Apparatus and method for irradiating a medium

• US 8,954,130 B2
• Filed: 12/15/2011
• Issued: 02/10/2015
• Est. Priority Date: 12/17/2010
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Masumura, Takahiro
• Primary Examiner(s): KISH, JAMES M
• Application Number:
  US13/327,581
• Publication Number:
  US 20120182561A1
• Time in Patent Office: 1,153 Days
• Field of Search: 600/407, 600/437, 600/472, 600/476, 356/479, 356/497
• US Class Current: 600/407
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: G01N 2021/1729 Piezomodulation
• CPC Class Codes: G01N 2021/1787 Tomographic, i.e. computerised reconstruction from projective measurements
• CPC Class Codes: G01N 2021/4186 Phase modulation imaging
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids
• CPC Class Codes: G01N 21/1717 with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
• CPC Class Codes: G01N 21/453 Holographic interferometry for dimensional measurements G01B9/021 - G01B9/029
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G01N 21/6456 Spatial resolved fluorescence measurements; Imaging
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G03H 1/0443 Digital holography, i.e. recording holograms with digital recording means holobject computation G03H1/0866
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 2001/0463 Frequency heterodyne, i.e. one beam is frequency shifted
• CPC Class Codes: G03H 2001/0467 Gated recording using pulsed or low coherence light source, e.g. light in flight, first arriving light

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.

Claims

1. An apparatus comprising:

a light source configured to emit an electromagnetic wave;

an optical system configured to irradiate a medium with the electromagnetic wave emitted from the light source;

an ultrasound system configured to focus a plurality of ultrasound waves, wherein each of the plurality of ultrasound waves is focused onto a different one of a plurality of positions in the medium, such that, by traveling to the plurality of positions, the electromagnetic wave is modulated into a frequency-shifted electromagnetic wave by a sum of frequencies of the plurality of ultrasound waves;

a detector configured to obtain information about an interference pattern generated by interference between the frequency-shifted electromagnetic wave and a reference wave;

a modulator configured to modulate at least one of the electromagnetic wave to irradiate the medium and the reference wave to irradiate the detector, such that a frequency difference between the electromagnetic wave to irradiate the medium and the reference wave to irradiate the detector equals to or substantially equals to the sum of the frequencies of the plurality of ultrasound waves, such that the interference between the frequency-shifted electromagnetic wave and the reference wave is caused; and

a generator configured to irradiate the medium with a phase conjugate wave of the frequency-shifted electromagnetic wave based on the obtained information.

2. The apparatus according to claim 1, wherein the generator includes a spatial light modulator.

3. The apparatus according to claim 1,

wherein the modulator is configured to modulate a frequency of the reference wave to irradiate the detector by the sum of the frequencies.

4. The apparatus according to claim 1,

wherein the modulator is configured to modulate a frequency of the electromagnetic wave to irradiate the medium by a negative value of the sum of the frequencies.

5. The apparatus according to claim 1,

wherein the modulator is configured to modulate a frequency of the electromagnetic wave to irradiate the medium by the sum of the frequencies.

6. The apparatus according to claim 1, wherein the ultrasound system is configured to focus the plurality of ultrasound waves onto the plurality of positions along an incident direction of the electromagnetic wave to the medium.

7. The apparatus according to claim 1, wherein the ultrasound system includes a plurality of ultrasound devices, each of the plurality of ultrasound devices being configured to emit different one of the plurality of ultrasound waves.

8. The apparatus according to claim 1, further comprising an image generating unit, wherein

the ultrasound system is configured to detect a signal output from the medium in response to irradiation with the phase conjugate wave, and

the image generating unit is configured to generate an image using the signal detected by the ultrasound system.

9. The apparatus according to claim 1, further comprising:

an another ultrasound system different from the ultrasound system, configured to detect a signal output from the medium in response to irradiation with the phase conjugate wave; and

an image generating unit configured to generate an image using the signal detected by said another ultrasound system.

10. The apparatus according to claim 1, further comprising:

an electromagnetic wave detector configured to detect a signal output from the medium in response to irradiation with the phase conjugate wave; and

an image generating unit configured to generate an image using the signal detected by the electromagnetic wave detector.

11. The apparatus according to claim 1, wherein the optical system includes a beam splitter configured to split the electromagnetic wave emitted from the light source into the reference wave to irradiate the electromagnetic wave detector and the electromagnetic wave to irradiate the medium.

12. The apparatus according to claim 1, wherein the light source is configured to emit the electromagnetic wave whose frequency is between 380 nm to 2500 nm.

13. The apparatus according to claim 1, wherein the detector includes a light sensor.

14. The apparatus according to claim 1, wherein

the detector includes a hologram material configured to record the information about the interference pattern, and

the generator includes the hologram material configured to emit the phase conjugation wave based on the recorded information.

15. The apparatus according to claim 1, wherein

the frequencies of the plurality of ultrasound waves are different from each other.

16. A method for irradiating a medium, the method comprising:

irradiating a medium with an electromagnetic wave;

focusing a plurality of ultrasound waves, wherein each of the plurality of ultrasound waves is focused onto a different one of a plurality of positions in the medium,

modulating the electromagnetic wave, by traveling to the plurality of positions, into a frequency-shifted electromagnetic wave by a sum of frequencies of the plurality of ultrasound waves;

modulating at least one of the electromagnetic wave to irradiate the medium and a reference wave such that a frequency difference between the electromagnetic wave to irradiate the medium and the reference wave equals to or substantially equals to the sum of the frequencies of the plurality of ultrasound waves, such that the interference between the frequency-shifted electromagnetic wave and the reference wave is caused; and

obtaining information about an interference pattern generated by interference between the frequency-shifted electromagnetic wave and the reference wave; and

irradiating the medium with a phase conjugate wave of the frequency-shifted electromagnetic wave based on the obtained information.

17. The method according to claim 16,

wherein the modulating at least one of the electromagnetic wave to irradiate the medium and the reference wave includes modulating a frequency of the reference wave to irradiate the electromagnetic wave detector by the sum of the frequencies.

18. The method according to claim 16,

wherein the modulating at least one of the electromagnetic wave to irradiate the medium and the reference wave includes modulating a frequency of the electromagnetic wave to irradiate the medium by a negative value of the sum of the frequencies.

19. The method according to claim 16,

wherein the modulating at least one of the electromagnetic wave to irradiate the medium and the reference wave includes modulating a frequency of the electromagnetic wave to irradiate the medium by the sum of the frequencies.

20. The method according to claim 16, further comprising:

detecting a signal output from the medium in response to irradiation with the phase conjugate wave; and

generating an image using the signal detected in the detecting.

21. The method according to claim 16, wherein,

the frequencies of the plurality of ultrasound waves are different from each other.