Essay on Laser Torch

8132 Words Sep 27th, 2011 33 Pages
MAJOR PROJECT LASER TORCH BASED VOICE TRANSMITTER AND RECEIVER

CHAPTER -1
INTRODUCTION 1.1 ABOUT PROJECT

LASER TORCH-BASED VOICE TRANSMITTER AND RECEIVER
Using this circuit you can communicate with your neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The phototransistor of the receiver must be accurately oriented towards the laser beam from the torch. If there is any obstruction in the path of the laser beam, no sound will be heard from the receiver. The transmitter circuit comprises condenser microphone transistor amplifier BC548 (T1) followed by an opamp stage built around µA741 (IC1). The gain of
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Physicists Charles H. Townes and his brother-in-law Arthur Schawlow were the first to actually apply for a patent on the laser and they were the first to publish their findings in scientific journals. The He-Ne laser (red beam) was in commercial use, by 1968. Today many different types of lasers exist, for a wide range of applications. Lasers are used for surgery, for cutting metal, for determining distance, for projecting 3-dimensional holographic images, for computer printing and for entertainment lighting applications. Laser light differs from ordinary light in four ways. Briefly it is much more intense, directional, monochromatic and coherent. Most lasers consist of a column of active material with a partly reflecting mirror at one end and a fully reflecting mirror at the other. The active material can be solid (ruby crystal), liquid or gas (HeNe, CO2 etc.).

1.22 Why use a laser? A laser as a communications medium has some unique properties compared to other forms of media. A line-of-sight laser beam is useful where wires cannot be physically connected to a remote location. A laser beam, unlike wires, also does not require special shielding over longer distances. Lasers offer at least an order of magnitude longer distances compared to infrared LEDs. Although RF

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