Plenoptic zoom with optimised range
An optical system includes an objective of the zoom type and a depth-estimating optical detecting unit, the depth-estimating optical detecting unit including a matrix array of micro-lenses and a matrix-array detector, the matrix array of micro-lenses being arranged so that the image of the focal plane of the zoom is focused by the matrix array of micro-lenses on the plane of the matrix-array detector. The optical system calculates, for a first focal length of the zoom and for a given object, the estimated distance of this object and the measurement uncertainty in this estimation, depending on the first focal length and the estimated distance and, this estimated distance being known, optimizes by allowing at least one second focal length of the zoom to which a lower measurement uncertainty in this estimation corresponds to be determined.
1. An optical system including an objective of a zoom type and a depth-estimating optical detecting unit, said depth-estimating optical detecting unit including a matrix array of micro-lenses and a matrix-array detector, the matrix array of micro-lenses being arranged so that an image of a focal plane is focused by the matrix array of micro-lenses on the plane of the matrix-array detector,
wherein said optical system is configured to calculate at least:
for a first focal length of a first zoom and for a given object, the distance of the object being in the field-depth interval of the first focal length, a first estimated distance of this object and a measurement uncertainty in this estimation, the measurement uncertainty being a distance as a function of said first focal length and said first estimated distance, and
for a second focal length of a second zoom and for the same given object, the distance of the object being in the field-depth interval of the second focal length, a second estimated distance of this object and a second measurement uncertainty in this second estimation, the second measurement uncertainty being a second distance as a function of said second focal length and said second estimated distance of the object, a best estimated distance being the one that gives the smallest measurement uncertainty, and
wherein the image of the focal plane is focused by the matrix array of micro-lenses on the plane of the matrix-array detector based on the best estimated distance.
2. The optical system as claimed in claim 1 , wherein the optical system is further configured to calculate a loop of iterations allowing an optimal focal length to which a minimum measurement uncertainty in said estimation corresponds to be determined, each iteration including at least one change of focal length, and the estimated distance corresponding to a new focal length and the measurement uncertainty in this estimation to be calculated.
3. The optical system as claimed in claim 2 , wherein the loop of iterations is carried out in a constant zoom focal plane.
4. The optical system as claimed in claim 2 , wherein the loop of iterations is carried out in a variable zoom focal plane.
5. The optical system as claimed in claim 2 , wherein the loop of iterations is carried out at constant zoom aperture.
6. The optical system as claimed in claim 2 , wherein the loop of iterations is carried out at variable zoom aperture.
7. The optical system as claimed in claim 1 , wherein the first and the second zooms are continuously variable focal lengths.
8. The optical system as claimed in claim 1 , wherein the first and the second zooms are multi-focal objectives.
9. The optical system as claimed in claim 1 , wherein the depth-estimating optical detecting unit is an infrared detecting unit.