Measuring device for absorption-spectroscopic gas measurement, use of spinel, polycrystalline aluminum oxide or aluminum oxynitride and method for absorption-spectroscopic gas measurement

1 . A measuring device for absorption-spectroscopic gas measurement, comprising:

a radiation device configured to generate a laser beam;

a reflective element configured to reflect the generated laser beam;

at least one detection element configured to detect the reflected laser beam;

a first optical axis along which the generated laser beam is guided to the reflective element; and

a second optical axis along which the reflected laser beam is guided to the at least one detection element,

wherein the reflective element is selected from the group consisting of spinel, polycrystalline aluminum oxide, and aluminum oxynitride, and

wherein the reflective element has a coating selected from the group consisting of Al 2 O 3 /SiO 2 , TiO 2 /Al 2 O 3 , TiO 2 /SiO 2 , Ta 2 O 5 , and MgF 2 .

2 . The measuring device according to claim 1 , wherein the reflective element is a retroreflector.

3 . The measuring device according to claim 1 , wherein the reflective element has an incident surface configured to introduce the generated laser beam into the reflective element, and

wherein the incident surface is designed as a flat surface which is aligned at an angle not equal to 90° to the first optical axis.

4 . The measuring device according to claim 1 , wherein the radiation device is a laser diode.

5 . The measuring device according to claim 4 , wherein the laser diode is tunable.

6 . The measuring device according to claim 5 , wherein the laser diode is tunable over 2.0 μm to 5.0 μm.

7 . The measuring device according to claim 1 , wherein the at least one detection element comprises at least one photodetector.

8 . The measuring device according to claim 1 , wherein the generated laser beam is guided along a section of the first optical axis through a gas mixture.

9 . The measuring device according to claim 8 , wherein the generated laser beam is further guided through the gas mixture along a section of the second optical axis.

10 . The measuring device according to claim 8 , further comprising:

a probe in which the section of the first optical axis extends.

11 . The measuring device according to claim 9 , further comprising:

a probe in which the section of the first optical axis and the section of the second optical axis extend.

12 . The measuring device according to claim 1 , further comprising:

a pure gas delivering device configured to flush the reflective element with a purge gas.

13 . A method of reflecting a laser beam in a measuring device for absorption-spectroscopic gas measurement, the method comprising:

providing a reflective element to reflect the laser beam, the reflective element being selected from the group consisting of spinel, polycrystalline aluminum oxide, and aluminum oxynitride,

wherein the reflective element has a coating selected from the group consisting of Al 2 O 3 /SiO 2 , TiO 2 /Al 2 O 3 , TiO 2 /SiO 2 , Ta 2 O 5 , and MgF 2 .

14 . A method for absorption-spectroscopic gas measurement, comprising:

A. providing a measuring device for the absorption-spectroscopic gas measurement, the measuring device including a radiation device, a reflective element configured to reflect a laser beam generated by the radiation device, at least one detection element configured to detect the reflected laser beam, a first optical axis along which the generated laser beam is guided to the reflective element, and a second optical axis along which the reflected laser beam is guided to the at least one detection element, the reflective element being selected from the group consisting of spinel, polycrystalline aluminum oxide, and aluminum oxynitride;

B. generating, via the radiation device, the laser beam;

C. detecting, via the at least one detection element, the generated laser beam; and

D. conducting, based on the detecting of the generated laser beam, a gas measurement, wherein the reflective element has a coating selected from the group consisting of Al 2 O 3 /SiO 2 , TiO 2 /Al 2 O 3 , TiO 2 /SiO 2 , Ta 2 O 5 , and MgF 2 .