG. 16 is a schematic top view of a diffuser in accordance
with an embodiment of the present invention;
[0033] FIG. 17 is a schematic cross-sectional side view of the
diffuser of FIG. 16 taken along line 17-17 in FIG. 16;
[0034] FIG. 18 is a schematic top view of a diffuser in accordance
with an embodiment of the present invention;
[0035] FIG. 19 is a schematic cross-sectional side view of the
diffuser of FIG. 18 taken along line 19-19 in FIG. 18;
[0036] FIG. 20 is a schematic top view of a diffuser in accordance
with an embodiment of the present invention;
[0037] FIG. 21 is a schematic cross-sectional side view of the
diffuser of FIG. 20 taken along line 21-21 in FIG. 20;
[0038] FIG. 22 is a schematic cross-sectional side view of a
diffuser in accordance with an embodiment of the present
invention
[0039] Reference will now be made to the exemplary embodiments
illustrated, and specific language will be used herein to describe
the same. It will nevertheless be understood that no limitation of
the scope of the invention is thereby intended.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0040] As illustrated in FIGS. 1-3, a diffusive wire-grid polarizer
(WGP), indicated generally at 10, in an example implementation in
accordance with the invention is shown. The diffusive WGP of the
present invention can be used in situations in which non-specular,
or non-mirror like, reflection of substantially one polarization
orientation (namely a diffuse reflected beam 29 of s-polarization
orientation) is desired of an incident beam 27. The diffusive WGP
of the present invention can also be used in situations in which
non-specular, or non-mirror like, transmission of substantially one
polarization orientation (namely a diffuse transmitted beam 28 of
p-polarization orientation) is desired of an incident beam 27. In
such a situation, diffuse reflection or diffuse transmission may be
more important than polarization contrast because the diffuse
reflected beam 29 may also include a substantial amount of
p-polarization orientation in addition to the s-polarization
orientation. The incident beam 27 can be unpolarized, and can be
visible light (or have one or more wavelengths in the range of
.about.300-700 nm, or .about.0.3-0.7 microns or .mu.m).
Alternatively, the incident beam can be infrared or ultraviolet. In
this patent application, light means ultraviolet, visible, or
infrared.
[0041] The diffusive WGP 10 can include a substrate 26, such as
glass, or another material that is substantially transparent to the
incident light beam 27. Substrate 26 can be a single layer or can
be multiple layers, with each layer made of the same material as,
or different materials than, the other layers. Disposed on or over
the substrate is a layer 25 of conductive material, such as
aluminum or silver. The layer 25 can be deposited directly on the
substrate. Alternatively, other layers can be disposed between the
substrate 26 and the layer 25 of conductive material. The layer 25
can have a uniform and constant thickness t, and disposed over
essentially the entire substrate.
[0042] The layer 25 can be patterned (such as by etching select
areas) to form an array of facets 14a-d arrayed across the
substrate. The facets can be made of multiple sizes in order to
optimize light diffraction. The facets 14a-d extend essentially
across the entire substrate with spaces or gaps 11 therebetween.
The facets can be arranged in a fractal pattern. "Fractal" means
geometrical structures whose shape appears to be the same
regardless of the level of magnification used to view them. The
facets 14a-d can have widths w.sub.1-4 or diameters and lengths
L.sub.1-4 greater than a wavelength .lamda. of incident light, or
greater than half the wavelength of incident light (w>.lamda./2
and L>.lamda./2, where w is a width or diameter or dimension of
the facets transverse to the wires, and L is a length of the facets
transverse to the width). Thus, the facets substantially diffract
both the s-polarized light and the p-polarized light incident on
the facets, or the light having s-polarization orientation and
p-polarization orientation. A majority or substantially all of the
light having s-polarization orientation will be diffracted, or
diffusely reflected; while a portion of the light having
p-polarization orientation will be transmitted, or diffusely
transmitted. The type of fractal pattern used and material of the
layer 25 affect the amount of p-polarized light that is
transmitted.
