Systems and methods for multi-spectral imaging with a non-mechanical adjustable aperture
An adjustable aperture for an imager includes a mechanical aperture having an opening for permitting light to pass through the mechanical aperture; and an electro-optic shutter having a hole in at least one linearly polarizing layer such that at least a portion of light incident on the electro-optic shutter can pass through the electro-optic shutter regardless of an operating state of the electro-optic shutter, wherein an aperture size of the adjustable aperture is defined by the mechanical aperture when the electro-optic shutter is controlled for light transmission and by the electro-optic shutter when the electro-optic shutter is controlled for light blocking.
1 . An adjustable aperture for an imager comprising:
a mechanical aperture having an opening for permitting light to pass through the mechanical aperture; and
an electro-optic shutter comprising a plurality of layers that include at least one linearly polarizing layer, wherein a hole extends through each layer of the plurality of layers of the electro-optic shutter such that at least a portion of light arriving at the electro-optic shutter can pass through the electro-optic shutter regardless of an operating state of the electro-optic shutter,
wherein an aperture size of the adjustable aperture is defined by the mechanical aperture when the electro-optic shutter is controlled for light transmission and by the electro-optic shutter when the electro-optic shutter is controlled for light blocking.
2 . The adjustable aperture of claim 1 , wherein the electro-optic shutter comprises two linearly polarizing layers that both have the hole.
3 . The adjustable aperture of claim 1 , wherein the mechanical aperture is positioned on a surface of the electro-optic shutter.
4 . The adjustable aperture of claim 1 , wherein the opening of the mechanical aperture is fixed in size.
5 . The adjustable aperture of claim 1 , wherein the electro-optic shutter comprises a liquid crystal shutter.
6 . The adjustable aperture of claim 1 , wherein the electro-optic shutter comprises a Pockels cell.
7 . The adjustable aperture of claim 1 , wherein the electro-optical shutter can be controlled to switch the aperture size at a video frame rate.
8 . An imaging system comprising:
at least one imaging sensor;
an adjustable aperture, the adjustable aperture comprising:
a mechanical aperture having an opening for permitting light to pass through the mechanical aperture, and
an electro-optic shutter having a hole in at least one linearly polarizing layer such that at least a portion of light directed through the hole in the at least one linearly polarizing layer can pass through the electro-optic shutter regardless of the operating state of the electro-optic shutter,
wherein an aperture size of the adjustable aperture is defined by the mechanical aperture when the electro-optic shutter is controlled for light transmission and by the electro-optic shutter when the electro-optic shutter is controlled for light blocking; and
a controller comprising one or more processors configured to control the adjustable aperture to adjust the aperture size, wherein the system is configured for capturing a series of frames in alternating spectral bands, and the controller is configured for controlling the adjustable aperture such that the aperture size is defined by the mechanical aperture for at least a first spectral band and by the electro-optic shutter for at least a second spectral band that is different than the first spectral band.
9 . The imaging system of claim 8 , wherein the controller can control the electro-optical shutter to adjust the aperture size at a video frame rate of the at least one imaging sensor.
10 . The imaging system of claim 9 , wherein the video frame rate is at least 60 frames per second.
11 . The imaging system of claim 8 , wherein the first spectral band is a fluorescence light band and the second spectral band is a visible light band.
12 . The imaging system of claim 11 , wherein the fluorescence light band is within or overlaps the visible light band.
13 . The imaging system of claim 8 , wherein the electro-optic shutter comprises two linearly polarizing layers that both have the hole.
14 . The imaging system of claim 8 , wherein the hole extends through each layer of the electro-optic shutter.
15 . The imaging system of claim 8 , wherein the mechanical aperture is positioned on a surface of the electro-optic shutter.
16 . The imaging system of claim 8 , wherein the opening of the mechanical aperture is fixed in size.
17 . The imaging system of claim 8 , wherein the electro-optic shutter comprises a liquid crystal shutter.
18 . The imaging system of claim 8 , wherein the electro-optic shutter comprises a Pockels cell.
19 . The imaging system of claim 8 , wherein the electro-optical shutter can be controlled to switch the aperture size at least at a frame rate of video generated by the imaging system.
20 . A method for imaging using an imager having an adjustable aperture comprising:
capturing a first image while controlling an electro-optic shutter for light blocking such that a hole in at least one linearly polarizing layer of the electro-optic shutter defines an aperture size for the first image; and
capturing a second image while controlling the electro-optic shutter for light transmission such that an opening in a mechanical aperture defines the aperture size for capturing the second image, wherein the first image is generated from light having a first spectral band and the second image is generated from light having a second spectral band that is different than the first spectral band.
21 . The method of claim 20 , further comprising generating a video using the first and second images.
22 . The method of claim 21 , wherein the first and second images are captured sequentially and combined into a frame of the video.
23 . The method of claim 20 , wherein the first and second images are captured sequentially at least at 60 frames per second.
24 . The method of claim 20 , wherein the first spectral band is a visible light band and the second spectral band is a fluorescence light band.
25 . The method of claim 24 , wherein the fluorescence light band is within or overlaps the visible light band.
26 . The method of claim 20 , wherein the electro-optic shutter comprises two linearly polarizing layers that both have the hole.
27 . The method of claim 20 , wherein the hole extends through each layer of the electro-optic shutter.
28 . The method of claim 20 , wherein the mechanical aperture is positioned on a surface of the electro-optic shutter.
29 . The method of claim 20 , wherein the opening of the mechanical aperture is fixed in size.
30 . The method of claim 20 , wherein the electro-optic shutter comprises a liquid crystal shutter.
31 . The method of claim 20 , wherein the electro-optic shutter comprises a Pockels cell.
32 . An adjustable aperture for an imager comprising:
a mechanical aperture having an opening for permitting light to pass through the mechanical aperture; and
an electro-optic shutter comprising at least one linearly polarizing layer, a first polarization rotator, and a second polarization rotator disposed within a central portion of the first polarization rotator, wherein the second polarization rotator is controllable independently of the first polarization rotator.
33 . The adjustable aperture of claim 32 , wherein the at least one linearly polarizing layer does not comprise a hole.
34 . The adjustable aperture of claim 32 , wherein the second polarization rotator is controllable to block all the light.
35 . The adjustable aperture of claim 32 , wherein the electro-optical shutter comprises two linearly polarizing layers disposed on opposing sides of the first and second polarization rotators.
36 . The adjustable aperture of claim 32 , wherein the mechanical aperture is positioned on a surface of the electro-optic shutter.
37 . The adjustable aperture of claim 32 , wherein the opening of the mechanical aperture is fixed in size.
38 . The adjustable aperture of claim 32 , wherein the electro-optic shutter comprises a liquid crystal shutter.
39 . The adjustable aperture of claim 32 , wherein the electro-optic shutter comprises a Pockels cell.