PE-1100 LED and Diode laser

Topics:
  • Electro luminescence
  • Semiconductor
  • LED Light Emitting Diode
  • Laser Diode
  • Monochromatic Light
  • Coherence
  • Spatial Intensity Distribution
  • Beam Shaping
  • Cylindrical Lenses

PE-1100 LED and Diodelaser
PE-1100 LED and Diode laser

Nick Holonyak developed the first practical LED in 1962. When electrically biased in the forward direction an LED is able to emit light through electro luminescence. The color of the emission depends on the semi conducting material used, and can be near-ultraviolet, visible or infrared. The semi conducting chip is encased in a solid plastic lens, which is much more resistant than the glass envelope of a traditional light bulb or tube. Most typical LEDs are designed to operate with no more than 30-60 mill watts of electrical power. Around 2000, commercial LEDs capable of continuous use at one watt of input power were introduced. Nowadays 10 watt units will be available with efficiencies of 60 lumens per watt. These devices produce light similar to a 50 watt light bulb, and facilitate the use of LEDs for general illumination needs. The typical working lifetime of an LED is ten years, which is much longer than the lifetimes of most other light sources. Robert N. Hall is usually cited as the inventor of the semiconductor laser, but Holonyak was involved in the development as well. In laser diodes, light is generated basically on the same principle like in LEDs. But by especially designed semiconductor material laser operation is achieved rather than spontaneous luminescence. Within this experiment, properties of LEDs and Laser Diodes like current dependency, spectral and beam characteristics are investigated. The polarization state of the light emitted by the diodes is determined and beam shaping experiments are performed.
Set-up to measure the spatial intensity distribution A. Measuring the spatial intensity distribution
Set-up to measure the spectral intensity distribution
B. Measuring the spectral intensity distribution

In first experiments, the angular intensity distribution of the LED and the laser diode are measured. A photodiode is attached to the rotatable arm of a goniometer. The measured photo current is converted into a voltage and measured by the provided digital voltmeter. The light source is placed as close as possible to the pivot point of the goniometer.
It will be noted, that the emission of the laser diode has an elliptical beam profile. By rotating the diode laser in the adjustment holder the profile can be measured for both the vertical and horizontal direction. The subsequent experiments are used to study the spectral emission of the provided light sources.
For this, the emitted radiation of the light source illuminates the adjustable slit. The image of the slit is projected by means of the imaging lens to the image screen which is fixed to the goniometer arm.
After passing the grating the incident light is divided into multiple orders and the spectral distribution becomes visible as vertical bars (line), the image of the slit. The intensity of the image on the screen depends on the adjusted width of the slit. Closely neighbored lines may merge if the width of the slit is too wide.
PE-1100 LED and Diode laser, consisting of:
Item Code Qty. Description
1 CA-0220 1 Multimeter 3 1/2 digits
2 DC-0120 1 Si-PIN Photodetector, BPX61
3 DC-0380 1 Photodetector Junction Box ZB1
4 LQ-0060 1 Red (635 nm) diode laser in ø 25 housing
5 LQ-0200 1 White LED in ø 25 Housing
6 LQ-0210 1 Red LED in ø 25 housing
7 LQ-0230 1 Blue LED in ø 25 housing
8 MM-0020 2 Mounting plate C25 on carrier MG20
9 MM-0038 1 Mounting plate C30-V on carrier MG20
10 MM-0110 1 Translucent screen on carrier MG20
11 MM-0240 1 Adjustable slit on carrier 20 mm
12 MM-0300 1 Carrier with 360° rotary arm
13 MM-0450 1 XY Adjustment holder with rotary insert on MG20
14 MP-0150 1 Optical Bench MG-65, 500 mm
15 MP-0220 1 White screen with XY scale on block
16 OC-0140 1 Achromat f=40 mm in C30 mount
17 OC-0220 1 Cylindrical lens f = 20 mm in C25 mount
18 OC-0280 1 Cylindrical lens f=80 mm in C25 mount
19 OC-0460 1 Transmission grating 600 l/mm
20 UM-PE11 1 Manual LED and Laser Diode
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