[0043] In addition, layer 25 can be patterned to form a wire-grid
including an array of elongated parallel conductive wires 12
filling the spaces 11 between the facets 14a-d. Thus, the array of
wires 12 extends across essentially the entire substrate. The
facets 14a-d and the array of wires 12 can be formed together with
each facet integral with the plurality of wires. The array of
facets 14a-d interrupt and are interspersed through the array of
wires 12. The plurality of facets interrupts the array of wires,
and share a common layer.
[0044] The array of wires 12 has a period P less than half the
wavelength .lamda./2 of incident light (P.sub.WGP<.lamda./2,
where P.sub.WGP is the period of the wires, and .lamda. is the
wavelength of light incident on the wires). Thus, the array of
wires at least partially polarizes the incident light 27 by
substantially reflecting light 29 having an s-polarization
orientation and substantially transmitting light 28 having a
p-polarization orientation.
[0045] The array of wires and array of facets can be formed by
lithography.
[0046] The facets 14a-d can have at least two different sizes with
at least two different surface areas, such as four different facets
with four different sizes and four different surface areas, as
shown. The facets can have rectilinear shapes, such as square with
the width and length of each facet being essentially equal, or on
the same order of magnitude. As shown in FIG. 4a-f, the facets can
also be circular 46, triangular 42, diamond shaped 43, polygonal
45, elliptical 44, irregular shaped 41, or other shape. Different
shapes may be selected for improved optical performance or ease of
manufacturability. Facet dimensions d.sub.1-9 are greater than a
wavelength .lamda. of incident light, or greater than half the
wavelength of incident light (d>.lamda./2). Although most
figures show square shaped facets, any shaped facet may be used in
all invention embodiments. Although most figures show two to four
different sized facets, any number of different sized facets may be
used in all invention embodiments.
[0047] FIG. 1 shows square shaped facets 14a-d, with widths
w.sub.1-4 transverse to the wires and lengths L.sub.1-4 transverse
to the width, arranged in a fractal pattern. FIG. 5 shows a
diffusive WGP, indicated generally at 50, in another example
implementation in accordance with the invention. This diffusive WGP
has square shaped facets 54a-d, arranged in a fractal pattern.
While the width of the square shape is not orthogonal to the wires,
and the length of the square shape is not parallel to the wires,
the square shape has a diameter or dimension transverse to the
wires that is greater than a wavelength .lamda. of incident light,
or greater than half the wavelength of incident light.
[0048] FIG. 6 shows a diffusive WGP, indicated generally at 60, in
another example implementation in accordance with the invention.
This diffusive WGP has triangular shaped facets 64a-d, arranged in
a fractal pattern. As described above, the triangular shaped faces
have a diameter or dimension (such as d.sub.3 or d.sub.4 of FIG. 4)
transverse to the wires that is greater than a wavelength .lamda..
of incident light, or greater than half the wavelength of incident
light. Different fractal patterns may be selected for improved
optical performance or ease of manufacturability.
[0049] As illustrated in FIGS. 7-8, indicated generally at 70 and
80 respectively, fractal patterns different from that shown in
FIGS. 1 and 6 may be used. In the example of FIG. 7, the wire
gridded area 74 of the diffusive WGP 70 comprises a fractal pattern
and the area between the fractal pattern 71 comprises facets 72.
The facets 72 form distinct groups or areas 74 in the array of
wires which include or define the fractal pattern, and can include
at least sixteen facets with four different sizes arranged in a
fractal pattern. The facets 72 can have the same shape.
Alternatively, as shown in FIG. 8, the facets 84 of the diffusive
WGP 80 may comprise a fractal pattern and the area between the
fractal pattern 81 may comprise a wire grid. Optical properties,
such as transmissivity or extinction, may be optimized by selection
of the wire grid or facets to form a fractal pattern. In all
embodiments of this invention, the facets or the wire grid may
comprise a fractal.
