Lasered Security System

REQUIREMENTS:

Laser module
LDR(light dependent resistance) module
AT89S52 (8051 microcontroller by ATMEL Corp.)
11.0592 MHz crystal
(for indication)

Prototype of 8051 Microcontroller based Laser Security System

Fig. 1: Prototype of 8051 Microcontroller based Laser Security System

DESCRIPTION:

This system for security uses the combination of LASER light and LDR. The LDR module has an onboard potentiometer to adjust the sensitivity of LDR, so that it only senses laser light falling onto it.

The concept is quite simple and similar to what we see in movies where antique, priceless ornaments are protected under laser lights.

As someone crosses these lights, an alarm runs on to indicate unauthorised presence. This project works similarly.

In normal conditions, where there is always laser light falling on the LDR, the LDR module always gives a high signal to microcontroller.

When someone crosses this laser light, it will behave as an obstruction between the LDR module and laser light, resulting in no light falling on LDR. In such cases LDR module gives a low signal to the microcontroller, which indicates it to switch on an alarm (or LED in this case).

Here I am using only a pair of LDR and LASER module.

But for better and efficient security results, a group of such LASER and LDR modules can be used simultaneously.

We can also use only one laser light with an optical system which will scatter light on different LDR modules.

Diagram showing interception of LASER beam by an obstacle

Fig. 2: Diagram showing interception of LASER beam by an obstacle

Diagram showing interception of LASER beam by an intruder

Fig. 3: Diagram showing interception of LASER beam by an intruder

Note:

This system will work only when it gets a continuous power supply therefore using a battery operated system won’t be a nice idea. I’ll suggest operating it with an AC-DC adapter for the desired results.

APPLICATIONS:

This system can also be used to count the no. of visitors and hence control something through this data.

It can be a very good replacement for the IR sensors I have used in my earlier project “AUTOMATIC ROOM LIGHTING”

It will enhance the effective distance (can be used for long range projects) and accuracy.

ADD-ONs:

We can add a LCD (16X2) for making it more user- friendly, in which it will tell us about the status of each and every particular sensor.

This can help us to secure thing more effectively and efficiently.

Project Source Code

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#include
sbit LDR=P1^0;
sbit LED=P1^1;
void main()
{
  LDR=1;
  LED=0;
  while(1)                                                                                                 {
        if(LDR==0)
        LED=0;
        if(LDR==1)
        LED=1;
      }                                                                                               
}

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