Fineness of Etalon

Etalon fineness and free spectral range
Calculator of Fineness for Etalon

Parameter calc.

Transmission curve

Program info

Main formulas

References

1. CW laser wavelength: nm
Angle to etalon: deg

2. Etalon material:
Single-surface intensity reflectance:
Thickness: mm

1. CW laser wavelength: nm

2. Etalon material:
Single-surface intensity reflectance:
Thickness: mm

3. Incident angle 1: deg
Incident angle 2: deg

Output calculated data

This program is used to calculate etalon fineness and laser intensity transmission.
Function 1: For a single set of laser/etalon parameters, calculate fineness, intensity transmission, spectral FWHM, angular resolving power, spectral resolving power, and free spectral range.
Function 2: Calculate intensity transmission as the etalon is rotated and plot the curve to show the trend.

Tip: Use the tabs above to calculate and view related information.

1. Etalon intensity transmission:

$$T = \frac{1}{1+F\sin^2\frac{\delta}{2}}$$

Where $$F=\frac{4R}{(1-R)^2},\delta=\frac{4\pi}{\lambda}nL\cos\theta=2\pi m,\frac{\sin\gamma}{\sin\theta}=n$$ n is the refractive index of the etalon, R is the single-surface intensity reflectance, L is the thickness, $\lambda$ is the wavelength, $\gamma$ is the incident angle, and m is the interference order.
2. Etalon fineness:

$$FNS=\frac{\pi\sqrt{R}}{1-R}$$

3. Spectral FWHM of a transmission peak:

$$\Delta\lambda_m=\frac{\lambda}{m\cdot FNS}$$

4. Angular resolving power:

$$D_{\theta}=\frac{\delta\theta}{\delta\lambda}=-\frac{m}{2nL\sin\theta}=-\frac{m}{2L\sin\gamma}$$

5. Spectral resolving power:

$$A=m\cdot FNS$$

6. Free spectral range:

$$FSR=\frac{\lambda}{m}$$

[1] Lüzhong Cai et al., Optics, pp. 170-179.

Finesse and Free Spectral Range of an Etalon