Terahertz wave spectroscopic measurement device

Patent metadata

Field	Value
Publication number	US-10697891-B2
Application number	US-201916245355-A
Country	US
Kind code	B2
Filing date	Jan 11, 2019
Priority date	Jan 29, 2018
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A terahertz wave spectroscopic measurement device includes a light source that emits a terahertz wave and probe light having a wavelength different from that of the terahertz wave, an internal total reflection prism including an incidence surface of the terahertz wave, a placement surface on which a measurement target is placed, and an emission surface of the terahertz wave, the internal total reflection prism internally totally reflecting the terahertz wave incident from the incidence surface by means of the placement surface and emitting the terahertz wave from the emission surface, and a terahertz wave detection unit that indirectly detects the terahertz wave emitted from the emission surface using the probe light. The internal total reflection prism includes an avoidance portion on which incidence of the probe light on the measurement target on the placement surface is avoided.

First claim

What is claimed is:

1. A terahertz wave spectroscopic measurement device comprising:
a light source that emits terahertz waves and probe light having a wavelength different from that of the terahertz waves;
an internal total reflection prism including an incidence surface of the terahertz waves, a placement surface on which a measurement target is placed, and an emission surface of the terahertz waves, the internal total reflection prism internally totally reflecting the terahertz waves incident from the incidence surface by means of the placement surface and emitting the terahertz waves from the emission surface; and
a terahertz wave detection unit that indirectly detects the terahertz waves emitted from the emission surface using the probe light,
wherein the internal total reflection prism includes an avoidance portion on which incidence of the probe light on the measurement target on the placement surface is avoided.

2. The terahertz wave spectroscopic measurement device according to claim 1 , wherein the avoidance portion includes an optical branching portion that guides the terahertz waves to the placement surface and does not guide the probe light to the placement surface.

3. The terahertz wave spectroscopic measurement device according to claim 2 , wherein the optical branching portion includes an optical element that reflects the terahertz waves incident on the internal total reflection prism from the incidence surface, toward the placement surface, and transmits the probe light incident on the internal total reflection prism from the incidence surface, toward the emission surface.

4. The terahertz wave spectroscopic measurement device according to claim 2 , wherein the optical branching portion includes an optical element that guides the terahertz waves incident on the internal total reflection prism from the incidence surface, to the emission surface via the placement surface, and reflects the probe light by means of the incidence surface to guide the probe light to the emission surface without being incident on the internal total reflection prism.

5. The terahertz wave spectroscopic measurement device according to claim 2 ,
wherein the optical branching portion includes an air gap portion provided in the internal total reflection prism, and
a spacing of the air gap portion is smaller than a penetration depth of an evanescent component of the terahertz waves at an interface with the internal total reflection prism and is larger than a penetration depth of an evanescent component of the probe light at the interface.

6. The terahertz wave spectroscopic measurement device according to claim 1 , wherein the avoidance portion includes an optical branching portion that branches, on the placement surface, the terahertz waves and the probe light incident on the internal total reflection prism.

7. The terahertz wave spectroscopic measurement device according to claim 6 , wherein the optical branching portion includes an optical element that is disposed on the placement surface to transmit the terahertz waves and reflect the probe light.

8. The terahertz wave spectroscopic measurement device according to claim 6 , wherein the optical branching portion includes
a condensing lens that condenses the terahertz waves and the probe light on the placement surface, and
a metal film that is disposed on the placement surface and has an area smaller than a condensing diameter of the terahertz waves on the placement surface and larger than a condensing diameter of the probe light on the placement surface.

9. The terahertz wave spectroscopic measurement device according to claim 6 , wherein the optical branching portion includes a spacer that is disposed on the placement surface and forms a spacing smaller than a penetration depth of an evanescent component of the terahertz waves on the placement surface and larger than a penetration depth of an evanescent component of the probe light on the placement surface, between the placement surface and the measurement target.

10. The terahertz wave spectroscopic measurement device according to claim 1 ,
wherein optical axes of the terahertz waves and the probe light incident on the incidence surface are coaxial, and
optical axes of the terahertz waves and the probe light emitted from the emission surface are coaxial.

11. The terahertz wave spectroscopic measurement device according to claim 1 , further comprising an attenuator that attenuates an intensity of the probe light.

Assignees

• Hamamatsu Photonics Kk

Inventors

• Nakanishi Atsushi
• Fujita Kazuue
• Horita Kazuki

Classifications

• G01J3/0208

  using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction · CPC title

• G02B5/04

  Prisms · CPC title

• G01J3/42 Primary

  Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry (beam switching arrangements G01J3/08) · CPC title

• G01N21/3581

  using far infrared light; using Terahertz radiation · CPC title

• G01J3/0213

  using attenuators · CPC title