Fabry - Perot Etalon

Model: HO-ED-INT-09

Holmarc's Fabry-Perot etalon is made of plate beamsplitters separated by 3mm distance. The beamsplitters are made by coating thin aluminum films on optically polished N-BK7 substrates. The reflecting surfaces are kept inside the assembly. The etalon has optical resonating properties similar to that of laser. A translucent screen is provided with vernier and needle to take the readings of the fringes directly.

Etalons transmit light as a series of periodic frequencies and their narrow bandwidth makes them well-suited for wavelength selection, measurement and line-narrowing. The properties of an etalon are largely determined by its thickness, index of refraction and the reflectivity of it’s surfaces. The finesse is a measure of the interferometer's ability to resolve closely spaced spectral lines.

An etalon is an optical interferometer in which a beam of light undergoes multiple reflections between two reflecting surfaces and it’s resulting optical transmission (or reflection) is periodic in wavelength. In other words, an etalon is a narrow band wavelength filter.

Experiment Examples

To find the Spacing of the Etalon

The Spacing of the Etalon is given by,

t  =  nD2λ  /  χn2

where n is the order, ‘D ’ is the distance between the etalon and the screen, ‘λ’ is the wavelength of light used.

χn2  =  χm+n2  -  χm2

χm+n2 is the square of the radius of (m+n)th ring and χm2 that of mth ring.

To find the Finesse and Free Spectral Range of the Etalon

The Free Spectral Range of the Etalon is given by,

FSR  =  c / 2t,

Where c is the speed of light in air and t is the spacing of the Etalon

The finesse is a measure of the interferometer's ability to resolve closely spaced spectral lines.

The finesse F is defined by the following equation.

F  =  π √R / ( 1-R )

Where, R is the reflectivity of surfaces

Fig. Schematic Diagram

Fig. Fabry Perot etalon produces sharp interference peeks

Features

Extended durability

Easy to operate

Precision design

Highly polished etalon
Related Topics

wavelength

Finesse

Free Spectral Range

Interference of light
Scope of Supply

Optical Rail

Model No: ED-INT-09-OR
Length
:
1000 mm
Material
:
Black anodized Aluminum alloy
Quantity
:
1 no.

Fabri-Perot Etalon

Model No: ED-INT-09-FPE
Material
:
N-BK7
Diameter
:
32 mm
Coating
:
Aluminium
R / T
:
60 : 40
Spacing of plates
:
3 +/- 1 mm
Quantity
:
1 no.

Kinematic Laser Mount

Model No: ED-INT-09-KLM
Material
:
Black anodized Aluminum alloy
:
Using 80 tpi lead screws
:
+/-4 degrees
Quantity
:
1 no.

Plano Convex Lens with Mount

Model No: ED-INT-09-PCLM
Material
:
N-BK7
Diameter
:
20 mm
Effective Focal Length
:
26 mm
Quantity
:
1 no.

Diode Laser with Power supply (Red)

Model No: ED-INT-09-DLPR
Wave length
:
650 nm
Optical power
:
5 mW
Quantity
:
1 no.

Diffuser Screen with Measurement unit

Model No: ED-INT-09-DSM
Material
:
Float
Size
:
150 x 138 x 3 mm
Quantity
:
1 no.

Accessories

Allen Key
User Manual
Tuning Knobs