[0050] As illustrated in FIG. 9, another diffusive wire-grid
polarizer, shown generally at 90, has facets 94a-c disposed over a
wire grid layer 92 with an array of elongated parallel conductive
wires as described above. The facets 94a-c can be any material with
the desired optical properties. Use of a transparent material for
facets 94a-c can result in higher transmission of the p-polarized
light. In this embodiment, the wire grid layer 92 can extend over
all, or substantially all, of the surface of the substrate 26. To
make such a device, a first layer 92 may be added to a substrate 26
by sputtering, chemical vapor deposition, evaporation, or other
similar method. The first layer 92 may be patterned and etched to
form the wire grid. Another layer 95 may be added on top of the
wire grid layer by sputtering, chemical vapor deposition,
evaporation, or other similar method. The top layer 95 may be
patterned and etched to form the facets 94a-c. The facets may
comprise a fractal pattern, as described above. The exposed wire
grid, in areas where there are no facets, may comprise a fractal
pattern, as described above. Different facets may all be etched to
the same depth such that the facet thicknesses t.sub.1-3 are the
same, as shown in FIG. 9. Different facets may be etched to
different depths such that the facet thicknesses t.sub.1-3 are not
the same. This may be done by use of separate masking and etching
steps for different depth facets. Facets of different sizes or
shapes help to create diffuse transmitted or reflected light.
Facets of different depths also create diffuse transmitted or
reflected light because the light travels through different
thicknesses t.sub.1-3 of material.
[0051] As illustrated in FIG. 10, another diffusive wire-grid
polarizer, shown generally at 100, has facets 104a-b disposed over
the wire grid layer 92 in multiple layers. The facets 104a-b may be
any material with the desired optical properties. There may be more
than two layers of facets. All layers may be the same material or
the layers of facets may be made of different materials. Multiple
layers can provide improved light control and improved wavelength
specificity. To make such a device, additional layer deposition,
patterning, and etching steps can be used following making the
basic structure 90 of FIG. 9.
[0052] As illustrated in FIG. 11, another diffusive wire-grid
polarizer, shown generally at 110, has facets 114a-b disposed below
the wire grid layer 92. To make such a device, a lower facet layer
or multiple lower facet layers are added on top of the substrate 26
by deposition, patterning, and etching steps. Another layer 113 is
then added on top of the facets. Layer 113 can be the same as the
substrate 26 or can be a different material as shown by dividing
line 111. A wire grid layer 92 and facet layers 114c-d may be added
on top of layer 113. In a similar fashion, other layers 113b-c may
be added on top to allow added wire grid layers 92b, facet layers,
and/or combined facet plus wire grid layers 115. The facets 114a-d
may be any material with the desired optical properties. This
stacking of wire grid layers 92b, facet layers, and/or combined
facet plus wire grid layers may apply to other embodiments of the
invention. Multiple layers can provide improved light control and
improved wavelength specificity.
[0053] As illustrated in FIG. 12, another diffusive wire-grid
polarizer, shown generally at 120, has facets 124a created by
etching away facet areas rather than by masking facet areas such as
in FIGS. 1-2. In other embodiments of this invention, facets may
also be created by etching the desired facet area and masking
between facet areas. Thus, areas of the upper surface of the
substrate without wires 12 can form the facets 124a. This
embodiment can have an advantage of improved transmissivity.
[0054] As illustrated in FIG. 13, another diffusive wire-grid
polarizer, shown generally at 130, has facets 134a-c formed by
etching into the substrate 26 or into a layer 133 on top of the
substrate. Layer 133 may be the same as the substrate 26 or may be
a separate material separated at dashed line 131. Different facets
may all be etched to the same depth (not shown but such that the
etch depths or substrate thicknesses t.sub.2-4 at the facets are
the same). Different facets may be etched to different depths, as
shown, such that etch depths or substrate thicknesses t.sub.2-4 at
the facets are not the same. This may be done by use of separate
masking and etching steps for different depth facets. Facets of
different sizes or shapes help to create diffuse transmitted or
reflected light. Facets of different depths also create diffuse
transmitted or reflected light because the light travels through
different thicknesses t.sub.1-4 of material.
[0055] As illustrated in FIG. 14, another diffusive wire-grid
polarizer, shown generally at 140, has thicknesses t.sub.2-4 of the
substrate 26 beneath the facets 144a-c that are thicker than the
thickness t.sub.1 of the substrate beneath the wire grid. This
polarizer may be created by separate pattern and etch steps. For
example, one pattern and etch step may be used to create facets of
the thickness of facet 144b. A different pattern and etch step may
be used to etch to the top of the desired wire grid 141. Another
pattern and etch step may then be used to etch down to level 142 to
create the wire grid 12. Facets of different thicknesses, as shown
in FIGS. 13 & 14 may be used with other embodiments of the
invention. Facets of different depths also create diffuse
transmitted or reflected light because the light travels through
different thicknesses t.sub.1-4 of material.
