Photothermal conversion measurement apparatus, photothermal conversion measurement method, and sample cell

• US 20060181708A1
• Filed: 02/10/2006
• Published: 08/17/2006
• Est. Priority Date: 02/14/2005
• Status: Active Grant

• Current Assignee: Klaus Schmidt
• Original Assignee: Klaus Schmidt
• Inventors: Takahashi, Eiji, Sakoda, Naokazu, Takamatsu, Hiroyuki, Kannaka, Masato, Morimoto, Tsutomu
• Granted Patent: US 7,522,287 B2
• Time in Patent Office: Days
• US Class Current: 356/432
• CPC Class Codes: G01N 2021/1712 Thermal lens, mirage effect
• CPC Class Codes: G01N 2021/178 Methods for obtaining spatial resolution of the property being measured
• CPC Class Codes: G01N 21/031 Multipass arrangements
• CPC Class Codes: G01N 21/171 with calorimetric detection, e.g. with thermal lens detection
• CPC Class Codes: G01N 21/45 using interferometric methods; using Schlieren methods
• CPC Class Codes: G01N 2201/105 Purely optical scan

Abstract

A liquid sample is irradiated with excitation light and measurement light, and a measurement position at which a traveling path of the measurement light passes through an excitation section of the excitation light in the sample is changed while the sample is being irradiated with the excitation light and the measurement light. Then, the phase change of the measurement light is measured for each measurement by optical interferometry on the basis of the measurement light after the measurement light passes through the sample. The measurement position is changed by, for example, scanning the excitation light, moving the sample, moving a lens that collects the excitation light in the sample so as to change the light-collecting position (focal position) in the sample, etc.

Claims

1. A photothermal conversion measurement apparatus for measuring a property change of a sample caused by a photothermal effect of the sample when the sample is irradiated with excitation light, the photothermal conversion measurement apparatus comprising:

measurement-light-emitting means for irradiating the sample with predetermined measurement light;

measurement-position-changing means for changing a measurement position at which a traveling path of the measurement light passes through an excitation section of the excitation light in the sample;

light-measuring means for measuring the property change of the sample for each measurement position set by the measurement-position-changing mechanism on the basis of the measurement light after the measurement light passes through the sample.

2. The photothermal conversion measurement apparatus according to claim 1, wherein a phase change of the measurement light that passes through the sample is measured as the property change of the sample.

3. The photothermal conversion measurement apparatus according to claim 1, wherein the measurement-position-changing means includes optical-path-changing means that changes the measurement position by changing an optical path of the excitation light.

4. The photothermal conversion measurement apparatus according to claim 3, wherein the optical-path-changing means includes first optical-path-changing means that changes an incident position and/or an incident direction of the excitation light that is incident on the sample in a direction that intersects an incident direction of the measurement light on the sample.

5. The photothermal conversion measurement apparatus according to claim 3, wherein the optical-path-changing means includes:

a lens that allows the excitation light to pass therethrough in substantially the same direction as an incident direction of the measurement light on the sample while collecting the excitation light; and

second optical-path-changing means that moves the lens in substantially the same direction as the incident direction of the measurement light to change a focus position of the excitation light in the sample.

6. The photothermal conversion measurement apparatus according to claim 1, wherein the measurement-position-changing means includes sample-moving means that changes the measurement position by moving the sample.

7. The photothermal conversion measurement apparatus according to claim 1, further comprising:

two light-reflecting means arranged so as to face each other across the sample and repeatedly reflecting the measurement light incident on the sample between the two light-reflecting means along one axis while allowing the measurement light to pass through the sample, at least one of the two light-reflecting means allowing a part of the measurement light to pass therethrough; and

light-intensity-detecting means that receives the measurement light that passes through said at least one of the light-reflecting means in a direction away from the sample and detects the intensity of the received measurement light.

8. The photothermal conversion measurement apparatus according to claim 7, further comprising a distance-adjusting means for adjusting a distance between the two light-reflecting means such that variation in a detection signal obtained by the light-intensity-detecting means is reduced.

9. The photothermal conversion measurement apparatus according to claim 7, further comprising:

intensity-modulating means for periodically modulating the intensity of the excitation light incident on the sample; and

periodic-component-extracting means that extracts a periodic component with the same period as the intensity modulation period of the excitation light from a detection signal obtained by the light-intensity-detecting means.

10. The photothermal conversion measurement apparatus according to claim 7, further comprising variable spectroscopic means that outputs light obtained by dividing white light into spectral components as the excitation light and that is capable of varying the wavelength range of the excitation light.

11. The photothermal conversion measurement apparatus according to claim 1, further comprising excitation-light-deflecting means that deflects the excitation light after the excitation light passes through the sample so that the excitation light is redirected to the sample.

12. The photothermal conversion measurement apparatus according to claim 11, wherein the excitation-light-deflecting means redirects the excitation light such that the excitation light is incident on the sample at the same portion as the portion at which the excitation light is incident on the sample the first time.

