Fabrication of lenses using high viscosity liquid
A method for fabricating millimeter and sub-millimeter size lenses using a high viscosity curable liquid, such as epoxy. The method comprises dispensing a predetermined volume of the curable liquid onto a substrate. The curable liquid preferably has a viscosity higher than 100 cps. Additionally, to reduce spherical aberration, the curable liquid can be cured upside down to leverage the effects of gravity.
1. A method for fabricating lenses on a substrate, the method comprising:
making contact between a dispenser and a surface of a substrate;
dispensing a predetermined volume of a curable liquid from the dispenser onto the surface of the substrate while the dispenser is in contact with the surface of the substrate and while the curable liquid is in contact with the surface of the substrate, the curable liquid having a viscosity of at least 100 cps; and
curing the predetermined volume of curable liquid to a solid form, the predetermined volume of curable liquid forming one single lens; and
repeating the above steps, each dispensed predetermined volume of the curable liquid cured to form one single lens.
2. The method of claim 1 , wherein the curable liquid is a liquid epoxy or a liquid polymer.
3. The method of claim 1 , wherein the one single lens has a circular aperture with diameter of not more than 1 mm.
4. The method of claim 1 , wherein the one single lens has a circular aperture with diameter of not more than 500 μm.
5. The method of claim 1 , wherein the curable liquid has a viscosity of at least 200 cps.
6. The method of claim 1 , wherein the curable liquid is cured while supported by the surface of the substrate.
7. The method of claim 1 , wherein the curable liquid is cured while suspended from the surface of the substrate.
8. The method of claim 1 , wherein the substrate is a featureless, planar substrate.
9. The method of claim 1 , wherein the substrate is transparent.
10. The method of claim 1 , wherein the substrate is homogeneous with a uniform refractive index.
11. The method of claim 1 , wherein the substrate is inhomogeneous with a gradient in refractive index.
12. The method of claim 1 , wherein curing the predetermined volumes of curable liquid to a solid form forms an array of lenses, each predetermined volume of curable liquid forming one single lens in the array of lenses.
13. The method of claim 1 , wherein the predetermined volumes of curable liquid are dispensed simultaneously at multiple locations on the substrate.
14. The method of claim 1 , wherein the predetermined volumes of liquid are dispensed sequentially at each of the multiple locations on the substrate.
15. A plurality of lenses manufactured by the process of claim 1 .
16. The plurality of lenses of claim 15 wherein a surface of each single lens is characterized by
z
(
r
)
=
r
/
R
2
1
+
1
-
(
r
/
R
)
2
+
∑
n
=
2
N
a
n
r
2
n
where z(r) is a height of the lens at radius r, R is a radius of curvature at the center of the lens,
a
2
=
-
1
32
R
(
1
R
2
+
1
L
c
2
)
a
3
=
-
1
576
R
(
23
R
4
+
1
2
L
c
4
+
47
R
2
L
c
2
)
a
4
=
-
1
819
R
(
375
R
6
+
1
9
L
c
6
+
3745
9
R
4
L
c
2
+
371
9
R
2
L
c
4
)
and L c is a characteristic length of the epoxy or polymer forming the lens.
17. The plurality of lenses of claim 15 wherein a surface of each single lens is characterized by
z
(
r
)
=
r
/
R
2
1
+
1
-
(
r
/
R
)
2
+
∑
n
=
2
N
a
n
r
2
n
where z(r) is a height of the lens at radius r, R is a radius of curvature at the center of the lens,
a
2
=
-
1
32
R
(
1
R
2
-
1
L
c
2
)
a
3
=
-
1
576
R
(
23
R
4
+
1
2
L
c
4
-
47
R
2
L
c
2
)
a
4
=
-
1
819
R
(
375
R
6
-
1
9
L
c
6
-
3745
9
R
4
L
c
2
+
371
9
R
2
L
c
4
)
and L c is a characteristic length of the epoxy or polymer forming the lens.
18. The plurality of lenses of claim 15 wherein the curable liquid is a liquid epoxy or a liquid polymer.
19. The plurality of lenses of claim 15 wherein the one single lens has a circular aperture with diameter of not more than 1 mm.
20. The plurality of lenses of claim 15 wherein the plurality of lenses is an array of lenses.