[0056] As illustrated in FIG. 15, another diffusive wire-grid
polarizer, shown generally at 150, has a wire grid 153a-c disposed
over facets in addition to the areas between the facets. This
polarizer may be created by separate pattern and etch steps. For
example, one pattern and etch step may be used to etch to the top
of the desired wire grid 151. Another pattern and etch step may
then be used to etch down to level 152 to create the wire grid
153b. Wire grids may be disposed over the facets of other invention
embodiments. Use of wire grid over the facets can improve
polarization contrast.
[0057] All of the previously described embodiments may be
non-polarizing diffusers instead of diffusive wire grid polarizers
through use of a non polarizing material, such as a non-conductive
material, to make the wire grid layer. Alternatively, the following
described embodiments are alternative non-polarizing diffusers.
[0058] As illustrated in FIGS. 16-17, a diffuser, shown generally
at 160, has facets used to create a non-polarizing diffuser. This
embodiment may be useful if diffuse, non-polarized light is
desired. A diffuser has a substrate 176 which may be made of
materials that are, or are not, transparent to the incoming light
27. If the substrate is not transparent (or is opaque), then
substantially all of the incoming light 27 can be reflected
diffusely 179. If the substrate is transparent, then some of the
incoming light can be reflected diffusely 179 and some or
substantially all can be transmitted diffusely 178. The reflected
and transmitted light will not be polarized. To make this device
160, facet layer 175 is etched completely between the facets 11
rather than patterned to form wire grids. Because polarization is
not desired, facet layer 175 can be substantially any material that
will provide the desired optical properties. Facet layer 175 and
the substrate 176 can be the same material or may be different
materials. Facet layer 175 can be deposited directly on the
substrate 176. Alternatively, other layers can be disposed between
the substrate 176 and layer 175.
[0059] As illustrated in FIGS. 18-19, the facets 184a-d of another
diffuser 180 are the locations that are cut into a layer or
substrate rather than raised areas which were masked during
etching. Facet layer 175 and substrate (or underlying layer) 176
may be the same, or facet layer 175 may be a different material
from the substrate or underlying layer 176. Similar to the
diffusive WGP 130 of FIG. 13, the thicknesses t.sub.2-5 may be the
same or may be different. This diffuser 180 may be manufactured
similarly to polarizer 130, except that no wire grids are formed.
Facets of different sizes or shapes help to create diffuse
transmitted or reflected light. Facets of different depths also
create diffuse transmitted or reflected light because the light
travels through different thicknesses t.sub.1-4 of material.
[0060] As illustrated in FIGS. 20-21, the facets of 204a-d another
diffuser 200 are the locations that were masked during etching and
thus are raised above surrounding etched locations. This diffuser
200 may be manufactured similarly to polarizer 140, except that no
wire grids are formed. Facets of different sizes or shapes help to
create diffuse transmitted or reflected light. Facets of different
depths also create diffuse transmitted or reflected light because
the light travels through different thicknesses t.sub.1-4 of
material.
[0061] As illustrated in FIG. 22, the facets of another diffuser
220 may be disposed on top of other facets. Facets 224a-b may be
any material with the desired optical properties. There may be more
than two layers of facets. All layers may be the same material or
the layers of facets may be made of different materials. This
diffuser 220 may be manufactured similarly to polarizer 100, except
that no wire grids are formed. Multiple layers can provide improved
light control and improved wavelength specificity.
[0062] While the forgoing examples are illustrative of the
principles of the present invention in one or more particular
applications, it will be apparent to those of ordinary skill in the
art that numerous modifications in form, usage and details of
implementation can be made without the exercise of inventive
faculty, and without departing from the principles and concepts of
the invention. Accordingly, it is not intended that the invention
be limited, except as by the claims set forth below.
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