Method of enabling spatially varying auto focusing of objects and an image capturing system thereof

Patent metadata

Field	Value
Publication number	US-10521695-B2
Application number	US-201615078314-A
Country	US
Kind code	B2
Filing date	Mar 23, 2016
Priority date	Mar 25, 2015
Publication date	Dec 31, 2019
Grant date	Dec 31, 2019

Abstract

The present inventive concepts discloses methods, apparatuses, and/or systems for enabling spatially varying auto focusing of one or more objects using an image capturing system. The methods, apparatuses, and/or systems may include focusing objects in a region of interest using lenses, enabling spatially varying auto focusing of objects in the region of interest using a spatial light modulators (SLM), which are out of focus in the region of interest, and capturing the focused and the auto focused objects in the region of interest using a camera sensor.

First claim

What is claimed is:

1. A method of enabling spatially varying auto focusing of one or more objects using an image capturing system comprising:
focusing, using one or more lenses of the image capturing system, on one or more objects in a region of interest;
enabling spatially varying auto focusing of the one or more objects in the region of interest using at least two spatial light modulators (SLM), wherein at least one of the one or more objects are out of focus when viewing the region of interest; and
capturing the focused and the auto focused objects in the region of interest using a camera sensor, wherein
the enabling spatially varying auto focusing of one or more objects in the region of interest includes removing an aberration from the captured image using the at least two SLMs,
the removing including,
positioning a first SLM of the at least two SLMs and a second SLM of the at least two SLMs between the lens and the camera sensor,
changing a focal length of the second SLM by providing a control signal to the second SLM to enable auto focus, and
modifying a phase profile of the first SLM based on feedback received from the camera sensor to further improve the image corresponding to encoding of an image with Zernike polynomials with increasing orders; and

storing the modified phase profile of the first SLM in a memory of the image capturing device;
the removing further including,
determining whether the region of interest has been selected,
dividing a field of view of the image capturing system into one or more desired regions of interest, if the region of interest has not been selected,
applying an aberration correction to the first SLM that corresponds to the regions of interest,
capturing an image of each of the regions of interest, and
forming a composite image by combining the captured images of each of the regions of interest.

2. The method as claimed in claim 1 , wherein at least one SLM of the at least two SLMs includes one or more segments.

3. The method as claimed in claim 2 , further comprising:
applying a control signal to the at least one SLM of the at least two SLMs and each segment of the at least one SLM; and
modifying refractive indexes of each of the segments of the at least one SLM and phase of light beam incident on each of the segments of the at least one SLM in accordance with the applied control signal.

4. The method as claimed in claim 1 , further comprising:
modifying a control signal to provide quadratic variation in phase change across the at least two SLMs, wherein the phase change corresponds to a change in focal length of the at least two SLMs.

5. The method as claimed in claim 1 , wherein the enabling spatially varying auto focusing of the one or more objects in the region of interest using the at least two SLMs includes:
obtaining a Z map of a die of a wafer to be inspected; and
calibrating focal lengths of the at least two SLMs in accordance with a corresponding control signal based on the Z map of the die for enabling auto focusing of the die of a wafer to be inspected on the camera sensor; and
dynamically varying in real time the control signal so as to correspond each segment of the at least two SLMs with the die below the camera sensor, by providing different focal lengths using values from the calibration and the Z map.

6. The method as claimed in claim 5 , wherein the obtaining the Z map of the die of the wafer to be inspected includes:
analyzing a cross section of the die to be inspected to obtain a Z height of the die; and
quantizing the Z height of the die based on a desired acceptance circle of confusion.

7. The method as claimed in claim 5 , wherein the calibrating focal lengths of the at least two SLMs includes:
locating the die having a Z height at a desired distance in front of a camera system for calibrating the focal lengths of the at least two SLMs;
modifying the control signal corresponding to each segment of the at least two SLMs to bring about a corresponding phase change in each of the segments of the at least two SLMs to capture an image with a desired clarity on the camera sensor; and
storing the modified control signal and the corresponding phase change of each of the segments of the at least two SLMs corresponding to the Z map of the die in a memory of the image capturing system.

8. The method as claimed in claim 1 , wherein the enabling spatially varying auto focusing of the one or more objects in the region of interest using the at least two SLMs includes:
enabling auto focusing for one or more foveation spots;
selecting the one or more foveation spots by communicating at least one of a shift in gaze information and change in pointing device information to the image capturing system upon identifying the object in focus; and
applying the control signal to the one or more segments of the at least two SLMs for auto focusing the selected foveation spot.

9. An image capturing method, comprising:
modulating, using a plurality of spatial light modulators (SLMs), light reflected from at least one object located on a semiconductor wafer in accordance with a real-time modulation command, each of the SLMs including a plurality of individually addressable segments;
capturing, using an image sensor, an image output by the SLMs; and
transmitting, using at least one processor, the real-time modulation command to the plurality of SLMs based on the captured image, wherein
the modulating includes enabling spatially varying auto focusing of one or more objects in a region of interest,
the enabling includes removing an aberration from the captured image using at least two SLMs of the plurality of SLMs,
the removing including,
positioning a first SLM of the at least two SLMs and a second SLM of the at least two SLMs between the lens and the image sensor,
changing a focal length of the second SLM by providing a control signal to the second SLM to enable auto focus, and
modifying a phase profile of the first SLM based on feedback received from the image sensor to further improve the image corresponding to encoding of an image with Zernike polynomials with increasing orders; and

storing the modified phase profile of the first SLM in a memory of the image capturing device;
the removing further including,
determining whether the region of interest has been selected,
dividing a field of view into one or more desired regions of interest, if the region of interest has not been selected,
applying an aberration correction to the first SLM that corresponds to the regions of interest,
capturing an image of each of the regions of interest, and
forming a composite image by combining the captured images of each of the regions of interest.

10. The image capturing method as claimed in claim 9 , further comprising:
filtering, using an aperture mask, the reflected light prior to receipt by the SLMs;
generating, using the image sensor, one or more partial images from the filtered light;
processing, using the at least one processor, the generated partial images; and
providing, using the at least one processor, feedback to the SLMs to modify focal lengths of the SLMs in accordance with the generated partial images.

11. The image capturing method as claimed in claim 9 , wherein the real-time modulation command includes instructions to configure the SLMs to adjust the phase of the reflected light passing through the SLMs.

12. The image capturing method as claimed in claim 9 , wherein the object is a calibration die including a plurality of physical features of different heights.

13. The image capturing method as claimed in claim 12 , wherein the transmitting inc

Assignees

• Samsung Electronics Co Ltd

Inventors

• Agashe Shashank Shrikant
• Kumar Gaurav

Classifications

• G06V10/762

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• G06F18/23

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• H04N17/002 Primary

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• G02B26/0816

  by means of one or more reflecting elements · CPC title

• H04N23/67

  Focus control based on electronic image sensor signals · CPC title