In spectroscopy of gases, in order to obtain a sensitive enough measurement of the absorption, it is often required to have long optical path lengths. Multiple-pass cells, where the gas-filled volume is encased between mirrors, are a way of fulfilling this requirement while at the same time controlling beam divergence on the way and preempting the need for extremely large devices. The Herriott cell is one example of this kind of system, characterized by the use of two spherical mirrors with a single off-axis hole drilled into one of them to allow for the entry and exit of the beam. The curvature of the mirrors redirects the beam and controls its divergence.
In today’s newsletter we want to demonstrate the simulation of one such Herriott cell. We have used the Parameter Coupling to link several system parameters together, in order to ensure the correct configuration of the setup while allowing the user to investigate the effect of varying, for instance, the distance between mirrors.
Modeling of a Herriott-Cell
This use case shows a physical optics simulation of a Herriott cell for gas spectroscopy, including a demonstration with CO2.
This example provides a step-by-step explanation of how to link two parameters of an optical system (e.g. of a grating). As a result, both parameters will automatically show an identical value, also when that value is modified.
