Apparatus and method for irradiating a medium

Patent metadata

Field	Value
Publication number	US-10433734-B2
Application number	US-201514708062-A
Country	US
Kind code	B2
Filing date	May 8, 2015
Priority date	Sep 24, 2009
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A method for irradiating a medium includes irradiating the medium with an electromagnetic wave which is scattered in the medium and modulated in frequency at a position in the medium; obtaining information corresponding to an interference pattern generated by interference between the modulated electromagnetic wave and a reference wave; and generating a phase conjugate wave, based on the obtained information, which irradiates the medium.

First claim

What is claimed is:

1. An apparatus comprising:
a first irradiation unit configured to irradiate a medium with an incident wave;
an ultrasound device configured to focus an ultrasound wave onto a position in the medium such that the incident wave is modulated into a frequency-shifted wave at the position where the ultrasound wave is focused by the ultrasound device;
a first detection unit configured to obtain information corresponding to an interference pattern generated by interference between the frequency-shifted wave and a reference wave;
a second irradiation unit configured to irradiate the first detection unit with the reference wave, a frequency difference between the reference wave and the incident wave being exactly or approximately equal to a frequency of the ultrasound wave focused by the ultrasound device;
a generation unit configured to irradiate the medium with a phase conjugation wave of the frequency-shifted wave to irradiate the medium to retrace trajectory of the frequency-shifted wave to the position where the ultrasound wave is focused by the ultrasound device based on the information obtained by the first detection unit; and
a processing unit configured to control the generation unit,
a second control unit configured to control the ultrasound device,
wherein the first detection unit comprises an array sensor configured to detect the interference pattern,
wherein the generation unit comprises a spatial light modulator,
wherein the processing unit is configured set phase values of pixels included in the spatial light modulator based on the information corresponding to the interference pattern detected by the array sensor, and
wherein the spatial light modulator is configured to modulate light by the set phase values at the pixels included in the spatial light modulator to generate the phase conjugation wave of the frequency-shifted wave,
wherein the second control unit is configured to set the position by using information obtained from a modality such that the ultrasound device focuses the ultrasound wave onto the set position, the modality including X-ray, MRI, or ultrasound.

2. The apparatus according to claim 1 , further comprising:
a first photodetector arranged to monitor an intensity of the incident wave before being irradiated on the medium, and
a first control unit configured to control the first irradiation unit and the generation unit so that an intensity of the phase conjugation wave generated from the generation unit is different from an intensity of the incident wave generated from the first irradiation unit,
wherein the first control unit is configured to control the first irradiation unit based on an output of the first photodetector so that the intensity of the incident wave is kept below a predetermined exposure and is configured to control the generation unit so that the intensity of the phase conjugation wave is lower than the predetermined exposure.

3. The apparatus according to claim 2 , wherein the predetermined exposure is a maximum exposure.

4. The apparatus according to claim 1 , wherein the array sensor comprises a CCD sensor, a CMOS sensor, area sensors with an image intensifier, or EMCCD (Electron Multiplying CCD).

5. The apparatus according to claim 1 , further comprising a second detection unit configured to detect a signal output from the medium in response to irradiation of the phase conjugation wave.

6. The apparatus according to claim 1 , further comprising a second photodetector configured to detect a light signal output from the medium in response to irradiation of the phase conjugation wave.

7. The apparatus according to claim 1 , further comprising an ultrasound detector configured to detect a photoacoustic signal output from the medium in response to irradiation of the phase conjugation wave.

8. The apparatus according to claim 1 , wherein the ultrasound device is configured to detect a photoacoustic signal output from the medium in response to irradiation of the phase conjugation wave.

9. The apparatus according to claim 1 , further comprising an image formation unit configured to form an image using a signal output from the medium in response to irradiation of the phase conjugation wave.

10. The apparatus according to claim 1 , wherein the first irradiation unit and the second irradiation unit include a common electromagnetic wave source.

11. The apparatus according to claim 1 , wherein the common electromagnetic wave source is configured to generate an electromagnetic wave whose wavelength is not less than 380 nm and not more than 2500 nm.

12. The apparatus according to claim 1 , further comprising a filter between the medium and the first detection unit, wherein
the filter reduces by a first amount an intensity of the first electromagnetic wave transmitted from the medium to the first detection unit;
the filter reduces by a second amount an intensity of the frequency-shifted electromagnetic wave transmitted from the medium to the first detection unit; and
the first amount is greater than the second amount.

13. The apparatus according to claim 1 , wherein the first detection unit is configured to obtain the information corresponding to the interference pattern by a phase-shifting digital holography technique, the frequency difference between the reference wave and the incident wave being exactly or approximately equal to a sum of a frequency of the ultrasound wave focus by the ultrasound device and a value which is a frame rate of the first detection unit divided by a number of measurements for a phase shifting method.

14. The apparatus according to claim 1 , the first irradiation unit includes a modulator configured to modulate a frequency of the incident wave.

15. The apparatus according to claim 1 , wherein the second irradiation unit includes a modulator configured to modulate a frequency of the reference wave.

16. The apparatus according to claim 1 , wherein the spatial light modulator comprises a liquid crystal on silicon.

17. The apparatus according to claim 1 , wherein,
in a case that the array sensor has a larger number of pixels compared to the spatial light modulator, the array sensor is configured to perform binning so that the number of pixels between the array sensor and the spatial light modulator is equal and those pixels correspond with each other.

18. The apparatus according to claim 1 , wherein the second control unit is configured to set a first position and a second position that is deeper than the first position in the medium such that, after focusing of the reconstructed light on the first position, the reconstructed light is focused on the second position.

19. The apparatus according to claim 1 , wherein the second control unit is configured to set a first size and a second size that is smaller than the first size of a focus region of the ultrasound wave such that, after focusing of the reconstructed light on the focus region of the first size, the reconstructed light is focused on the focus region of the second size.

Assignees

• Canon Kk

Inventors

• Masumura Takahiro

Classifications

• G01N21/1717 Primary

  with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance · CPC title

• G03H2222/10

  Spectral composition · CPC title

• G01N21/4795

  spatially resolved investigating of object in scattering medium (in vivo A61B) · CPC title

• A61B5/0097 Primary

  by applying acoustic waves and detecting light, i.e. acousto-optic measurements · CPC title

• G01N2021/1727

  Magnetomodulation · CPC title