Multispectral imaging device with array of microlenses
The invention relates to a multispectral imaging device including: a photosensitive detector DET made up of a matrix of pixels; an array of microlenses ML 1 , ML 2 , ML 3 reproducing the matrix of pixels; and a filter module MF formed by a matrix of individual filters λ 1, λ2, λ3 reproducing the matrix of pixels. The device is remarkable in that the array of microlenses is arranged directly in contact with the detector DET, and the filter module MF is made on a substrate SS that is put into contact with the array of microlenses.
1. A multispectral imaging device comprising:
a photosensitive detector made up of a matrix of pixels formed on a first substrate, each pixel comprising a photosensitive zone;
an array of microlenses, each of the microlenses overlapping one corresponding pixel of the matrix of pixels, each of the microlenses configured for focusing incident light on a photosensitive zone of the corresponding pixel, each lens being a plano-convex lens with a flat side facing the photosensitive detector; and
a filter module formed by a matrix of individual filters each facing one pixel of the matrix of pixels;
wherein the filter module comprises a bidimensional matrix of at least four generally identical filter cells, each of the filter cells having at least two of the individual filters;
wherein the filter module is formed on a second substrate and faces said array of microlenses, with one of the individual filters in direct contact with a convex side of a corresponding one of the microlenses; and
said filter module is adhesively bonded to said detector by adhesive located at an outside edge of the filter module, so that there is no adhesive between the filter module and the photosensitive zones of the photosensitive detector.
2. A device according to claim 1 , characterized in that said filter module is provided with alignment patterns.
3. A device according to claim 1 , characterized in that said filter module is made up of two mirrors spaced apart by a spacer, the filter module having a plurality of filter cells and each of said filter cells having at least two filters.
4. A device according to claim 3 , characterized in that at least one of said filters has a bandpass transfer function.
5. A device according to claim 3 , characterized in that at least some of said filter cells are in alignment in a first strip.
6. A device according to claim 5 , characterized in that at least some of said filter cells are in alignment in a second strip parallel to and at a distance from the first strip.
7. A device according to claim 3 , characterized in that at least two of said filters that are adjacent are separated by a crosstalk barrier.
8. A device according to claim 3 , characterized in that at least one of said filters is panchromatic.
9. A device according to claim 1 , characterized in that said detector is integrated in CMOS technology.