MULTIFUNCTIONAL OPTICAL SENSOR COMPRISING A PHOTODETECTORS MATRIX COUPLED TO A MICROLENSES MATRIX

• US 20070096010A1
• Filed: 09/19/2006
• Published: 05/03/2007
• Est. Priority Date: 09/19/2005
• Status: Active Grant

• Current Assignee: C.R.F. Societa Consortile Per Azioni
• Original Assignee: C.R.F. Societa Consortile Per Azioni
• Inventors: Repetto, Piermario, Capello, Davide, Liotti, Luca, Carvignese, Cosimo, Finizio, Roberto, Pallaro, Nereo
• Granted Patent: US 7,518,099 B2
• Time in Patent Office: Days
• US Class Current: 250/208.1
• CPC Class Codes: B60R 1/00 Optical viewing arrangements; Real-time viewing arrangements for drivers or passengers using optical image capturing systems, e.g. cameras or video systems specially adapted for use in or on vehicles
• CPC Class Codes: B60R 2300/108 using 'non-standard' camera systems, e.g. camera sensor used for additional purposes i.a. rain sensor, camera sensor split in multiple image areas
• CPC Class Codes: B60R 2300/305 merging camera image with lines or icons
• CPC Class Codes: B60R 2300/8053 for bad weather conditions or night vision
• CPC Class Codes: B60R 2300/8093 for obstacle warning
• CPC Class Codes: G01J 1/0407 Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings
• CPC Class Codes: G01J 1/0411 using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H04N 23/957 Light-field or plenoptic cameras or camera modules
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

Multifunctional optical sensor, comprising a matrix of photodetectors of the CCD or CMOS type, having a sensitive area divided into sub-areas, each of which, individually or combined with others, is dedicated to a specific function of monitoring the scene or measuring environmental parameters. The optical sensor comprises a matrix of microlenses, each of which is set to focus the radiation coming from a portion of solid angle on the associated photodetector or cluster of mutually contiguous photodetectors. Each function is associated to a single microlens or to a single subgroup of mutually contiguous microlenses or to multiple, not mutually contiguous microlenses or to multiple, not mutually contiguous subgroups of microlenses. The angular separation between the central directions of the portions of solid angle subtended by adjacent photodetectors or adjacent clusters of photodetectors is not constant within the matrix.

Claims

1. A multifunctional optical sensor, comprising a matrix of photodetectors of the CCD or CMOS type, having a sensitive area divided into sub-areas, each of which, individually or combined with others, is dedicated to a specific function of monitoring the scene or measuring environmental parameters,

said optical sensor comprising a matrix of microlenses, each microlens being set to focus the radiation coming from a portion of solid angle on the associated photodetector or cluster of mutually contiguous photodetectors,

each function being associated to a single microlens or to a single subgroup of mutually contiguous microlenses or to multiple, not mutually contiguous microlenses or to not mutually contiguous subgroups of microlenses,

the contiguous photodetectors able to be associated to a function defining a sub-area (ROI or Region Of Interest)

the angular separation between the central directions of the portions of solid angle subtended by adjacent photodetectors or adjacent clusters of photodetectors being not constant within the matrix.

2. Optical sensor as claimed in claim 1, wherein the microlenses are mutually identical and are positioned at each photodetector or cluster of photodetectors, a diaphragm being provided, positioned between the photodetectors matrix and the microlenses matrix, said diaphragm enabling to select for each photodetector or cluster of photodetectors a portion of the solid angle subtended by each microlens.

3. Optical sensor as claimed in claim 1, wherein the microlenses are off-axis and each of them is centred on a respective photodetector or cluster of photodetectors, each microlens being designed in such a way as to select for each photodetector or cluster of photodetectors a portion of the solid angle subtended by each microlens.

4. Optical sensor as claimed in claim 1, wherein said sensor comprises a matrix of micro-objectives each of which is constituted by at least two microlenses, each of said micro-objectives being associated to a respective photodetector or group of photodetectors and related diaphragms.

5. Optical sensor as claimed in claim 4, wherein said diaphragm is replaced by a subgroup of photodetectors having equal or smaller dimensions than the diaphragm in order to select the central direction of the field of view subtended by the microlens.

6. Optical sensor as claimed in claim 2, wherein a separation baffle is present between contiguous microlenses.

7. Optical sensor as claimed in claim 3, wherein a diaphragm positioned between the microlenses matrix and the photodetector or cluster of photodetectors associated to the respective microlens.

8. Optical sensor as claimed in claim 3, wherein said microlenses are designed with optical solutions of the refractive kind, with total internal reflection, reflexive or a combination of the above.

9. Optical sensor as claimed in claim 1, wherein adjacent sub-areas are dedicated to different functions, in which the fields of view of the sub-areas are different.

