このアプリケーションの一部のコンテンツは現時点では利用できません。
このような状況が続く場合は、にお問い合わせくださいフィードバック & お問い合わせ
1. (WO2017033037) TERAHERTZ WAVEFRONT MEASUREMENT SYSTEM AND METHOD
注意: このテキストは、OCR 処理によってテキスト化されたものです。法的な用途には PDF 版をご利用ください。

CLAIMS

1 . Terahertz wavefront measurement system comprising :

- a spatial mask (4, 24) selected among a Terahertz lens array (24) or an array of apertures (4, 14), the spatial mask (4, 24) being configured and placed for receiving an incident pulsed beam (10) in a Terahertz frequency range and for generating an array of multispots (60, 61 , 70, 71 ) in the Terahertz frequency range,

- an infrared camera (9) comprising an array of pixels;

- a nonlinear electro-optical crystal (5) placed between the spatial mask (4, 24) and the infrared camera (9), the nonlinear electro-optical crystal (5) having a first face and a second face, the first face being placed adjacent to the spatial mask (4, 24) for receiving the array of multispots in the Terahertz frequency range and the second face being placed for receiving an ultrashort pulsed infrared probe beam (20), the nonlinear electro-optical crystal (5) being configured for providing nonlinear electro-optical interaction between the array of multispots in the Terahertz frequency range and the ultrashort pulsed infrared collimated probe beam (20) and for generating a reflected beam (30) in the infrared frequency range having a wavefront spatial distribution depending on the array of multispots in the Terahertz frequency range;

- the camera (9) being configured for detecting an image of the reflected beam (30) in the infrared frequency range; and

- a processing system for analyzing the image of reflected beam (30) in the infrared frequency range and for reconstructing a wavefront spatial distribution of the incident beam (10) in the Terahertz frequency range for a determined frequency range.

2. Terahertz wavefront measurement system according to claim 1 wherein the nonlinear electro-optical crystal (5) comprises a plate of zinc telluride, gallium phosphide, LiNbO3 or DAST.

3. Terahertz wavefront measurement system according to claim 1 or 2 wherein the distance (D) between the spatial mask (4, 24) and the nonlinear electro-optical crystal (5) is from 1 to 10 mm.

4. Terahertz wavefront measurement system according to any one of claims 1 to 3 wherein the spatial mask (4, 24) comprises a two-dimension periodic array of apertures (4, 14) or, respectively, a two-dimension periodic array of lenses (34), the period(s) of the two-dimension periodic array being comprised between 1 and 5 millimeters, and the dimensions of the apertures (14), respectively of the lenses (34), being comprised between 0.5 and 2.5 millimeters.

5. Terahertz wavefront measurement system according to any one of claims 1 to 4, further comprising a polarizer (7) placed on a beam path of the ultrashort pulsed infrared probe beam (20), an analyzer (17) placed between the nonlinear electro-optic crystal (5) and the infrared camera (9) and a beam splitter (6) for separating the ultrashort pulsed infrared probe beam (20) from the reflected beam (30) in the infrared frequency range.

6. Terahertz wavefront measurement system according to any one of claims 1 to 5, further comprising an optical delay line (22) placed on a beam path of the ultrashort pulsed infrared probe beam (20), the infrared camera (9) being configured for detecting a plurality of images as a function of a time delay of the delay line (22) and the processing system being configured for analyzing the plurality of images as a function of a time delay.

7. Terahertz wavefront measurement system according to any one of claims 1 to 6, further comprising a modulator (3) for modulating the incident beam

(10) in the Terahertz frequency range, and a synchronization line (19) for synchronizing the infrared camera (9) with the modulator (3).

8. Terahertz wavefront measurement system according to any one of claims 1 to 7, further comprising an optional Terahertz beam expander (1 1 ) placed on a beam path of the incident beam (10) in the Terahertz frequency range, and/or an infrared beam expander (12) placed on a beam path of the ultrashort pulsed infrared probe beam (20).

9. Terahertz wavefront measurement system according to any one of claims 1 to 8, further comprising a Terahertz source comprising an air plasma, or an interdigited photoconductive antenna or another nonlinear optical crystal (15) configured for receiving an ultrashort laser pulsed beam (40) and for generating by optical rectification the incident beam (10) in the Terahertz frequency range.

10. Terahertz wavefront measurement method comprising the steps of:

- directing an incident beam (10) in a Terahertz frequency range on a

spatial mask (4, 24) selected among a Terahertz lens array (24) or an array of apertures (4, 14), the spatial mask (4, 24) being configured so as to generate an array of multispots in the Terahertz frequency range; and

- directing the array of multispots in the Terahertz frequency range on a first face of a nonlinear electro-optical crystal (5) adjacent to the spatial mask (4,

24) and directing an ultrashort pulsed infrared probe beam (20) on a second face of the nonlinear electro-optical crystal (5), the nonlinear electro-optical crystal (5) being configured for providing nonlinear electro-optical interaction between the array of multispots in the Terahertz frequency range and the ultrashort pulsed infrared probe beam (20) and for generating a reflected beam (30) in the infrared frequency range having a wavefront spatial distribution depending on the array of multispots in the Terahertz frequency range;

- detecting an image of the reflected beam (30) in the infrared frequency range on an array of pixels of an infrared camera; and

- analyzing the image of reflected beam (30) in the infrared frequency range and reconstructing a wavefront spatial distribution of the incident beam (10) in the Terahertz frequency range for a determined frequency range.