Contents
Source: MDPI
Understanding Multipass Gas Cells in Laser Spectroscopy
Introduction
In laser spectroscopy, measuring the absorption coefficient of light in a gas is crucial for various applications. This is often achieved using multipass gas cells to enhance sensitivity and path length of the light within the gas.
Importance of Multipass Gas Cells
Multipass gas cells enable long path lengths of light in gases, allowing for high sensitivity in spectroscopic measurements. By utilizing multiple reflections within the cell, a longer path length can be achieved without increasing the size of the gas cell significantly.
Designs of Multipass Gas Cells
Various designs of multipass gas cells exist, each with unique features and advantages. Some common designs include Pfund cells, White cells, Herriott cells, and Circular multipass cells. These designs utilize different mirror configurations to achieve multiple reflections and long path lengths for the laser beam within the gas cell.
Pfund Cells
Pfund cells consist of two concave mirrors with holes at the center. The beam is reflected back and forth between the mirrors, providing multiple passes through the gas cell and enhancing the path length of the light.
White Cells
White cells utilize three mirrors, allowing for independent adjustment of orientation to achieve different numbers of passes. This design offers flexibility in controlling the path length of the laser beam within the gas cell.
Herriott Cells
Herriott cells use two spherically curved mirrors to achieve a large number of passes. By carefully positioning the mirrors, multiple reflections can be obtained, enhancing the sensitivity of spectroscopic measurements.
Circular Multipass Cells
Circular multipass cells have reflection points around a circle, enabling a star pattern for the beam path. These cells can utilize separate spherical mirrors or a single circular mirror to achieve multiple passes with a compact design.
Applications of Multipass Gas Cells
Multipass gas cells are not limited to laser spectroscopy but also find applications in optical delay lines in mode-locked lasers and other optical systems requiring long path lengths. These cells offer a versatile solution for enhancing the interaction of light with gases.
Conclusion
Multipass gas cells play a crucial role in laser spectroscopy by enabling long path lengths and high sensitivity in measuring absorption coefficients of gases. Understanding the different designs and applications of multipass gas cells can help researchers and scientists optimize their spectroscopic measurements for various experiments and studies.
Source: MDPI
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