Integral field spectral imager
An integral field spectral imager has a plurality of optical homogenizers. Each optical homogenizer is in-register with a corresponding different superpixel in a superpixel array and is configured to spatially homogenize incident EMR and to pass the spatially homogenized EMR to a spectral filter in an array of spectral filters, thence to the in-register, corresponding different superpixel. Baffles are included to maximize confinement of the spatially homogenized EMR passed by a single optical homogenizer to the in-register, corresponding different superpixel so as to minimize crosstalk between superpixels. Optical homogenizers and baffles are designed to produce a pattern of homogenized EMR on a superpixel, regardless of where incident EMR is received on an optical homogenizer. Methods for using embodiments of the spectral imager in a variety of spectral bands in the EMR spectrum enable determining spectral information about incident EMR.
1 . A spectral imager comprising:
an image sensor comprising a superpixel array having a plurality of superpixels, each superpixel comprising at least four pixels;
a plurality of optical homogenizers, each optical homogenizer being in-register with a corresponding different superpixel in the superpixel array, being positioned to receive electromagnetic radiation (EMR), and being configured to spatially homogenize the received EMR and to pass the spatially homogenized EMR to the in-register, corresponding different superpixel;
an optical filter array positioned between each optical homogenizer and the in-register, corresponding different superpixel and comprising a plurality of spectral filters, wherein at least four spectral filters in the plurality of spectral filters are configured to spectrally filter the spatially homogenized EMR differently from one another and to pass the spectrally filtered, spatially homogenized EMR to the in-register, corresponding different superpixel, and wherein each of the at least four pixels is in-register with a different one of the at least four differently configured spectral filters and is positioned to receive the spectrally filtered, spatially homogenized EMR passed by the in-register spectral filter; and,
a plurality of baffles, each baffle being configured and positioned to maximize confinement of the spatially homogenized EMR passed by a single optical homogenizer in the plurality of optical homogenizers to the in-register, corresponding different superpixel.
2 . The spectral imager of claim 1 , wherein one or more of the at least four spectral filters are further configured to spectropolarimetrically filter the spatially homogenized EMR.
3 . The spectral imager of claim 1 , wherein the optical filter array further comprises one or more polarization filters, the one or more polarization filters each being in register with a single, corresponding different pixel of the at least four pixels.
4 . The spectral imager of claim 1 , wherein at least one baffle is further configured to spatially homogenize the received EMR.
5 . The spectral imager of claim 1 , wherein at least one baffle is dome-shaped.
6 . The spectral imager of claim 1 , wherein at least one baffle comprises an inner surface having a reflective coating.
7 . The spectral imager of claim 1 , wherein at least one baffle comprises an EMR-absorbing inner surface.
8 . The spectral imager of claim 7 , wherein the EMR-absorbing inner surface comprises CuO.
9 . The spectral imager of claim 1 , further comprising a microlens array having one or more microlenses, wherein each microlens is configured to receive incident EMR and pass the received, incident EMR to an in-register, corresponding different optical homogenizer.
10 . The spectral imager of claim 1 , further comprising an imaging optic.
11 . The spectral imager of claim 1 , further comprising a camera.
12 . The spectral imager of claim 1 , further comprising a non-structural street.
13 . The spectral imager of claim 1 , further comprising a structural street.
14 . The spectral imager of claim 1 , wherein each optical homogenizer in the plurality of optical homogenizers comprises at least one of a surface homogenizer, a volume homogenizer, or a baffle inner surface configured to cause or enhance spatial homogenization of the received EMR.
15 . The spectral imager of claim 14 , wherein at least one optical homogenizer in the plurality of optical homogenizers comprises a volume homogenizer.
16 . The spectral imager of claim 14 , wherein at least one optical homogenizer in the plurality of optical homogenizers comprises a surface homogenizer.
17 . The spectral imager of claim 1 , configured to operate in at least one of the ultraviolet region, the visible region, or the infrared region of the EMR spectrum.
18 . The spectral imager of claim 17 configured to operate in the VNIR band of the EMR spectrum.
19 . The spectral imager of claim 17 , configured to operate in the LWIR band of the EMR spectrum.
20 . A method of determining spectral information about EMR incident on the spectral imager of claim 1 , the method comprising the steps of:
exposing the spectral imager of claim 1 to incident EMR;
measuring an electrical response of the at least four pixels in each corresponding different superpixel to the spectrally filtered, spatially homogenized EMR passed to the at least four pixels;
based on analysis of the electrical responses of the at least four pixels in each corresponding different superpixel, determining spectral information about the EMR received by the optical homogenizer and passed to the in-register corresponding different superpixel.