Why Fabry-Perot interferometer is better then Michelson interferometer?

Comparison Between Fabry-Perot and Michelson Interferometers

Fabry-Perot and Michelson interferometers are both fundamental tools in optical engineering and physics, used to measure the wavelength of light, the refractive index of materials, and in various types of spectroscopy. However, they have distinct advantages and applications based on their design and operational principles.

Advantages of Fabry-Perot Interferometer

• Higher Finesse: Fabry-Perot interferometers typically offer higher finesse compared to Michelson interferometers. This results in sharper and more well-defined interference fringes, which are crucial for high-resolution spectroscopy.
• Better Resolution: Due to the multiple beam interference and the ability to adjust the cavity length precisely, Fabry-Perot interferometers can achieve higher spectral resolution. This makes them better suited for applications requiring the analysis of closely spaced spectral lines.
• Greater Sensitivity: The design of Fabry-Perot interferometers allows for a longer effective optical path difference, which enhances their sensitivity to changes in optical path length. This is particularly useful in applications like precision metrology and narrow linewidth measurements.

Advantages of Michelson Interferometer

• Flexibility: Michelson interferometers are known for their versatility and flexibility in various experimental setups. They can be easily adapted for different types of measurements, including Fourier-transform infrared spectroscopy (FTIR).
• Simpler Design: The design of Michelson interferometers is generally simpler and more straightforward, making them easier to construct and maintain.
• Broad Application Range: Michelson interferometers are not limited to high-resolution spectroscopy and can be used in a wide range of applications, including optical coherence tomography (OCT) and general interferometric measurements.

Conclusion

While both interferometers have their unique advantages, the Fabry-Perot interferometer is often preferred for applications requiring higher resolution and sensitivity due to its ability to produce sharper interference fringes and its higher finesse. However, the choice between a Fabry-Perot and a Michelson interferometer ultimately depends on the specific requirements of the application, including the desired resolution, sensitivity, and experimental flexibility.