Optical design of a light field otoscope
Designs for a light field otoscope are disclosed. An example light field otoscope includes an objective lens group, relay optics and a plenoptic sensor (e.g., microlens array and sensor array). The objective lens group images an interior of a human ear and is characterized by a pupil plane and an image plane. The relay optics is positioned between the objective lens group and the plenoptic sensor. It relays the image plane to the microlens array and relays the pupil plane to the sensor array.
1. A light field otoscope comprising:
an objective lens group for imaging an interior of a human ear, the objective lens group characterized by a pupil plane and an image plane;
a plenoptic sensor comprising a microlens array and a sensor array; and
relay optics positioned between the objective lens group and the plenoptic sensor, the relay optics relaying the image plane to the microlens array and relaying the pupil plane to the sensor array, wherein the relay optics comprises:
a first relay lens group that relays the pupil plane to an intermediate pupil plane; and
a second relay lens group that relays the intermediate pupil plane to the sensor array, the first and second relay lens groups together relaying the image plane to the microlens array, and wherein a filter module is insertable at the intermediate pupil plane.
2. The light field otoscope of claim 1 wherein the pupil plane is located ahead of a front lens of the objective lens group.
3. The light field otoscope of claim 1 wherein the objective lens group consists of a doublet followed by a singlet.
4. The light field otoscope of claim 1 wherein the objective lens group is specified substantially according to a lens prescription of:
Surf
Type
Radius
Thickness
Glass
Conic
1
STANDARD
5.33
1.00
N-BK7
−17.08
2
STANDARD
−4
1
N-5F5
3
STANDARD
−3.7
2
4
STANDARD
7
0.92
N-BK7
5
STANDARD
−7
2.2.
5. The light field otoscope of claim 1 wherein the objective lens group consists of a first positive lens group and a second positive lens group, the pupil plane located ahead of both lens groups.
6. The light field otoscope of claim 1 wherein the objective lens group has an object-space numerical aperture of at least 0.05.
7. The light field otoscope of claim 1 wherein the objective lens group has a field of view of at least 16 mm.
8. The light field otoscope of claim 1 wherein the objective lens group has an RMS spot size of not more than 6 microns on-axis.
9. The light field otoscope of claim 1 wherein chief rays in an image space of the objective lens group are telecentric or near-telecentric.
10. The light field otoscope of claim 1 wherein the objective lens group is specified substantially according to a lens prescription of:
Surf
Type
Radius
Thickness
Glass
1
STANDARD
5.38
1
S-PHM52
2
STANDARD
−5.38
1
N-LASF9
3
STANDARD
−20.79
1.2
4
STANDARD
5.26
1.47
N-BK7
5
STANDARD
−3.98
1.03
N-SF5
6
STANDARD
−12.05
0.8
7
STANDARD
7.12
2
N-BAF10
8
STANDARD
−4.22
1
N-SF10
9
STANDARD
−33.66.
11. The light field otoscope of claim 1 wherein the objective lens group consists of a first negative lens group and a second positive lens group separated by the pupil plane.
12. The light field otoscope of claim 1 wherein the objective lens group is specified substantially according to a lens prescription of:
Surf
Type
Radius
Thickness
Glass
1
STANDARD
−1.51
0.5
N-BK7
2
STANDARD
−1.66
0.5
3
STANDARD
Infinity
0
4
STANDARD
3.45
1.37
N-BK7
5
STANDARD
−1.38
0.83
N-SF5
6
STANDARD
−2.87
2
7
STANDARD
10.14
1.68
N-BK7
8
STANDARD
−16.85
1
N-SF5
9
STANDARD
−10.65
0.7.
13. The light field otoscope of claim 1 wherein the objective lens group has an object-space numerical aperture of at least 0.03.
14. The light field otoscope of claim 1 wherein the objective lens group has a field of view of at least 30 degrees.
15. The light field otoscope of claim 1 wherein the objective lens group has an RMS spot size of not more than 30 microns.
16. The light field otoscope of claim 1 wherein the objective lens group has a magnification of between −0.1 and −1.0.
17. The light field otoscope of claim 1 wherein the objective lens group has vignetting of not more than 20% at focus plane.
18. The light field otoscope of claim 1 wherein the light field otoscope has an aperture of at least 3 mm in diameter.
19. The light field otoscope of claim 1 further comprising:
an inner housing containing the objective lens group, the inner housing shaped to be covered by a speculum.
20. A system for diagnosing conditions of the ear, comprising the light field otoscope of claim 1 and a computing system coupled to the light field otoscope, the light field otoscope capturing plenoptic images of an interior of the ear of a patient, the computing system processing the plenoptic images to assist in diagnosis of conditions of the ear.