Detector Based Apparatus for

Diffraction Experiments

Model: HO-ED-D-02

This apparatus (Model No: HO-ED-D-02) is meant for graduate and post graduate level courses in physics. Here, the diffraction pattern is closely studied using a detector mounted on translation stage. The device consists of 1.2 meter long optical rail along with carriages, optics 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 measurement easy and convenient. Both the laser head and detector stages are mounted on rail carriages with locks, which in turn can be mounted anywhere on the rail conveniently.

In this apparatus, diffraction experiments are carried out with a photo sensitive detector and laser is used as light source. The diffraction element 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.

Experiment Examples

Diffraction of light by single slit

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

Diffraction of light by double slit

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

Diffraction of light by single wire

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

Diffraction of light by cross wire

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

Diffraction of light by wire mesh

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

Diffraction of light by transmission grating

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

Diffraction of light by circular aperture (Pinhole)

Radius of the Airy’s disc,

x   =   ( 1.22 l λ )   /   a

where,

a = Diameter of the aperture (pinhole),

l = Distance between the pinhole and the Screen,

λ = Wavelength of light,

x = Radius of the Airy’s disc

Thus we can find the diameter of the aperture (pinhole) using the equation

a   =   ( 1.22 l λ )   /   x

Related Topics

Single slit

Double slit

Single wire

Cross wire

Wire mesh

Transmission grating

Circular aperture (pin hole)
Features

High measurement accuracy, clear and sharp diffraction patterns

Diffraction elements are fixed to metallic casing for ease of mounting

Smooth switch on and long lifetime of light source

Reliable and affordable

Scope of Supply

Optical Rail

Model No: ED-D-02-OR
Length
:
1200 mm
Material
:
Black anodized Aluminum alloy
Quantity
:
1 no.

Kinematic Laser Mount

Model No: ED-D-02-KLM
Material
:
Black anodized Aluminum alloy
:
Using 80 tpi lead screws
:
+/-4 degrees
Quantity
:
1 no.

Cell Mount

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

Diffraction Cells

Model No: ED-D-02-DC
Single slit
:
50 & 100 micron
Double slit
:
100 & 200 micron
Transmission grating
:
30 lines / mm
Single wire
Cross wire
Wire mesh
Pinhole
Quantity
:
1 set.

Detector Mount with X- Translation

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

Detector Output Measurement Unit

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

Accessories

User Manual

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