INSPECTION APPARATUS USING THzBAND

• US 20170234807A1
• Filed: 10/09/2015
• Published: 08/17/2017
• Est. Priority Date: 10/14/2014
• Status: Active Grant

• Current Assignee: Laurel Precision Machines Co., Ltd.
• Original Assignee: Laurel Precision Machines Co., Ltd.
• Inventors: Oyama, Yutaka, Goi, Kouichi
• Granted Patent: US 11,385,186 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 2021/8917 Paper, also ondulated
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: G01N 21/8914 characterised by the material examined
• CPC Class Codes: G01N 21/892 characterised by the flaw, defect or object feature examined
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G01N 22/02 Investigating the presence of flaws
• CPC Class Codes: G01N 33/346 paper sheets
• CPC Class Codes: G07D 7/12 Visible light, infrared or ultraviolet radiation
• CPC Class Codes: G07D 7/121 Apparatus characterised by sensor details
• CPC Class Codes: G07D 7/189 Detecting attached objects, e.g. tapes or clips G07D7/187 takes precedence

Abstract

An inspection device of the present invention includes: THz wave irradiation unit for irradiating a specimen with THz waves; a THz wave sensing unit for detecting transmitted waves or reflected waves of the THz waves emitted to the specimen; and an information processing unit for acquiring intensity distribution of the transmitted waves of the reflected waves of the specimen from the intensity data of the transmitted waves or the reflected waves of the specimen irradiated with the THz waves, wherein the information processing unit acquires 2-dimensional intensity distribution of the transmitted waves or reflected waves, and detects whether a foreign matter is adhering to the specimen by comparing the intensity distribution obtained when the specimen without attachment of the foreign matter is detected and the intensity distribution obtained when the specimen is detected at the time of inspection. The specimen is a sheet of paper, for example.

Claims

1. An inspection device, comprising;

a THz wave irradiation unit for irradiating a specimen with THz waves;

a THz wave sensing unit for detecting transmitted waves or reflected waves of the THz waves emitted to the specimen; and

an information processing unit for acquiring an intensity distribution of the transmitted waves or the reflected waves of the specimen from intensity data of the transmitted waves or the reflected waves of the specimen irradiated with the THz waves,

wherein the information processing unit acquires 2-dimensional intensity distribution of the transmitted waves or the reflected waves, and

detects whether a foreign matter is adhering to the specimen at the time of inspection is detected by comparing the intensity distribution obtained when the specimen without attachment of the foreign matter is detected and the intensity distribution obtained when the specimen is detected at the time of inspection.

2. The inspection device as set faith in claim 1, wherein the information processing unit detects the foreign matter adhering to the specimen from change in intensity by lens effect based on a difference between refraction index of the foreign matter and refraction index of the specimen without attachment of the foreign matter.

5. The inspection device as set forth in claim 1, wherein the THz wave irradiation unit includes:

a THz wave oscillator;

a light-collecting optical component for scanning THz waves emitted from the THz wave oscillator; and

a scanning device.

6. The inspection device as set forth in claim 5, wherein the scanning device is any one of galvanometer mirror, polygon mirror, and digital minor devices.

7. The inspection device as set forth in claim 1, wherein the THz wave irradiation unit comprises:

a plurality of THz wave oscillators; and

optical components.

9. The inspection device as set forth in claim 5, wherein the light-collecting optical component is selected from a Fresnel lens, convex lens, concave lens and minor.

10. The inspection device as set forth in claim 1, wherein the THz wave sensing unit comprises:

a plurality of THz wave detectors; and

optical components.

11. The inspection device as set forth in claim 2, wherein the information processing unit has a function of 2-dimensionnaly displaying the change in intensity by the lens effect in different gradations.

12. The inspection device as set claim 1, wherein the foreign matter is a resin film.

14. The inspection device as set forth in claim 1, wherein the THz wave irradiation unit has a multiple-frequency THz, wave oscillator.

15. The inspection device as set forth in claim 1, wherein a polarization direction of THz waves emitted from the THz wave irradiation unit and a polarization direction of THz waves falling on the THz wave detector are controlled.

3. An inspection device, comprising:

a paper transfer unit for transferring a sheet of paper;

a THz wave irradiation unit for irradiating THz waves in a direction orthogonal to a transfer direction of the paper transfer unit;

a THz wave sensing unit for detecting the transmitted waves or the reflected waves of the THz waves emitted to the sheet of paper; and

an information processing unit for acquiring intensity distribution of the transmitted waves or the reflected waves of the sheet of paper from intensity data of the transmitted waves or the reflected waves of the sheet of paper irradiated with THz waves in a direction orthogonal to the direction of transfer,

wherein the information processing unit acquires 2-dimensional intensity distribution of the transmitted waves or the reflected waves, and

detects whether a foreign matter is adhering to the sheet of paper at the time of inspection or not is detected by comparing the intensity distribution obtained when the sheet of paper without attachment of the foreign matter is detected and the intensity distribution obtained when the sheet of paper is detected at the time of inspection.

4. The inspection device as set forth in claim 3, wherein the information processing unit detects the foreign matter adhering to the sheet of paper from the change in intensity by lens effect based on the difference between refraction index of the foreign matter and refraction index of the sheet of paper without attachment of the foreign matter.

8. The inspection device as set forth in claim 3, wherein the THz wave sensing unit comprises:

a THz, wave detector; and

a light-collecting optical component for collecting the transmitted waves or the reflected waves of the TH waves emitted to the sheet of paper.

13. The inspection device as set forth in claim 3, wherein a resin or glass that transmits THz waves is disposed on top and bottom face of the sheet of paper.