Power Loss From Lens/Collimator on 5mw 650nm?

[shoo]

Newbie here. I searched the forums, but could not find an answer to what I think is a simple question.

Anybody know roughly how much more light output you get by removing the lens/collimator on a cheapy 5mW 650nm laser diode, such as those from AixiZ? Understanding that the light will be unfocused without the lens, does the lens absorb only a few percent or does it cut the light output by like half?

Bonus question, I read that removing the lens can actually cause the diode to use too much power and burn out because the feedback from the lens is missing. Is this right?

Thanks a million!
Shoo

 

[Krogith]

Newbie here. I searched the forums, but could not find an answer to what I think is a simple question.

Anybody know roughly how much more light output you get by removing the lens/collimator on a cheapy 5mW 650nm laser diode, such as those from AixiZ? Understanding that the light will be unfocused without the lens, does the lens absorb only a few percent or does it cut the light output by like half?

Bonus question, I read that removing the lens can actually cause the diode to use too much power and burn out because the feedback from the lens is missing. Is this right?

Thanks a million!
Shoo

Leave your lens alone.

No the diode wont burn out it will just be a uncollimated beam

Welcome to LPF

 

[jakeGT]

Without collimating you so realize it's more like a flashlight... There will be no beam or "dot" at all

 

[3zuli]

Anybody know roughly how much more light output you get by removing the lens/collimator on a cheapy 5mW 650nm laser diode, such as those from AixiZ?

you'll probably get only few % more output. but you will not see the difference by eye... these calculations are useful only with higher powers (>300mW)

Bonus question, I read that removing the lens can actually cause the diode to use too much power and burn out because the feedback from the lens is missing. Is this right?

that's not true. if the diode gets too much light reflected back to it, it will die. the less reflected light, the better for the diode
or it could be theoretically true if the driver was using the feedback from photodiode inside the laser diode, but today most of the drivers are just plain current regulators without any feedbacks

 

[shoo]

Thanks for the replies thus far.

As for the change in light output by removing the lens. I found a test on the internet that indicated the lens on the cheapy 5mW 650nm laser diodes reduces the light output by 30-40%. Has anyone here tested it? Can anyone confirm that figure?

Also, to the extent it wasn't clear, I understand that removing the lens turns the laser into an unfocused light.

As for the bonus question, I went back to where I read that removing the lens cause problems. And 3zuli, you were correct. The laser in question had a feedback component to the driver. It sounds like that is not applicable on the cheap 650nm diodes.