can anyone plz teach me how to interface a LASER diode with microcontroller . The LASER diode will be used to transmit the output data(in binary format)of microcontroller using an optical fiber .... plz reply asap .... thanx for reading this and for your help .....
nobody can answer based on the scant info you give what current needed what micro
Ignore that it is a LASER (by the way, even if "LASER" might stand for Light Amplification by Stimulated Emission of Radiation, the word "laser" has been added to the dictionary since quite a number of years), and instead concentrate on what it requires.
What is the expected voltage? What current? What transfer rate, i.e. how quickly must you be able to turn on/off the drive? A very important thing here is if it has a digital signal intended to modulate it, or if it is a raw LED diode where you are responsible for the exact drive current, or if you are going to turn on/off a power-converter that will produce the specific drive current.
... and understand what your microcontroller can provide.
Marrying the two is the essence of Interfacing anything to anything else: www.8052.com/.../160143
microcontroller used will be 8051.. currentnot to exceed 200 mA and 5 volts ...... plz tell me your email id so that i can breif u about my project.. have to complete this job in this month only .... i will be greatfull for your considerations ..... thanx
WIth your reply and Per Westermark questions, I also want to add one more question here,
Question: 1. What is the distance of source and destination if you are using fiber optic??
Important point: 1. By seeing your current rating, you can't directly connect laser to 8051 IOs, since 8051 can't pump that much of current, so you have to use buffer to boost up the signal.
- I can help you with hardware as well as software, if it is not confidential.
it would be an oppurtunity to learn it from u sir ... the project is not at all confidential ..... the length of optical fiber will not exceed more den 3 mtrs... my email id is ::-> kingtutrocks9891284125@gmail.com plz mail me your suggestions .....
I mailed you, reply to the mail for further clarifications.
Note that it isn't just a question of being able to supply 200 mA, so it isn't enough to have a more powerful buffer chip or transistor.
A laser wants a regulated current, compared to much other equipment that wants a regulatd voltage. A switching transistor just supply or remove supply of a voltage, but leaves it to the consumer to draw as much as it wants/needs at that voltage. A laser needs a current-limiting circuit where you adjust the drive current to how powerful the laser is. That's one of the reasons why so many lasers comes with a little driver board.
Constant current can't be managed by just carefully adjusting the voltage. A minute change to the voltage will result in a huge change in current. And a tiny temperature change will result in a minute change to the voltage of a voltage regulator, resulting in a huge change of current.
So let's repeat the question I asked before. Is this a naked laser diode, where 200 mA is the maximum current allowed or a diode + drive electronics where 200 mA is the maximum current needed?
If it's a naked laser LED, then it does require that the processor turns on/off the power from a constant-current generator, i.e. a circuit with a feedback loop where the voltage gets dynamically adjusted to keep the current stable. Or alternatively - that the laser is driven like a normal LED with a constant voltage and a series resistor, where the resistor is selected so the laser will never manage to draw more than 200 mA. If using a series resistor, then the design must allow enough voltage to burn over the resistor to make it reasonably stable - if too little percent of the total voltage gets burned over the resistor, then a small change in supply voltage will result in a significant change in laser current.
You are not TEXTING or TELEGRAPHING, use English WORDS, spell them correctly and quit the excessive use of PERIODS.
If you bastardize the language it makes it even more difficult for non-English speakers to translate it and communicate with you.
Jobs at US and UK companies will be hard to secure, for local or foreign applicants, if they write gibberish. Set yourself apart, write coherently, especially when communicating with people you don't know, or publicly.
Thanks for your attention.