What Is the Fabry-Perot Interferometer Finesse & FSR Calculator?
A Fabry-Perot interferometer (or etalon) is an optical resonant cavity formed by two parallel reflecting surfaces.
How Does the Fabry-Perot Interferometer Finesse & FSR Calculator Work?
Multiple reflections interfere constructively only at integer multiples of half-wavelengths, producing sharp transmission fringes.
Fabry-Perot Interferometer Finesse & FSR Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
mathcal{F} = rac{pi sqrt{R}}{1 - R}, quad ext{FSR}_
u = rac{c}{2 n d}, quad Delta
u = rac{ ext{FSR}}{mathcal{F}}
Reflective finesse and cavity free spectral range frequency spacing.
How to Use the Fabry-Perot Interferometer Finesse & FSR Calculator
- Input mirror power reflectivity R, cavity spacing d, and laser wavelength.
Step-by-Step Example Calculation
Laser Spectroscopy Etalon
Input Values:
mirrorReflectivity:0.96
cavityLengthMm:15
centerWavelengthNm:1550
refractiveIndexMedium:1
Worked Steps: Yields Finesse = 76.9, FSR = 10.00 GHz (80.1 pm), and narrow resonance linewidth of 130.0 MHz.
Understanding Your Result
FSR is the frequency span between successive transmission peaks; finesse measures peak sharpness.
Factors That Affect the Result
- Mirror surface flatness imperfections, absorption losses, and mirror tilt reduce effective finesse.
When Should You Use This Calculator?
- Laser wavelength meter calibration, optical spectrum analyzers, tunable telecom filters, and gravitational wave detectors.
Assumptions & Limitations
- Assumes perfectly parallel, lossless mirrors and planar monochromatic wave incidence.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard Airy transmission distribution formulation.