13. The photothermal conversion measurement apparatus according to claim 1, further comprising light-collecting means that collects the excitation light at a predetermined portion in the sample.

14. The photothermal conversion measurement apparatus according to claim 13, wherein the light-collecting means includes a lens and/or a concave mirror.

15. The photothermal conversion measurement apparatus according to claim 14, wherein the photothermal conversion measurement apparatus includes a single concave mirror that serves as both the excitation-light-deflecting means and the light-collecting means that collects the excitation light that passes through the sample.

16. The photothermal conversion measurement apparatus according to claim 1, further comprising filter means for reducing or eliminating a component with a main light-absorption wavelength range of a sample cell in which the sample is contained from the excitation light incident on the sample.

17. The photothermal conversion measurement apparatus according to claim 16, wherein the filter means includes a wavelength selecting filter.

18. The photothermal conversion measurement apparatus according to claim 16, wherein the filter means includes a member similar to the sample cell, the member being made of a material having the main light-absorption wavelength range of the sample cell.

19. The photothermal conversion measurement apparatus according to claim 16, wherein the filter means includes a sample cell member that is made of the same material as the material of the sample cell.

20. The photothermal conversion measurement apparatus according to claim 16, wherein the filter means includes an enclosing-agent container containing an enclosing agent identical to that enclosed in the sample cell together with the sample.

21. The photothermal conversion measurement apparatus according to claim 19, wherein the sample cell member functions as the enclosing-agent container.

22. A photothermal conversion measurement apparatus for measuring a property change of a sample caused by a photothermal effect of the sample when the sample is irradiated with excitation light, the property change being measured on the basis of a phase change of predetermined measurement light that passes through the sample, the photothermal conversion measurement apparatus comprising:

two light-reflecting means arranged so as to face each other across the sample and repeatedly reflecting the measurement light incident on the sample between the two light-reflecting means along one axis while allowing the measurement light to pass through the sample, at least one of the two light-reflecting means allowing a part of the measurement light to pass therethrough; and

light-intensity-detecting means that receives the measurement light that passes through said at least one of the light-reflecting means in a direction away from the sample and detects the intensity of the received measurement light.

23. A photothermal conversion measurement method for measuring a property change of a sample caused by a photothermal effect of the sample when the sample is irradiated with excitation light, the photothermal conversion measurement method comprising the steps of:

irradiating the sample with predetermined measurement light;

changing a measurement position at which a traveling path of the measurement light passes through an excitation section of the excitation light in the sample;

measuring the property change of the sample for each measurement position on the basis of the measurement light after the measurement light passes through the sample.

24. The photothermal conversion measurement method according to claim 23, wherein a phase change of the measurement light that passes through the sample is measured as the property change of the sample.

25. The photothermal conversion measurement method according to claim 23, further comprising:

a measurement-light reflecting step of repeatedly reflecting the measurement light incident on the sample between two light-reflecting means along one axis while allowing the measurement light to pass through the sample, the two light-reflecting means being arranged so as to face each other across the sample and at least one of the two light-reflecting means allowing a part of the measurement light to pass therethrough; and

a light-intensity-detecting step of receiving the measurement light that passes through said at least one of the light-reflecting means in a direction away from the sample and detecting the intensity of the received measurement light each time the state in which the sample is irradiated with the excitation light is changed,

wherein the property change of the sample caused by the photothermal effect of the sample is measured on the basis of the detection result obtained in the light-intensity-detecting step.

26. The photothermal conversion measurement method according to claim 25, further comprising a wavelength-range-changing step of changing the wavelength range of the excitation light using variable spectroscopic means that outputs light obtained by dividing white light into spectral components as the excitation light and that is capable of varying the wavelength range of the excitation light,

wherein the light-intensity-detecting step is performed each time the wavelength range of the excitation light is changed in the wavelength-range-changing step.

27. The photothermal conversion measurement method according to claim 23, wherein the excitation light is deflected after the excitation light passes through the sample so that the excitation light is redirected to the sample.

28. The photothermal conversion measurement method according to claim 23, wherein a component with a main light-absorption wavelength range of a sample cell in which the sample is contained or a main light-absorption wavelength range of an enclosing agent enclosed in the sample cell together with the sample is reduced or eliminated from the excitation light incident on the sample with a filter.

29. A sample cell that contains a sample in a process of measuring a property change of the sample, the property change being caused by a photothermal effect of the sample when the sample is irradiated with excitation light, the sample cell comprising:

a container section that contains the sample; and

a reflective surface provided on a side of the container section opposite to an incident side at which the excitation light is incident on the container section, the reflective surface reflecting the excitation light after the excitation light passes through the container section so that the excitation light is redirected to the container section.

30. The sample cell according to claim 29, wherein the reflective surface has a concave mirror that collects the excitation light at a predetermined portion of the container section.

31. The sample cell according to claim 30, further comprising a lens on the incident side of the container section at which the excitation light is incident on the container section, the lens collecting the excitation light at the predetermine portion of the container section.