Apparatus and method for obtaining sample information by detecting electromagnetic wave

• US 20070252992A1
• Filed: 04/20/2007
• Published: 11/01/2007
• Est. Priority Date: 04/28/2006
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Itsuji, Takeaki
• Granted Patent: US 7,619,736 B2
• Time in Patent Office: Days
• US Class Current: 356/369
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation

Abstract

A sample information obtaining apparatus includes an electromagnetic wave generator; a sample holding unit which holds a sample to be tested and serves as a polarizer having a polarization axis which defines how an incident electromagnetic wave is to be divided according to a polarization state of the incident electromagnetic wave; an electromagnetic wave detecting unit which separately detects a transmitted electromagnetic wave transmitted through the sample holding unit and a reflected electromagnetic wave reflected off the sample holding unit, the transmitted and reflected electromagnetic waves being obtained by dividing the incident electromagnetic wave incident on the sample holding unit according to a relative positional relationship between the polarization state of the incident electromagnetic wave and the polarization axis of the sample holding unit; and a processor which processes signals of the electromagnetic waves detected by the electromagnetic wave detecting unit and obtains information about the sample.

Claims

1. A sample information obtaining apparatus comprising:

an electromagnetic wave generator configured to generate electromagnetic waves;

a sample holding unit configured to provide a function of a polarizer having a polarization axis which defines how an incident electromagnetic wave is to be divided according to a polarization state of the incident electromagnetic wave, the sample holding unit being configured to hold a sample to be tested;

an electromagnetic wave detecting unit configured to separately detect a transmitted electromagnetic wave transmitted through the sample holding unit and a reflected electromagnetic wave reflected off the sample holding unit, the transmitted electromagnetic wave and the reflected electromagnetic wave being obtained by dividing the incident electromagnetic wave propagating from the electromagnetic wave generator and made incident on the sample holding unit, according to a relative positional relationship between the polarization state of the incident electromagnetic wave and the polarization axis of the sample holding unit; and

a processor configured to process signals of the transmitted and reflected electromagnetic waves detected by the electromagnetic wave detecting unit and obtain information about the sample.

2. The sample information obtaining apparatus according to claim 1, wherein the sample information obtaining apparatus is configured such that the polarization state of the incident electromagnetic wave with respect to the polarization axis can be temporally varied.

3. The sample information obtaining apparatus according to claim 2, wherein at least one of the electromagnetic wave generator and the sample holding unit has a polarization state controller which temporally varies the polarization state of the incident electromagnetic wave with respect to the polarization axis.

4. The sample information obtaining apparatus according to claim 3, wherein the polarization state controller comprises a rotation mechanism for rotating the at least one of the electromagnetic wave generator and the sample holding unit.

5. The sample information obtaining apparatus according to claim 1, wherein the sample information obtaining apparatus is configured such that the polarization state of the incident electromagnetic wave with respect to the polarization axis can be fixed such that the incident electromagnetic wave has a component inclined with respect to the polarization axis.

6. The sample information obtaining apparatus according to claim 1, further comprising:

a scanning unit configured to vary a relative positional relationship between the sample held by the sample holding unit and the incident electromagnetic wave, in a direction in a plane of the sample facing an incident direction of the incident electromagnetic wave incident on the sample holding unit,

wherein the electromagnetic wave detecting unit detects the transmitted electromagnetic wave and the reflected electromagnetic wave at each electromagnetic wave incident point at which an electromagnetic wave is incident on the sample; and

a processor separately determines signals of the transmitted electromagnetic wave and reflected electromagnetic wave with respect to each electromagnetic wave incident point and obtains the resulting distributions of two-dimensional spatial arrangements of the determined signals as a transmitted image and a reflected image of the sample.

7. The sample information obtaining apparatus according to claim 1, wherein the electromagnetic wave detecting unit includes a plurality of detectors which detect the transmitted electromagnetic wave and the reflected electromagnetic wave separately from the sample holding unit.

8. The sample information obtaining apparatus according to claim 1, further comprising:

a selecting unit configured to sequentially select the transmitted electromagnetic wave and the reflected electromagnetic wave,

wherein one detector in the electromagnetic wave detecting unit detects the transmitted electromagnetic wave and the reflected electromagnetic wave.

9. The sample information obtaining apparatus according to claim 1, wherein the sample holding unit comprises a wire grid.

10. The sample information obtaining apparatus according to claim 9, wherein spaces between adjacent wires of the wire grid are filled with a filling material.

11. The sample information obtaining apparatus according to claim 9, wherein the sample is a solution that fills spaces between adjacent wires of the wire grid.

12. A sample information obtaining method comprising:

holding a sample to be tested on a sample holding unit configured to provide a function of a polarizer having a polarization axis which defines how an incident electromagnetic wave is to be divided according to a polarization state of the incident electromagnetic wave;

making an electromagnetic wave incident on the sample holding unit which holds the sample;

dividing the incident electromagnetic wave into a transmitted electromagnetic wave transmitted through the sample holding unit and a reflected electromagnetic wave reflected off the sample holding unit, according to a relative positional relationship between the polarization state of the incident electromagnetic wave and the polarization axis of the sample holding unit;

detecting the transmitted electromagnetic wave and the reflected electromagnetic wave separately; and

obtaining information about the sample on the basis of signals of the detected electromagnetic waves.

13. The sample information obtaining method according to claim 12, further comprising:

varying a relative positional relationship between the sample held by the sample holding unit and the incident electromagnetic wave, in a direction in a plane of the sample facing an incident direction of the incident electromagnetic wave incident on the sample holding unit;

detecting the transmitted electromagnetic wave and the reflected electromagnetic wave at each electromagnetic wave incident point at which an electromagnetic wave is incident on the sample;

separately determining signals of the transmitted electromagnetic wave and reflected electromagnetic wave with respect to each electromagnetic wave incident point; and

obtaining the resulting distributions of two-dimensional spatial arrangements of the determined signals as a transmitted image and a reflected image of the sample.

14. The sample information obtaining method according to claim 12, wherein the electromagnetic wave is a terahertz wave in the frequency range of 30 gigahertz to 30 terahertz.

15. The sample information obtaining method according to claim 12, wherein the polarization state of the incident electromagnetic wave with respect to the polarization axis is temporally varied.

16. The sample information obtaining method according to claim 12, wherein the polarization state of the incident electromagnetic wave with respect to the polarization axis is fixed such that the incident electromagnetic wave has a component inclined with respect to the polarization axis.