Oblique camera lens
A oblique camera lens includes: a primary mirror configured to reflect a light ray to form a first reflected light; a secondary mirror located on a first path of light reflected from the primary mirror and configured to reflect the first reflected light to form a second reflected light; a tertiary mirror located on a second path of light reflected from the secondary mirror and configured to reflect the second reflected light to form a third reflected light; and an image sensor located on a third path of light reflected from the tertiary mirror and configured to receive the third reflected light; wherein each of the first reflecting surface and the third reflecting surface is a sixth order xy polynomial freeform surface; and a field of view of oblique camera lens in an Y-axis direction is greater or equal to 35° and less than or equal to 65°.
1. An oblique camera lens comprising:
a primary mirror located on a path of a light ray from an object space and configured to reflect the light ray to form a first reflected light, wherein the primary mirror comprises a first reflecting surface;
a secondary mirror located on a first path of light reflected from the primary mirror and configured to reflect the first reflected light to form a second reflected light, wherein the secondary mirror comprises a second reflecting surface, and the secondary mirror is an aperture stop;
a tertiary mirror located on a second path of light reflected from the secondary mirror and configured to reflect the second reflected light to form a third reflected light, wherein the tertiary mirror comprises a third reflecting surface; and
an image sensor located on a third path of light reflected from the tertiary mirror and configured to receive the third reflected light;
wherein a horizontal line passing through a center of the secondary mirror is defined as a Z-axis, a distance between the primary mirror and the secondary mirror along the Z-axis is in a range from about 399 mm to about 400 mm; each of the first reflecting surface and the third reflecting surface is a sixth order xy polynomial freeform surface, the second reflecting surface is a spherical surface; and a field of view of oblique camera lens in an Y-axis direction is greater or equal to 35° and less than or equal to 65°.
2. The oblique camera lens as claimed in claim 1 , wherein the sixth order xy polynomial freeform surface satisfies an equation:
z
(
x
,
y
)
=
c
(
x
2
+
y
2
)
1
+
1
-
(
1
+
k
)
c
2
(
x
2
+
y
2
)
+
A
2
y
+
A
3
x
2
+
A
5
y
2
+
A
7
x
2
y
+
A
9
y
3
+
A
10
x
4
+
A
12
x
2
y
2
+
A
14
y
4
+
A
16
x
4
y
+
A
18
x
2
y
3
+
A
20
y
5
+
A
21
y
5
+
A
23
x
4
y
2
+
A
25
x
2
y
4
+
A
27
y
6
wherein, c represents surface curvature, k represents conic constant, and A 2 ˜A 27 represent coefficients.
3. The oblique camera lens as claimed in claim 2 , wherein in the equation of the primary mirror reflecting surface, c, k, and A 2 ˜A 27 are:
c
0.0017454722941919
k
−0.370220176947202
A 2
0.00899999999999976
A 3
−0.000658642004976331
A 5
−0.000388156831578603
A 7
−1.00845234050156e−006
A 9
3.44785143052323e−007
A 10
−9.09497498375104e−008
A 12
−2.1461965705095e−009
A 14
−2.58936718900012e−009
A 16
6.17247458427895e−010
A 18
5.8161341718006e−012
A 20
−1.42226439288969e−012
A 21
−1.67670181068018e−011
A 23
−1.61489706272178e−012
A 25
−3.61090101535634e−014
A 27
2.96725075844174e−014.
4. The oblique camera lens as claimed in claim 2 , wherein in the equation of the tertiary mirror reflecting surface, c, k, and A 2 ˜A 27 are:
c
−0.0022663233954444
k
−0.137877911427001
A 2
−0.000876604317960913
A 3
−0.000327909476515856
A 5
−0.00028841099866956
A 7
1.65465628748813e−006
A 9
1.05474315966924e−006
A 10
5.71091387012652e−008
A 12
−6.61918406198728e−009
A 14
−3.12149077600531e−009
A 16
5.79412604911529e−011
A 18
1.41667391666226e−011
A 20
−5.78183876722764e−012
A 21
−3.9085412033913e−012
A 23
1.3549236784204e−012
A 25
−1.91373381734072e−013
A 27
−1.04655761173843e−013.
5. The oblique camera lens as claimed in claim 1 , wherein an equation of the spherical surface is
z
(
x
,
y
)
=
c
(
x
2
+
y
2
)
1
+
1
-
c
2
(
x
2
+
y
2
)
,
z represents surface sag, c represents surface curvature.
6. The oblique camera lens as claimed in claim 5 , wherein c=5.03064529008e-5.
7. The oblique camera lens as claimed in claim 1 , wherein a horizontal line passing through a center of the secondary mirror is defined as a Z-axis, a distance between the secondary mirror and the tertiary mirror along the Z-axis is in a range from about 373 mm to about 374 mm.
8. The oblique camera lens as claimed in claim 1 , wherein a horizontal line passing through a center of the secondary mirror is defined as a Z-axis, a distance between the tertiary mirror and the image sensor along the Z-axis is in a range from about 156 mm to about 157 mm.
9. The oblique camera lens as claimed in claim 1 , wherein an effective entrance pupil diameter of the off-axis three-mirror optical system with freeform surfaces is about 13 mm.
10. The oblique camera lens as claimed in claim 1 , wherein an effective focal length of the off-axis three-mirror optical system with freeform surfaces is about 75 mm.
11. The oblique camera lens as claimed in claim 1 , wherein materials of the primary mirror, the secondary mirror, or the tertiary mirror is aluminum, beryllium, or other metals.