OBJECT INFORMATION ACQUIRING APPARATUS AND METHOD FOR CONTROLLING OBJECT INFORMATION ACQUIRING APPARATUS

• US 20140378811A1
• Filed: 06/13/2014
• Published: 12/25/2014
• Est. Priority Date: 06/21/2013
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Nanaumi, Ryuichi
• Granted Patent: US 9,737,216 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: G01N 2021/1706 in solids
• CPC Class Codes: G01N 2021/1708 with piezotransducers probes for investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves G01N29/24
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids

Abstract

An object information acquiring apparatus comprises a light irradiation unit that irradiates an object with pulsed light; a probe that converts an acoustic wave generated in the object due to first pulsed light into an acoustic wave signal; a photo-detection unit that converts second pulsed light propagated through the object into an optical signal; a frequency analysis unit that acquires a background optical coefficient with respect to the inside of the object on the basis of a predetermined frequency component of the optical signal; a light intensity acquiring unit that acquires a distribution of light intensity of the first pulsed light reaching the inside of the object using the background optical coefficient; and an information acquiring unit that acquires object information, using the acoustic wave signal and the distribution of light intensity.

Claims

1. An object information acquiring apparatus comprising:

a light irradiation unit that irradiates an object with pulsed light;

an acoustic wave probe configured to convert an acoustic wave generated in the object due to first pulsed light from the light irradiation unit into an acoustic wave signal;

a photo-detection unit configured to convert second pulsed light, which is from the light irradiation unit and propagated through the object, into an optical signal;

a frequency analysis unit configured to acquire a background optical coefficient with respect to the inside of the object on the basis of a predetermined frequency component of the optical signal;

a light intensity acquiring unit configured to acquire a distribution of light intensity that is a distribution of an intensity of the first pulsed light reaching the inside of the object on the basis of the background optical coefficient; and

an information acquiring unit configured to acquire object information on the inside of the object, on the basis of the acoustic wave signal and the distribution of light intensity.

2. The object information acquiring apparatus according to claim 1, wherein the frequency analysis unit is configured to acquire the background optical coefficient with respect to the inside of the object on the basis of an amplitude ratio of the predetermined frequency component to the second pulsed light and a phase difference between the predetermined frequency component and the second pulsed light.

3. The object information acquiring apparatus according to claim 1, wherein the predetermined frequency component is based on a frequency at which an amplitude or power of the frequency component configuring the second pulsed light is maximized.

4. The object information acquiring apparatus according to claim 1, wherein the predetermined frequency component is based on a frequency corresponding to a reciprocal of a pulse width of the second pulsed light.

5. The object information acquiring apparatus according to claim 1, wherein the photo-detection unit is configured to convert the second pulsed light propagated through the object at a plurality of different positions on the object into a plurality of optical signals.

6. The object information acquiring apparatus according to claim 5, wherein

the frequency analysis unit acquires a spatial distribution of the background optical coefficient, on the basis of the plurality of optical signals, and

the light intensity acquiring unit is configured to acquire the distribution of light intensity, on the basis of the spatial distribution of the background optical coefficient.

7. The object information acquiring apparatus according to claim 1, wherein

the light irradiation unit is configured to irradiate the object with the second pulsed light having a smaller irradiation area than that of the first light.

8. The object information acquiring apparatus according to claim 1, wherein the light irradiation unit comprises a plurality of optical members and is configured to switch from among the plurality of optical members to individually irradiate the first pulsed light and the second pulsed light.

9. The object information acquiring apparatus according to claim 1, wherein the light irradiation unit is configured to irradiate the object with the first pulsed light and the second pulsed light in parallel.

10. The object information acquiring apparatus according to claim 1, wherein a pulse width of the pulsed light is within a range of 10 nanoseconds to 650 nanoseconds at full width at half maximum.

11. The object information acquiring apparatus according to claim 1, wherein a pulse width of the pulsed light is within a range of 100 nanoseconds to 650 nanoseconds at full width at half maximum.

12. The object information acquiring apparatus according to claim 1, further comprising a reconstruction unit configured to acquire a distribution of initial sound pressure for the acoustic wave on the basis of the acoustic wave signal, and

the information acquiring unit is configured to acquire the object information on an inside of the object, on the basis of the distribution of initial sound pressure and the distribution of light intensity.

13. A method for acquiring information on an inside of an object,

the method comprising:

a step of irradiating the object with first pulsed light;

a step of converting an acoustic wave generated in the object due to the first pulsed light into an acoustic wave signal;

a step of irradiating the object with second pulsed light;

a step of converting the second pulsed light propagated through the object into an optical signal;

a step of acquiring a background optical coefficient with respect to the inside of the object on the basis of a predetermined frequency component of the optical signal;

a light intensity acquiring step of acquiring, on the basis of the background optical coefficient, a distribution of light intensity that is a distribution of an intensity of the first pulsed light reaching the inside of the object; and

a step of acquiring object information on the inside of the object, on the basis of the acoustic wave signal and the distribution of light intensity.

14. A non-transitory computer readable medium recording a computer program for causing a computer to perform the method according to claim 13.