Apparatuses and methods for using the photoacoustic effect

An apparatus, comprising:

• a first optical emitter configured to emit first optical radiation at a first time;
• a second optical emitter configured to emit second optical radiation at a second time;
• at least two hermetically sealed measurement cells arranged in series between the first and the second optical emitters and each filled with a gas configured to absorb the first optical radiation and the second optical radiation at one or more predetermined wavelengths in each case, each of the at least two hermetically sealed measurement cells having a respective microphone arranged therein that is configured to generate a respective microphone signal of a plurality of microphone signals on the basis of a photoacoustic excitation of the gas in the respective measurement cell by the first optical radiation or the second optical radiation;
• at least one area, filled with a gas to be examined, that is arranged between the at least two hermetically sealed measurement cells;
• and
• an evaluation circuit configured to determine an emission intensity of the first optical emitter at the one or more predetermined wavelengths based on a change in a first microphone signal of the plurality of microphone signals after the first time and to determine an emission intensity of the second optical emitter at the one or more predetermined wavelengths based on a change in a second microphone signal of the plurality of microphone signals after the second time.

A method, comprising:

• emitting optical radiation by means of an optical emitter;
• absorbing the optical radiation at one or more predetermined wavelengths by a first gas in a first hermetically sealed measurement cell;
• generating a first microphone signal on a basis of a photoacoustic excitation of the first gas by the optical radiation by a first microphone arranged in the first hermetically sealed measurement cell;
• and
• generating a first measurement signal, indicating an emission intensity of the optical emitter at the one or more predetermined wavelengths, based on the first microphone signal.

A method, comprising:

• emitting first optical radiation at a first time by a first optical emitter;
• emitting second optical radiation at a second time by a second optical emitter;
• absorbing the first optical radiation and the second optical radiation at one or more predetermined wavelengths by a gas in at least two hermetically sealed measurement cells, the at least two hermetically sealed measurement cells being arranged in series between the first and the second optical emitters, and at least one area filled with a gas to be examined being arranged between the at least two hermetically sealed measurement cells;
• generating, for each of the at least two hermetically sealed measurement cells, a respective microphone signal on a basis of a photoacoustic excitation of the gas in a respective measurement cell of the at least two hermetically sealed measurement cells by the first optical radiation or the second optical radiation by a microphone arranged in the respective measurement cell;
• determining an emission intensity of the first optical emitter at the one or more predetermined wavelengths based on a change in a first microphone signal after the first time, the first microphone signal being the respective microphone signal derived from a first one of the at least two hermetically sealed measurement cells;
• and
• determining an emission intensity of the second optical emitter at the one or more predetermined wavelengths based on a change in a second microphone signal after the second time, the second microphone signal being the respective microphone signal derived from a second one of the at least two hermetically sealed measurement cells.