Device and method for extended depth of field imaging
A device and method for extended depth of field imaging are provided. The device includes an optical device configured to simultaneously form intermediate images of an object at different distances with a blur effect on at least parts of images of the object, the optical device comprising at least one optical element and at least two pupil zones formed to provide a predetermined distribution of optical powers and aberrations within each of the at least two pupil zones, based on which point spread function is formed, defined by a curve with minimized side peaks compared to a central peak in a given range of object distances, each of the at least two pupil zones corresponding to a respective given range of object distances and a respective given range of field angles, a sensor configured to simultaneously register the intermediate images formed by the optical device from different object distances and at different field angles, and an image processor communicatively connected to the sensor and the optical device, wherein the image processor is configured to process the intermediate images of the object with the blur effect on at least parts of the images of the object registered by the sensor, the intermediate images being processed based on an obtained point spread function over the given range of object distances and field angles, and reconstruct resulting images without the blur effect at output regardless of object distances.
1 . A device for extended depth of field imaging, the device comprising:
an optical device configured to simultaneously form intermediate images of an object at different distances with a blur effect on at least parts of images of the object, the optical device comprising at least one optical element and at least two pupil zones formed to provide a predetermined distribution of optical powers and aberrations within each of the at least two pupil zones, based on which a point spread function is formed, defined by a curve with minimized side peaks compared to a central peak in a given range of object distances, each of the at least two pupil zones corresponding to a respective given range of object distances and a respective given range of field angles, wherein each of the pupil zones (PZ 1 , PZ 2 ) is divided into subzones, each subzone having its own focus and beam;
a sensor configured to simultaneously register the intermediate images formed by the optical device from different object distances and at different field angles; and
an image processor communicatively connected to the sensor and the optical device,
wherein the image processor is configured to:
process the intermediate images of the object with the blur effect on at least parts of the images of the object registered by the sensor, the intermediate images being processed based on an obtained point spread function over the given range of object distances and field angles, and
reconstruct resulting images without the blur effect at output regardless of object distances, and
wherein the minimized side peaks of the point spread function, formed by the optical device, do not exceed 10% of the central peak in the given range of object distances.
2 . The device of claim 1 , wherein the given range of object distances is from 400 millimeters (mm) to 5000 mm.
3 . The device of claim 1 , wherein the given range of field angles is from −40 to +40 degrees.
4 . The device of claim 1 , wherein the optical device is further configured to form an invariant point spread function independent of an object distance over the given range of object distances.
5 . The device of claim 1 , wherein the optical device is further configured to form an invariant point spread function independent of a field angle.
6 . The device of claim 1 , wherein the optical device is further configured to form an invariant point spread function independent of a field angle and an object distance.
7 . The device of claim 1 , wherein the optical device is further configured to form a uniform modulation transfer function (MTF) independent of an object distance.
8 . The device of claim 1 , wherein the optical device is further configured to simultaneously form intermediate images of the object at different distances with the blur effect on an entire image of the object.
9 . The device of claim 1 , wherein the at least one optical element comprises at least one of a lens with different surface profiles, a composite lens, a diffractive optical element, a holographic optical element, a polarizing element, or an amplitude-phase mask.
10 . The device of claim 9 ,
wherein optical elements of the optical device comprise, arranged along an optical axis from an object side toward an image surface, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens,
wherein the first lens has a positive refractive power, with a surface facing the object side having a convex shape and a surface facing an image side having a concave shape,;
wherein the second lens has a negative refractive power and with both a surface facing the object side and a surface facing the image side having the concave shape,;
wherein the third lens has a positive refractive power,
wherein the fourth lens has a meniscus shape, and
wherein each of the fifth and sixth lenses has the meniscus shape near the optical axis, with a surface facing the object side having the convex shape near the optical axis and a surface facing the image side having the concave shape near the optical axis.
11 . The device of claim 1 , further comprising:
a shutter disposed in a plane of an aperture diaphragm or disposed in an imaging device plane conjugate with the shutter,
wherein the shutter is configured to control an opening or closing of a given number of pupil zones.
12 . The device of claim 1 , wherein the sensor is a matrix photodetector.
13 . The device of claim 12 ,
wherein the matrix photodetector is configured to detect electromagnetic radiation in a range of 0.4-0.7 micrometers (μm), and
wherein a sensor pixel size is from 0.7 μm to 1.5 μm.
14 . The device of claim 1 , wherein the image processor is further configured to:
process the intermediate images of the object and reconstruct resulting images at output based on at least one of a convolutional neural network or Wiener filter, parameters of which are predetermined based on design parameters of the optical device and the sensor.