Optical system and optical camera working at far-infrared waveband
An optical system and an optical camera working at a far-infrared waveband are provided, the optical system along the optical axis from the objection side to the image side includes: a metalens and a spherical lens; the metalens is configured to correct higher-order residual wavefront aberrations; the spherical lens is configured to correct lower-order primary wavefront aberrations; the metalens and the spherical lens are configured to correct aberrations; an absolute value of the curvature radius of an objection-side surface towards the objection side for the spherical lens is greater than an absolute value of the curvature radius of an image-side surface towards the image side for the spherical lens; the optical system satisfies the following condition: 0.83≤f/D≤0.92; where f is an effective focal length of the optical system, and D is the entrance pupil diameter of the optical system.
1 . An optical system working at a far-infrared waveband, wherein the optical system along an optical axis from an objection side to an image side comprises: a metalens and a spherical lens;
the metalens is configured to correct a plurality of higher-order residual wavefront aberrations;
the spherical lens is configured to correct a plurality of lower-order primary wavefront aberrations;
the metalens and the spherical lens are configured to correct a plurality of aberrations;
an absolute value of a curvature radius of an objection-side surface towards the objection side for the spherical lens is greater than an absolute value of a curvature radius of an image-side surface towards the image side for the spherical lens;
the optical system satisfies the following condition expression:
0.83
≤
f
/
D
≤
0
.
9
2
wherein f is an effective focal length of the optical system, and D is an entrance pupil diameter of the optical system.
2 . The optical system according to claim 1 , wherein the optical system further satisfies:
4.2
<
f
M
Δφ
/
R
M
<
6
.
9
wherein f M is a focal length of the metalens, Δφ is a biggest phase variation of the metalens at a single wavelength, and R M is an effective radius of the metalens.
3 . The optical system according to claim 1 , wherein the optical system further satisfies:
1.
<
r
1
/
r
2
<
2
.
8
wherein r 1 is the curvature radius of the objection-side surface towards the objection side for the spherical lens, and r 2 is the curvature radius of the image-side surface towards the image side for the spherical lens.
4 . The optical system according to claim 1 , wherein the optical system further satisfies:
0.4
≤
R
M
/
R
G
≤
0
.
5
5
wherein R M is an effective radius of the metalens, and R G is an effective radius of the spherical lens.
5 . The optical system according to claim 1 , wherein the optical system further satisfies:
1
<
f
M
/
f
≤
1.85
wherein f M is a focal length of the metalens.
6 . The optical system according to claim 1 , wherein the optical system further satisfies:
1.25
≤
f
G
/
f
≤
1.75
wherein f G is a focal length of the spherical lens.
7 . The optical system according to claim 1 , wherein the optical system further satisfies:
3.3
≤
n
M
≤
4
.3
3.3
≤
n
G
≤
4
.
3
wherein n M is a refractive index of the metalens, and n G is a refractive index of the spherical lens.
8 . The optical system according to claim 1 , wherein the optical system further comprises:
an aperture slot; the aperture slot is set on a surface of the metalens.
9 . The optical system according to claim 1 , wherein the optical system further comprises:
an aperture slot; an interval is set between the aperture slot and the metalens.
10 . The optical system according to claim 1 , wherein a total track length of the optical system is less than or equal to 5 mm.
11 . The optical system according to claim 1 , wherein a field of view for the optical system further satisfies:
100
°
≤
FOV
≤
120
°
wherein FOV is the field of view of the optical system.
12 . The optical system according to claim 1 , wherein a relative illumination at an overall field of view of the optical system is greater than 60%.
13 . The optical system according to claim 1 , wherein the metalens and the spherical lens are made of intrinsic silicon.
14 . The optical system according to claim 1 , wherein a plurality of nanostructures are set on an image-side surface of the metalens.
15 . The optical system according to claim 1 , wherein the optical system further satisfies:
2
mm
≤
d
M
≤
0
.
3
75
mm
wherein d M is a central thickness of the metalens.
16 . The optical system according to claim 1 , wherein the optical system further satisfies:
1.2
mm
≤
d
G
≤
2.25
mm
Wherein d G is a central thickness of the spherical lens.
17 . An optical camera working at a far-infrared waveband, wherein the optical camera comprises the optical system according to claim 1 and an imaging detector;
the imaging detector is setting on an image-side surface towards the image side for the metalens.
18 . The optical camera according to claim 17 , wherein the optical camera further comprises an optical window glass, and the optical window glass is set between the optical system and the imaging detector.
19 . The optical camera according to claim 18 , wherein the optical camera further comprises an optical window glass, and the optical window glass is set between the spherical lens and the imaging detector.