Single Slit Diffraction and

Heisenberg’s uncertainty principle

Model: HO-ED-D-02A

Holmarc's Apparatus Model HO-ED-D-02A is meant for the study of diffraction patterns of single slits and to confirm Heisenberg’s uncertainty principle. Here, the diffraction pattern is closely studied using a detector mounted on a translation stage. The device consists of one meter long optical rail along with carriages and opto-mechanics. At one end of the rail, X-translation stage with detector is mounted and at the other end, laser is held on a kinematic mount. Linear scale attached to the rail makes length measurements easy and convenient.

In this apparatus, diffraction experiments using single slits are carried out with a photo sensitive detector and diode laser is used as light source. The diffraction slit is placed at a certain distance from the detector and the pattern is allowed to fall on the detector stage. The micrometer driven stage is used to move the detector to extreme end of the diffraction pattern and the intensity is noted at close intervals by traversing the detector through the cross section of the spectrum. The intensity versus distance curve is plotted on a graph for calculations. The results are evaluated both from the diffraction pattern viewpoint, and from the quantum mechanics stand- point to confirm Heisenberg's uncertainty principle. Thus this apparatus clearly reveals that the narrow slit produces a broader momentum distribution. This confirms the Heisenberg’s uncertainty principle in a single slit diffraction.

Experiment Examples

To observe the diffraction pattern and calculate the slit width

The diffraction equation (condition for minima) is,

Sin θm   =   m λ   /   d

Where d is the slit width, m is the order, λ is the wavelength of laser used and θm is the angle subtended within the central maximum and mth order minimum.

From this we can find out the slit width d as

d   =   m λ   /   Sin θm

To calculate the uncertainty of momentum from the diffraction patterns of single slits of differing widths and to confirm Heisenberg’s uncertainty principle

The diffraction equation (condition for maxima) is,

Sin θm   =   m λ   /   d

Where d is the slit width, m is the order, λ is the wavelength of laser used and θm is the angle subtended within the central maximum and mth order minimum.

From this we can find out the slit width d as

d   =   m λ   /   Sin θm

Specifications

Optical Rail Length  :  1000 mm

Diode Laser Wavelength  :  650 nm

Detector Sensor range  :  0-199 milli / micro amperes

Detector Mount linear travel  :  25mm

Slit  :  Width=50,100,150,200 microns

Scope of Supply

Optical Rail

Model No: ED-D-02A-OR
Length
:
1000 mm
Material
:
Black anodized Aluminum alloy
Quantity
:
1 no.

Kinematic Laser Mount

Model No: ED-D-02A-KLM
Material
:
Black anodized Aluminum alloy
:
:
+/-4 degrees
Quantity
:
1 no.

Cell Mount

Model No: ED-D-02A-CM
Material
:
Black anodized Aluminum alloy
Diameter
:
30 mm
Quantity
:
1 no.

Diffraction Cells

Model No: ED-D-02A-DC
Single slit
:
50, 100, 150, 200 micron
Diameter
:
30 mm
Quantity
:
4 Nos.

Detector Mount with X- Translation

Model No: ED-D-02A-DMX
Material
:
Black anodized Aluminum alloy
Travel
:
Micrometer controlled
Resolution
:
0.01 mm
Diameter
:
30 mm
Quantity
:
1 no.

Diode Laser with Power supply (Red)

Model No: ED-D-02A-DLPR
Wave length
:
650 nm
Optical power
:
3 mW
Quantity
:
1 no.

Detector Output Measurement Unit

Model No: ED-D-02A-DOMU
Sensor Type
:
Photo Transistor
Display
:
7 segment, 3 ½ digit
Range
:
0 - 199 milli / micro amperes
Quantity
:
1 no.

Accessories

User Manual