Multispectral imager with enlarged spectral domain
A multispectral imager is provided, designed for analyzing a spectral domain of interest, comprising an image sensor formed of an array of macropixels and comprising a first and a second photosensitive pixel respectively dedicated to a first and a second spectral band, and a filtering structure comprising a first and second interference filter which are superimposed respectively on the first and second photosensitive pixel and which are arranged to respectively transmit a first and second electromagnetic radiation belonging respectively to the first and second spectral bands, the multispectral imager in which a wavelength half of that of the second electromagnetic radiation is located in the spectral domain of interest, and a filtering layer is superimposed on the second photosensitive pixel and configured to block the passage of a third electromagnetic radiation of wavelength half that of the second electromagnetic radiation.
1. A multispectral imager designed to analyze a spectral domain of interest comprising a first spectral band and a second spectral band distinct from the first spectral band, comprising:
an image sensor formed of an array of macro-pixels each comprising a first photosensitive pixel and a second photosensitive pixel dedicated respectively to the first spectral band and to the second spectral band distinct from the first spectral band; and
a filtering structure which comprises, for any given one of the macro-pixels, a first interference filter and a second interference filter which are superimposed respectively on the first photosensitive pixel and on the second photosensitive pixel and which are arranged to transmit respectively a first electromagnetic radiation belonging to the first spectral band and a second electromagnetic radiation belonging to the second spectral band, wherein:
a wavelength half that of the second electromagnetic radiation is in the spectral domain of interest; and
the multispectral imager further comprises a filtering layer which is, for the given one of the macro-pixels, superimposed on the second photosensitive pixel and which is configured to block passage of a third electromagnetic radiation with a wavelength half that of the second electromagnetic radiation, wherein (i) the filtering layer forms an organic high-pass filter configured to block the first electromagnetic radiation and transmit the second electromagnetic radiation or (ii) the filtering layer comprises an array of organic filters configured to each transmit a spectral band in the visible spectral domain,
wherein:
the first photosensitive pixel and the second photosensitive pixel are formed on and/or in a sensor substrate,
the filtering structure comprises a filter substrate on which are formed the first interference filter and the second interference filter,
the sensor substrate and the filter substrate are attached to each other,
the first photosensitive pixel, the second photosensitive pixel, the first interference filter, the second interference filter, and the filtering layer are interposed between the sensor substrate and the filter substrate.
2. The multispectral imager according to claim 1 , wherein the wavelength half that of the second electromagnetic radiation is in the first spectral band.
3. The multispectral imager according to claim 1 , wherein the filtering layer is structured so as not to be superimposed on the first photosensitive pixel.
4. The multispectral imager according to claim 1 , wherein the filtering layer is composed of a layer of red organic material.
5. The multispectral imager according to claim 1 , wherein the filtering layer is formed of a mosaic of elementary filters juxtaposed to one another and that are each one of the interference filters of the filtering structure, one of the elementary filters being superimposed on the first photosensitive pixel and is configured to transmit the first electromagnetic radiation to the first photosensitive pixel.
6. The multispectral imager according to claim 1 , wherein the organic filters are configured to transmit blue, green and red radiation bands respectively.
7. The multispectral imager according to claim 6 , wherein the array of organic filters is a Bayer array.
8. The multispectral imager according to claim 1 , wherein the sensor substrate and the filter substrate are attached to each other by means of a strip of glue.
9. The multispectral imager according to claim 1 , wherein the filtering layer is formed on the sensor substrate.
10. The multispectral imager according to claim 9 , wherein the filtering layer is covered with a planarization layer.
11. The multispectral imager according to claim 1 , wherein the filtering layer is formed on the filter substrate.
12. The multispectral imager according to claim 1 , wherein the first interference filter and the second interference filter are part of an array of interference filters, and wherein the filtering layer is formed on the filter substrate with the array of interference filters interposed inbetween.