10. Optical sensor as claimed in claim 1, wherein at least one of the functions integrated on the photodetectors matrix is associated to a single microlenses subgroup which subtends a solid angle FOV, and contiguous photodetectors or photodetector clusters, associated to the microlenses subgroup, which do not always have mutually adjacent IFOVs.

11. Optical sensor as claimed in claim 1, wherein the microlenses of at least one subgroup have different and mutually contiguous fields of view, in such a way as to obtain a different resolution inside the global field of view of said subgroup.

12. Optical sensor as claimed in claim 1, wherein the microlenses of at least one subgroup have equal, but not contiguous fields of view, in such a way as to sample in non continuous fashion the global field of view of the microlenses subgroup.

13. Optical sensor as claimed in claim 1, wherein there are photodetectors used solely for separating the adjacent sub-areas of the sensitive area of the photodetectors matrix.

14. Optical sensor as claimed in claim 1, wherein said microlenses are constituted by a gradient index (GRIN) material.

15. Optical sensor as claimed in claim 1, wherein the microlenses of at least one sub-group have on their surface oriented towards the photodetectors matrix a selective interferential optical coating operating as a filter to transmit only the wavelengths of interest.

16. Optical sensor as claimed in claim 1, wherein the photodetectors matrix is in CCD or CMOS technology, standard or with parallel architecture provided with pre-processing at the photodetector level.

17. Optical sensor as claimed in claim 1, wherein at least one sub-area of the matrix having mxn photodetectors is coupled to a subgroup of microlenses in such a way that adjacent portions of the objects plane are subtended in the image plane by photodetectors that are not mutually contiguous.

18. Optical sensor as claimed in claim 1, wherein a sub-area having mxn=t photodetectors which subtends a field of view of x horizontal degrees and y vertical degrees can be remapped on the matrix as sub-area pxq=t photodetectors so that each photodetector has a field of view of x/m horizontal degrees and y/n vertical degrees and central direction such as to cover a portion of the global field of view of x horizontal degrees and y vertical degrees.

19. Optical sensor as claimed in claim 1, comprising at least one subgroup of microlenses dedicated to the frontal scene monitoring function, in which in the microlenses belonging to said subgroup the angular separation between the central directions subtended by the adjacent microlenses is not constant and the individual fields of view subtended by the microlenses are not constant, in such a way as to vary the resolution in specific areas of interest of the scene.

20. Optical sensor as claimed in claim 1, comprising at least one subgroup of microlenses dedicated to the frontal scene monitoring function, in which in the microlenses belonging to said subgroup the angular separation between the central directions subtended by the adjacent microlenses is not constant and the individual fields of view subtended by the microlenses are constant, in such a way as to sample in non continuous fashion the portion of the scene for which a lower resolution is required.

21. Optical sensor as claimed in claim 1, wherein the parameters of the microlenses associated to each photodetector or subgroup of photodetectors are optimised in such a way as to obtain an optical pre-processing.

22. Optical sensor as claimed in claim 1, wherein in said photodetectors matrix are defined k groups of j photodetectors, each group able to create the image of the same portion of scene or of different portions of scene, on said groups being positioned diaphragms with different shapes so that when a group creates the image of the portion of scene that matches the shape of the diaphragm the signal is strongest.

23. Optical sensor as claimed in claim 1, wherein in said photodetectors matrix are defined k groups of photodetectors positioned horizontally, said groups being coupled with the respective microlenses able to create the image of k different portions of the scene in such a way as to obtain an optical pre-processing.

24. An optical sensor as claimed in claim 1, comprising at least one photodetector serving the function of measuring environmental illumination, positioned in any point of the sensitive area of the photodetectors matrix, said at least one photodetector being associated to a central microlens surrounded by a certain number of microlenses, in such a way as to obtain information both about the intensity of environmental lighting by means of said central microlens, and on the intensity and direction of solar irradiation by means of said lateral microlenses.

25. Optical sensor as claimed in claim 24, wherein at least one of said lateral microlenses is oriented towards the dashboard of the vehicle to measure the solar irradiation directed thereon.

26. Optical sensor as claimed in claim 1, wherein the sub-area of the photodetectors matrix destined to perform the frontal monitoring function has the shape of a trapezoid.

27. Optical sensor as claimed in claim 1, wherein for the rain function said microlenses have their optical axis parallel to the road plane and such focal distance as to compensate for the curvature of the windshield.

28. Optical sensor as claimed in claim 1, wherein for the occupant monitoring function in said photodetectors matrix are dedicated one or more pixels coupled to a prismatic or wave guide system able to receive the image positioned to the rear of said photodetectors matrix.

29. Optical sensor as claimed in claim 1, wherein for the blind angle monitoring function in said photodetectors matrix are dedicated one or more subgroups of photodetectors, said subgroups of photodetectors having different fields of view in order to cover different directions with different resolutions.