Laser Control Circuit

The project mainly work to control the volt and limit the current entered to laser which is determine by the datasheet of used laser which is “laser diode 650nm” also read the current produced by the laser and display it on LCD (region of transimitter circuit ) then it also determine the current passing through photo diode which will used to calculate the output power but actullay this output must multiply by a specific factor to obey the general maximum power of laser which is at 950nm .

components:

LM317-Adjustable Voltage Regulator IC.

BC557-PNP Transistor.

Diode – 1N4007.

Resistor – (1k, 47k, 1).

Variable Resistor 5k.

Capacitor – (0.1uf, 22uf).

Arduino Nano.

LCD 2*16.

Adaptor 5v.

Breadboard.

3- circuits parts & role members:

The circuit of transmitter can be divided to two parts:

1- First one contain:

• Soft starter circuit

• Voltage regulator

• Heat sink

2- Second one contain:

• Write a code program for arduino

• Lcd display

Soft starter circuit:

A Soft Start Circuit prevents the sudden current flow in the circuit during the start. It slows down the rate of rising output voltage by minimizing the excess current flow during the start. It is useful to protect the devices or electronic components from the damage. Here we are building the soft start circuit using a voltage regulator IC LM317 and a PNP transistor BC557.

Arduino nano and LCD

we use an ATmega 328P microcontroller to Measurement of the out current of the laser :

- measures the volt in laser

- calculates the current that passes through the laser ( I = V/R )

- Read the analog value from the Laser.

- Convert the analog value to digital (binary).

- Send the binary data to the LCD display.

- LCD Display the received binary data.

- Light up according to the input from the Arduino board.

Receiver circuit:

• objective :

measuring the optical power using photodiode and displaying it on lcd using Arduino NANO (Atmega328P)

circuit diagram :

Required components :

• Photodiode (bpw34)

• Resistor 100 ohm

• 9 volt adaptor

• Arduino Nano

• Lcd (16x2)