Apparatus and method for detecting scattered material by Terahertz Wave

• US 20060043298A1
• Filed: 09/01/2005
• Published: 03/02/2006
• Est. Priority Date: 09/01/2004
• Status: Active Grant

• Current Assignee: Riken, Shibuya Seiki Co., Ltd. (Shibuya Corporation)
• Original Assignee: Riken, Si Seiko Co., Ltd. (Shibuya Corporation)
• Inventors: Kawase, Kodo, Shibuya, Takayuki, Ogawa, Yuichi, Yamashita, Masahiro
• Granted Patent: US 7,291,838 B2
• Time in Patent Office: Days
• US Class Current: 250/339.60
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: G01V 8/005 operating with millimetre waves, e.g. measuring the black losey radiation

Abstract

There is disclosed an apparatus comprising: a terahertz wave generation device which generates a terahertz wave; a terahertz wave irradiation device which irradiates an object to be inspected with the terahertz wave; and a scattering intensity detection device which cuts a rectilinear wave of the terahertz wave which has passed through the object to be inspected and which detects an intensity of a scattered wave, and a scattered material such as powder or foam contained in an envelope, a capsule, a container or the like is detected in a non-destructive manner without unsealing the envelope or the like.

Claims

1. A scattered material detection apparatus using a terahertz wave, comprising:

a terahertz wave generation device which generates the terahertz wave;

a terahertz wave irradiation device which irradiates an object to be inspected with the terahertz wave; and

a scattering intensity detection device for cutting a rectilinear wave of the terahertz wave which has passed through the object to be inspected and for detecting an intensity of a scattered wave.

2. The scattered material detection apparatus according to claim 1, wherein the terahertz wave irradiation device comprises:

a lens which converts the generated terahertz wave into parallel light; and

an iris diaphragm which limits a sectional shape of the parallel light to be smaller than that of the object to be inspected to irradiate the object with the light, and

the scattering intensity detection device comprises;

a confocal optical system for interrupting the terahertz wave which has rectilinearly passed through the object to be inspected midway and for focusing the terahertz wave scattered by the object to be inspected in a predetermined position; and

a scattering intensity detection unit which detects the intensity of the terahertz wave in the focal position.

3. The scattered material detection apparatus according to claim 2, wherein the confocal optical system comprises:

first and second off-axis parabolic mirrors which face each other; and

a shielding member which is positioned between the two off-axis parabolic mirrors and which cuts the rectilinear wave of the terahertz wave and which transmits the scattered wave,

the first off-axis parabolic mirror has an incidence-side focus and a reflection-side focus along an axial line of the terahertz wave,

the object to be inspected is positioned in the incidence-side focus of the first off-axis parabolic mirror or its vicinity, and

the shielding member is positioned in the reflection-side focus of the first off-axis parabolic mirror or its vicinity.

4. The scattered material detection apparatus according to claim 2, wherein the confocal optical system comprises:

first and second convex lenses which face each other; and

a shielding member which is positioned between two convex lenses and which cuts the rectilinear wave of the terahertz wave and which transmits the scattered wave,

the first convex lens has an incidence-side focus and an outlet-side focus along an axial line of the terahertz wave,

the object to be inspected is positioned in the incidence-side focus of the first convex lens or its vicinity, and

the shielding member is positioned in the outlet-side focus of the first convex lens or its vicinity.

5. A scattered material detection method using a terahertz wave, comprising:

a terahertz wave generating step of generating the terahertz wave;

a terahertz wave irradiating step of irradiating an object to be inspected with the terahertz wave; and

a scattering intensity detecting step of cutting a rectilinear wave of the terahertz wave which has passed through the object to be inspected and detecting an intensity of a scattered wave.

6. The scattered material detection method according to claim 5, wherein in the terahertz wave irradiating step, the terahertz wave generated in the terahertz wave generating step is converted into parallel light, and a sectional shape of the parallel light is limited to be smaller than that of the object to be inspected to irradiate the object with the light, and

in the scattering intensity detecting step, the terahertz wave which has rectilinearly passed through the object to be inspected is interrupted midway, the terahertz wave scattered by the object to be inspected is focused in a predetermined position, and the intensity of the terahertz wave in the focal position is detected.