Photodiode Daylight elimination

[chippevijaya]

Dear friends,
I am developing a IR Laser receiver. for that i have chosen QSD2030F photo-diode(Peak sensitivity λ = 880nm, and specified daylight filter), from fairchild, And i have connected this to a high speed transimpedance amplifier, opa380.

Here the problem comes in picture, whenever i have taken this module to outdoor environment, under sunlight, there is a dc-offset and it is completely high(up to 5VDC, entire is working on 5V). So i am unable capture the pulses of laser that fired on it. the QSD2030F is showing having daylight filter option, but it is not working under daylight.

In indoor condition the DC-offset is as low as, i can capture the pulses.

Is there any idea that to eliminate the daylight effects, and my module will work under sunlight.

Please help me...

 

[(*steve*)]

Investigate a magic component which blocks DC yet allows an AC signal to pass...

 

[JMW]

Early heat seeking guided missiles suffered from the same problem. They would lose lock on the target and target the sun.

 

[chippevijaya]

Investigate a magic component which blocks DC yet allows an AC signal to pass...

thanks for your suggestion steve

 

[glewis721]

so from what i understand the sunlight is so bright thar it is over-riding the laser pulses, no? well if that is the case, then mabe you could build some sort of sunlight shield, like a sun visor.

or if than doesn't work you could make a box aroundthe reciver, and leave a hole in the side that is just large enough for the laser to shine through.

hope this helps! =D

 

[chippevijaya]

so from what i understand the sunlight is so bright thar it is over-riding the laser pulses, no? well if that is the case, then mabe you could build some sort of sunlight shield, like a sun visor.

or if than doesn't work you could make a box aroundthe reciver, and leave a hole in the side that is just large enough for the laser to shine through.

hope this helps! =D

Thank you, i did this by using particular wavelength filter. It works well under sunlight, but it is more expensive(approx 200$). I don' want to use this, for that i choose the photo-diode with built-in daylight filter(somehow better than normal photo-diodes, but under direct sun all are one) i am experimenting on it.

 

[(*steve*)]

If my first suggestion wasn't helpful, consider seeing if you can select an appropriate biasing for use in bright sunlight.

Once you've determined that, see if you can make this value determined by the average of the recent ambient light levels.

 

[chippevijaya]

If my first suggestion wasn't helpful, consider seeing if you can select an appropriate biasing for use in bright sunlight.

Once you've determined that, see if you can make this value determined by the average of the recent ambient light levels.

Steve, appropriate biasing for what case either photodiode or amplifier. will you explain me clearly.

I think i achieved a step in this problem, i have connected photodiode cathode to 5V and anode to transimpedance amplifier, a variable resistor other end grounded, a capacitor other end grounded. with the help of this adjusting resistor i can adjust the dc-offset of the daylight output to near by zero, my guess the dark current are reducing.
But still need to work to make my sensor to work in all types of sunlight(day-dawn-dusk).

 

[(*steve*)]

Draw a circuit diagram of what you have now.

 

[chippevijaya]

Draw a circuit diagram of what you have now.

Here you find the attachment,

 

[(*steve*)]

Why is the capacitor there?

Wouldn't it be better to AC couple your signal?

 

[chippevijaya]

Photodiode Amplifier problem

Dear friends,
I am trying to develop a photodiode receiver circuit as shown in figure. When i placed this in under sunlight the output voltage level is shifted(DC-offset) is happening.
Is there any possibility to reduce the offset of the voltage and try to pull near to zero. This is happening due to photodiode is receiving the sunlight components and turned to high.
Please help me in this.

 

[(*steve*)]

The answer was given in post number 2 and amplified in post number 11.

Please don't start multiple threads for the same problem.

 

[chippevijaya]

Why is the capacitor there?

Wouldn't it be better to AC couple your signal?

Capacitor is just for fine pulse shape.....
It is not that much important...

Can you a have any circuit idea to solve the level shift in signal....

 

[chippevijaya]

The answer was given in post number 2 and amplified in post number 11.

Please don't start multiple threads for the same problem.

Both the threads are different, see the questions one is for daylight elimination and other is to remove level shift in op-amp.....if anyone solved it will help in solving my problem.
And try to understand problem and give any solutions, thats why i am posting in forums.

 

[(*steve*)]

They are both the same problem.

signal source -- capacitor -- amplifier

This fixes both (I say both...)

Note that you may need to provide a DC bias for the input of your amplifier