Method and apparatus for characterizing an object

Patent metadata

Field	Value
Publication number	US-11480515-B2
Application number	US-202016899649-A
Country	US
Kind code	B2
Filing date	Jun 12, 2020
Priority date	Jun 12, 2020
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

An optical method of characterizing an object comprises providing an object to be characterized, the object having at least one nanoscale feature; illuminating the object with coherent plane wave optical radiation having a wavelength larger than the nanoscale feature; capturing a diffraction intensity pattern of the radiation which is scattered by the object; supplying the diffraction intensity pattern to a neural network trained with a training set of diffraction intensity patterns corresponding to other objects with a same nanoscale feature as the object to be characterized, the neural network configured to recover information about the object from the diffraction intensity pattern; and making a characterization of the object based on the recovered information.

First claim

The invention claimed is:

1. An optical method of characterizing an object, comprising
providing an object to be characterized, the object having at least one nanoscale feature;
illuminating the object with coherent plane wave optical radiation having a wavelength larger than the nanoscale feature;
capturing a diffraction intensity pattern of the radiation which is scattered by the object;
supplying the diffraction intensity pattern to a neural network trained with a training set of diffraction intensity patterns corresponding to other objects with a same nanoscale feature as the object to be characterized, the neural network configured to recover information about the object from the diffraction intensity pattern; and
making a characterization of the object based on the recovered information.

2. An optical method according to claim 1 , comprising capturing the diffraction intensity pattern in a plane lying in the optical far-field from the object.

3. An optical method according to claim 1 , comprising capturing the diffraction intensity pattern in a plane spaced from the object by a distance in the range of one to ten times the wavelength of the radiation.

4. An optical method according to claim 1 , comprising capturing the diffraction intensity pattern in a plane lying in the optical near-field from the object.

5. An optical method according to claim 1 , wherein the illuminating the object comprises illuminating the object with coherent plane wave optical radiation at two or more wavelengths larger than the nanoscale feature, such that the diffraction intensity pattern includes scattered radiation at the two or more wavelengths.

6. An optical method according to claim 1 , comprising capturing diffraction intensity patterns in two or more planes spaced from the object by different distances, supplying each diffraction intensity pattern to the neural network to recover information about the object, and making the characterization of the object based on an average of the recovered information from all the diffraction intensity patterns.

7. An optical method according to claim 1 , in which the training set comprises diffraction intensity patterns captured from real objects for which parameters of the at least one nanoscale feature are known.

8. An optical method according to claim 1 , in which the training set comprises computer-generated diffraction intensity patterns generated for objects for which parameters of the at least one nanoscale feature are predefined.

9. An optical method according to claim 1 , in which the recovered information comprises one or more dimensions of the nanoscale feature, the nanoscale feature being external or internal to the object, and the characterization of the object is an assignment of the one or more dimensions to the object.

10. An optical method according to claim 1 , in which the recovered information comprises a presence or absence of the nanoscale feature in or on the object, and the characterization of the object is an indication that the object does or does not include the nanoscale feature.

11. An optical method according to claim 10 , in which the recovered information further comprises a position of the nanoscale feature in or on the object, and the characterization of the object is an assignment of the position of the nanoscale feature to the object.

12. An optical method according to claim 1 , in which the object comprises a group of nanoscale items, the recovered information comprises a count value of nanoscale items in the group, and the characterization of the object is an assignment of the count value to the object.

13. An optical method according to claim 1 , in which the object comprises one or more nanoscale items, the recovered information comprises class or classes of the items, and the characterization of the object is an assignment of the class or classes to the object in order to classify the items in the object.

14. An optical method according to claim 1 , in which the characterization of the object is a complete or partial reconstruction of the object's appearance in two or three dimensions.

15. An apparatus for characterization of an object, comprising:
a source of coherent plane wave optical radiation;
a location at which an object to be characterized, and having at least one nanoscale feature smaller than a wavelength of the radiation, can be positioned in order to be illuminated with radiation from the source;
an optical detector configured to capture a diffraction intensity pattern of radiation scattered by an object at the location; and
a processor hosting a neural network and configured to supply captured diffraction intensity patterns from the optical detector to the neural network, the neural network having been trained with a training set of diffraction intensity patterns corresponding to other objects with a same nanoscale feature as the object to be characterized, the neural network being configured to recover information about an object at the location from a captured diffraction intensity pattern;
the processor operable to determine a characterization of the object based on the recovered information.

16. An apparatus according to claim 15 , wherein the recovered information comprises one or more dimensions of the nanoscale feature, and the characterization of the object is an assignment of the one or more dimensions to the object.

17. An apparatus according to claim 15 , in which the recovered information comprises a presence or absence of the nanoscale feature in or on the object, and the characterization of the object is an indication that the object does or does not include the nanoscale feature.

18. An optical method according to claim 15 , in which the object comprises a group of nanoscale items, the recovered information comprises a count value of nanoscale items in the group, and the characterization of the object is an assignment of the count value to the object.

19. A non-transitory computer storage medium storing software comprising a computer program configured to implement a neural network that has been trained with a training set of diffraction intensity patterns corresponding to objects with at least one common nanoscale feature having a known parameter value, the diffraction intensity patterns formed by coherent plane wave optical radiation at a wavelength larger than the nanoscale feature, the neural network configured to:
receive a diffraction intensity pattern of an object to be characterized, the object having the common nanoscale feature; and
recover a parameter value for the nanoscale feature in the object from the received diffraction intensity pattern.

20. A storage medium according to claim 19 , wherein the computer program is further configured to determine a characterization of the object to be characterized based on the recovered parameter value.

Assignees

• Univ Southampton
• Univ Nanyang Tech

Inventors

• Zheludev Nikolay Ivanovich
• Papasimakis Nikitas
• Ou Jun-Yu
• Pu Tanchao
• Kurdiumov Sergei
• Chan Eng Aik
• Rendón-Barraza Carolina

Classifications

• G03H2001/005

  in microscopy, e.g. digital holographic microscope [DHM] · CPC title

• G01N2015/1493

  Particle size · CPC title

• G01N15/1434 Primary

  Optical arrangements · CPC title

• G01N2015/1497

  Particle shape · CPC title

• G01N15/1429

  Signal processing · CPC title