# US 2017/0254784 A1 · Photoacoustic microscope and photoacoustic signal detection method

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- Number: US 2017/0254784 A1
- Document ID: US20170254784A1
- Status: Published application
- Kind: A1
- Application number: 15/603,857
- Filed: 2017-05-24
- Published: 2017-09-07
- Earliest claimed: 2014-11-28
- Assignees: Olympus Corporation
- Applicants: Olympus Corporation
- Inventors: Yoshiaki MURAYAMA
- Web page: https://patentgrep.com/patent/US20170254784A1

## CPC

- 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)}
- G01N 21/1702: {with opto-acoustic detection, e.g. for gases or analysing solids}
- G01N 29/0681: {by acoustic microscopy, e.g. scanning acoustic microscopy}
- G01N 29/11: by measuring attenuation of acoustic waves
- G01N 29/44: Processing the detected response signal {, e.g. electronic circuits specially adapted therefor (digital signal processing per se G06F17/00)}
- G01N 29/48: by amplitude comparison
- G02B 21/0036: {Scanning details, e.g. scanning stages}
- G02B 21/06: Means for illuminating specimens
- G02B 21/368: {details of associated display arrangements, e.g. mounting of LCD monitor}
- G01N 2291/02466: Biological material, e.g. blood
- G01N 2291/26: Scanned objects
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A photoacoustic microscope includes: a light source which generates pulse light; a focusing optical system which focuses the pulse light emitted from the light source and irradiate a sample with the focused pulse light; a photoacoustic signal detection unit which detects an acoustic signal generated from the sample through irradiation of the pulse light; an image signal formation unit which forms an image signal of the sample based on the acoustic signal; an information unit having information representing a relation between intensity of the pulse light entering the sample and intensity of the acoustic signal generated from the sample; and a pulse light intensity changing unit which changes intensity of the pulse light from the light source based on the information.

## Claims

### Claim 1

A photoacoustic microscope, comprising:
a light source which generates pulse light;
a focusing optical system which focuses the pulse light emitted from the light source and irradiate a sample with the focused pulse light;
a photoacoustic signal detection unit which detects an acoustic signal generated from the sample through irradiation of the pulse light;
an image signal formation unit which forms an image signal of the sample based on the acoustic signal;
an information unit having information representing a relation between intensity of the pulse light entering the sample and intensity of the acoustic signal generated from the sample; and
a pulse light intensity changing unit which changes intensity of the pulse light from the light source based on the information.

### Claim 2 (depends on 1)

The photoacoustic microscope according to claim 1, further comprising a display unit which displays the information included in the information unit.

### Claim 3 (depends on 1)

The photoacoustic microscope according to claim 1, wherein the information unit comprises an information generation unit which generates information representing a relation between the intensity of the pulse light entering the sample and the intensity of the acoustic signal generated from the sample.

### Claim 4 (depends on 1)

The photoacoustic microscope according to claim 1, wherein the information unit comprises an information storage unit which stores therein information representing a relation between the intensity of the pulse light entering the sample and intensity of the acoustic signal generated from the sample.

### Claim 5 (depends on 3)

The photoacoustic microscope according to claim 3, the information generation unit includes a threshold calculation unit which calculates, based on the information, as a threshold, pulse light intensity with which the intensity of the acoustic signal relative to the intensity of the pulse light starts to increase.

### Claim 6 (depends on 4)

The photoacoustic microscope according to claim 4, wherein the information storage unit stores therein, as a threshold, pulse light intensity with which the intensity of the acoustic signal relative to the intensity of the pulse light starts to increase.

### Claim 7 (depends on 5)

The photoacoustic microscope according to claim 5, further comprising a pulse light intensity changing unit which changes, based on the threshold calculated by the threshold calculation unit, the intensity of the pulse light from the light source to be equal to or more than the threshold.

### Claim 8 (depends on 7)

The photoacoustic microscope according to claim 7, wherein the pulse light intensity changing unit changes the intensity of the pulse light from the light source such that the following Conditional Expression (1) is satisfied:
1.05<IP/IT<2.7 (1)
where IT is the threshold calculated by the threshold calculation unit, and IP is a peak value of intensity at a focus position of the pulse light after the change.

### Claim 9 (depends on 1)

The photoacoustic microscope according to claim 1, wherein a pulse width of the pulse light from the light source satisfies the following Conditional Expression (2):
50 ns<PW<500 ns (2)
where PW is the pulse width of the pulse light from the light source.

