Michelson Interferometer

(Sodium D’ Lines)

Model: HO-ED-INT-06S

In this model of Michelson interferometer, sodium vapor lamp is used as light source. Sodium has two emission wavelengths that have extremely close values and without sensitive equipment, it cannot be distinguished. Measurement of these lines, designated as D1 and D2 Fraunhofer lines, the average wavelength as well as difference between the two emission lines of sodium can be determined. The purpose of this experiment is to measure the wavelength of Sodium D emission lines.

The two beams of a Michelson interferometer interfere constructively when the waves add in phase and destructively when they add out of phase, producing circular interference fringes as a result. From this we can calculate wavelength of sodium source. The interference pattern observed with the sodium lamp contains two sets of fringes which disappear when the bright bands of one set are superimposed on the dark bands of the other. The wavelength separation of the Na D-line doublet is easily determined by observing the successive coincidence and discordance of the two sets of fringe systems produced by the doublet of wavelengths (λ1 and λ2 with λ1 > λ2 ). As D is increased, the two systems gradually separate and the maximum discordance occurs when the rings of one system are set exactly halfway between those of the other system. The discordance positions are most clearly seen as minima in the contrast of the pattern.

Experiment Examples

To find out the difference in wavelength of D1 and D2 lines of sodium light

Wavelength separation  λ1 - λ2  =  λ2 / 2D

where λ is the average wavelength of the sodium and D is the change in position of the micrometer for two successive discordance / coincidence.

To determine the wavelength of monochromatic light

The wavelength of laser is calculated by;

λ  =  (2d / N) Δ

where ‘d’ is the change in position that occurs for ‘N’ fringes to pass and Δ is the calibration constant of the micrometer

To measure refractive index of transparent materials

The light passes through a greater length of glass as the plate is rotated. The change in the path length of the light beam as the glass plate is rotated and relates the change in path length with the laser beam through air.

The refractive index of glass slide,

N  =  (2t - Nλ)  (1- cos θ)  /  2t (1-cos θ)  -  Nλ

Where t is the thickness of the glass slide, N is the number of fringes counted, λ is the wave length of light used and θ is the angle turned for N fringes.

Features

Sodium vapor lamp and diode laser is used

CCD camera is used

Computer interfaced

Mirrors and beamsplitter are mounted on precision kinematic mounts for fine tuning and alignment

Related Topics

Interference of light

Refractive index

Wavelength

D1 and D2 Fraunhofer lines
Scope of Supply

Model No: ED-INT-06S-BBS
Dimensions
:
800mm x 600mm
Material
:
Stainless Steel
Quantity
:
1 no.

Kinematic Laser Mount

Model No: ED-INT-06S-KLM
Material
:
Black anodized Aluminum alloy
:
:
+/-4 degrees
Quantity
:
1 no.

Beamsplitter Mount

Model No: ED-INT-06S-BSM
Degrees of freedom
:
2 degrees
Material
:
Black anodized Aluminium alloy
Quantity
:
1 no.

Mirror Mount with Translation

Model No: ED-INT-06S-MMT
Degrees of freedom
:
3 degrees
Course movement
:
Micrometer controlled
Least count of the micrometer
:
0.01 mm
Material
:
Black anodized Aluminium alloy
Quantity
:
1 no.

Mirror Mount with Precision Translation

Model No: ED-INT-06S-MMPT
Degrees of freedom
:
3 degrees
Material
:
Black anodized Aluminium alloy
Least count of the micrometer
:
0.01 mm
Quantity
:
1 no.

Rotation Stage

Model No: ED-INT-06S-RS
Resolution
:
2° / division
Material
:
Black anodized Aluminium alloy
Quantity
:
1 no.

Camera lens Assembly Mount

Model No: ED-INT-06S-CLAM
Diameter
:
50 mm
Material
:
Black anodized Aluminium alloy
Quantity
:
1 no.

Camera Lens Assembly

Model No: ED-INT-06S-CLA
Focal length
:
65 mm
Quantity
:
1 no.

Diffuser plate with Mount

Model No: ED-INT-06S-DPM
Plate Diameter
:
25 mm
Material
:
Borofloat
Quantity
:
2 nos.

Beamsplitter

Model No: ED-INT-06S-BS
Dimension
:
50 mm x 50 mm
Thickness
:
4 mm
R / T ratio
:
50 / 50
Material
:
N-BK7
Coating
:
Aluminium
Quantity
:
1 no.

Mirror with Cell

Model No: ED-INT-06S-MC
Diameter
:
25 mm
Thickness
:
6 mm
Material
:
Borofloat
Coating
:
Aluminium
Quantity
:
2 nos.

Glass Slide

Model No: ED-INT-06-GS
Dimension
:
75 mm x 25 mm
Thickness
:
1 mm
Material
:
Float
Quantity
:
5 nos.

Diode Laser with Power supply (Red)

Model No: ED-INT-06S-DLPR
Wave length
:
650 nm
Optical power
:
5 mW
Quantity
:
1 no.

Sodium vapor lamp with Power Supply

Model No: ED-INT-06S-SLPS
Output Power
:
35 W
Quantity
:
1 no.

CCD Camera

Model No: ED-INT-06S-CCDC
Resolution
:
Selectable (320-1280 pixels)
Connectivity
:
USB 2.0
Quantity
:
1 no.

Accessories

User Manual
Allen keys
Thumb Screws
Dust Protective Cover
Net book (Optional)

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