This all the slides will help you to know the idea about the laser eavesdropping and the construction --keep support to my slides --Thanksyou

1. LASER EAVESDROPPING
By
S.PRADEEP, K.A.VIJAY
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
ERODE SENGUNTHAR ENGINEERING COLLEGE,ERODE

2. SYNOPSIS
 Introduction
 Laser Eavesdropping
 Construction
 Working
 Pros
 Cons
 Conclusion

3. LASER EAVESDROPPING
 Eavesdropping is the concept of hearing others conversation inside a room
secretly.
 Laser Eavesdropping is used as a spy device to hear the conversation
secretly and record it using a recording device.
 This is very useful to identify the sound for the particular distance.

4. COMPONENTS REQUIRED
The demonstration requires the following items:
 A typical classroom helium-neon laser
 A Photo cell
 An audio amplifier
 A speaker (headphones may be substituted)
 A 100-W portable stereo system
 A 2.2-mm thick pane of window glass

5. HELIUM-NEON LASER
A helium–neon laser or hence laser, is a type of gas laser whose gain medium
consists of a mixture of 85% helium and 15% neon inside of a small bore
capillary tube, usually excited by a dc electrical discharge. the best-known and
most widely used hence laser operates at a wavelength of 632.8 nm, in the red
part of the visible spectrum.
PHOTO CELL
Solar cell which is used to absorb the laser and it convert the light energy into
the electrical energy.
AUDIO AMPLIFIER
It amplifies the electrical signal from the disturbance to the audio signal.

6. SET UP OF THE MICROPHONE
 Place the Laser pointer in the tripod.
 Keep the laser pointer in the position that the laser light hits the window of the
place.
 The reflection of laser light must hit the photocell and connect the photocell
with headphone jack.
 Then finally connect it to the recording device.

7. (MIRROR)
BLOCK DIAGRAM
CONVERSATION
ROOM
LASER
PHOTO CELL
AUDIO
AMPLIFIER
SPEAKER

8. WORKING OF THE MODEL
 After the construction, when the people inside the room or place talk some vibrations
will be produced.
 The vibrations are absorbed by the laser beam that is being reflected to the photocell.
(WORKING MODEL)

9. CONDITION
 Then the photocell detects the light signal and converts it into audio signal.
 Now connect the photo cell with the headphone cable and give the connection
to the recording device.
 By this the conversation inside the room can be heard easily, amplifier and
filter can be added here for improving quality of audio.

10. PROS
 This technology can be used to eavesdrop with minimal chance of exposure
 By simple extrapolation it should be easily possible to adapt this technique
to a maser or focused microwave beam in order to bounce it off of internal
metal objects such as heating ducts or filing cabinets
 It is cost efficient
 User friendly

11. CONS
 If the interior of the structure is electromagnetically and acoustically isolated
then this wont happen
 If rippled glass can be used this method is invalid since it provides a poor
surfacing.
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12. WORKING MODEL