### Claim 10 (depends on 1)

The photoacoustic microscope according to claim 1, further comprising a pulse width changing unit which change a pulse width of the pulse light from the light source.

### Claim 11 (depends on 10)

The photoacoustic microscope according to claim 10, wherein the pulse width changing unit increases the pulse width of the pulse light in accordance with the information included in the information unit and representing the relation between the intensity of the pulse light entering the sample and the intensity of the acoustic signal generated from the sample.

### Claim 12 (depends on 10)

The photoacoustic microscope according to claim 10 further comprising:
the pulse width changing unit which change a pulse width of the pulse light from the light source,
wherein the pulse width changing unit increases the pulse width of the pulse light when the threshold is smaller than a predetermined value.

### Claim 13 (depends on 1)

The photoacoustic microscope according to claim 1, further comprising a scanning unit which two-dimensionally or three-dimensionally moves a position thereof relative to the pulse light and the sample.

### Claim 14

A photoacoustic signal detection method, comprising:
emitting pulse light;
focusing the pulse light emitted at the emission step and irradiating a sample with the focused pulse light;
detecting an acoustic signal generated from the sample through irradiation of the pulse light;
forming an image signal of the sample based on the acoustic signal;
providing an information representing a relation between intensity of the pulse light entering the sample and intensity of the acoustic signal generated from the sample; and
changing intensity of the pulse light from a light source based on the information.

### Claim 15 (depends on 14)

The photoacoustic signal detection method according to claim 14, further comprising:
displaying the information at the information step.

### Claim 16 (depends on 14)

The photoacoustic signal detection method according to claim 14, wherein the information step comprises an information generation step of generating the information representing the relation between the intensity of the pulse light entering the sample and the intensity of the acoustic signal generated from the sample.

### Claim 17 (depends on 14)

The photoacoustic signal detection method according to claim 14, wherein the information step comprises an information storage step of storing the information representing the relation between the intensity of the pulse light entering the sample and the intensity of the acoustic signal generated from the sample.

### Claim 18 (depends on 16)

The photoacoustic signal detection method according to claim 16, wherein the information generation step comprises a threshold calculation step of calculating, based on the information, as a threshold, pulse light intensity with which the intensity of the acoustic signal relative to the intensity of the pulse light starts to increase.

### Claim 19 (depends on 17)

The photoacoustic signal detection method according to claim 17, wherein the information storage step comprises storing, as a threshold, pulse light intensity with which the intensity of the acoustic signal relative to the intensity of the pulse light starts to increase.

### Claim 20 (depends on 18)

The photoacoustic signal detection method according to claim 18, further comprising:
changing, based on the threshold calculated at the threshold calculation step, the intensity of the pulse light generated at the emission step to be equal to or more than the threshold.

### Claim 21 (depends on 20)

The photoacoustic signal detection method according to claim 20, wherein the pulse light intensity changing step comprises changing the intensity of the pulse light generated at the emission step such that the following Conditional Expression (1) is satisfied:
1.05<IP/IT<2.7 (1)
where IT is the threshold calculated at the threshold calculation step, and IP is a peak value of intensity at a focus position of the pulse light after the change.

### Claim 22 (depends on 15)

The photoacoustic signal detection method according to claim 15, wherein a pulse width of the pulse light at the emission step satisfies the following Conditional Expression (2):
50 ns<PW<500 ns (2)
where PW is a pulse width of the pulse light at the emission step.

### Claim 23 (depends on 15)

The photoacoustic signal detection method according to claim 15, further comprising:
changing a pulse width of the pulse light at the emission step.

### Claim 24 (depends on 23)

The photoacoustic signal detection method according to claim 23, wherein the pulse width changing step comprises increasing the pulse width of the pulse light in accordance with the information at the information step, the information representing the relation between the intensity of the pulse light entering the sample and the intensity of the acoustic signal generated from the sample.

### Claim 25 (depends on 23)

The photoacoustic signal detection method according to claim 23 further comprising:
changing, based on the threshold calculated at the threshold calculation step,
wherein the pulse width changing step comprises increasing the pulse width of the pulse light when the threshold is smaller than a predetermined value.

### Claim 26 (depends on 15)

The photoacoustic signal detection method according to claim 15, further comprising:
moving relative positions of the pulse light and the sample two-dimensionally or three-dimensionally by scan.