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DTR BDR-209 405nm Laser Diode shows a blurry square light.

rajhlinux

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Hello guys,

So I was finally able to power up the laser diode from DTR.
I got two of these modules.
It is a "900mW 405nm Blu-Ray BDR-209 Laser Diode In Copper Module W/Leads & G-2 Glas Lens":

IMG_6548.jpg


I have the IC-Haus IC-HKB-S08-TP laser driver chips but for testing purposes of the laser module,
I'm using an ordinary laser driver found on Amazon:

IMG_0006.jpeg


I was extremally careful to preset the driver voltage and current around 3 volts and 20mA. I then hooked up the laser module to the laser driver:

IMG_00055.jpg


For some reason when I focus the laser light, I get a tiny dot along with a blurry square emission of light:

IMG_0004.JPEG


I cleaned the DTR G2 AR coated lens with mild soapy water with a cotton swap and dried it with a cotton swap and still the same results like above.

Here is a video for a better explanation:

What am I doing wrong that is causing the focused laser light to produce a tiny beam spot along with a squarish light emission?

Thanks for any advice.
 



RA_pierce

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1. The diode is being driven near or below lasing threshold if you are powering it with 3V and 20mA. When diodes are driven below their operating parameters, you often get weird looking beams. You will get a much nicer beam when you give it the power it needs. This diode is capable of exceeding 500 mW output but I think it is designed for somewhere around 200 mW. That would mean it's operating voltage is somewhere around 5.5 V and probably wants something like 200 mA. Please DO NOT quote me on those numbers. I'm giving an estimate based on nothing but a little bit of experience.

2. The single-mode violet, blue, and green diodes are known to produce a rectangular artifact in the output. This is particularly noticeable with short focal length collimators like the G-2 lens. A longer focal length lens like the G-8 will hide this artifact a little better. It cannot be eliminated completely without implementing some beam correction elements (like spatial filtering).
 

rajhlinux

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1. The diode is being driven near or below lasing threshold if you are powering it with 3V and 20mA. When diodes are driven below their operating parameters, you often get weird looking beams. You will get a much nicer beam when you give it the power it needs. This diode is capable of exceeding 500 mW output but I think it is designed for somewhere around 200 mW. That would mean it's operating voltage is somewhere around 5.5 V and probably wants something like 200 mA. Please DO NOT quote me on those numbers. I'm giving an estimate based on nothing but a little bit of experience.

2. The single-mode violet, blue, and green diodes are known to produce a rectangular artifact in the output. This is particularly noticeable with short focal length collimators like the G-2 lens. A longer focal length lens like the G-8 will hide this artifact a little better. It cannot be eliminated completely without implementing some beam correction elements (like spatial filtering).

Thank You for the helpful tip.
 

Unown (WILD)

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That diode can hit over 1W no?
Only if you don't mind popping it in a short amount of time. Whoo boy those diodes are sensitive as heck too. Every one I've owned were under driven and they still burned out. So I gave up on it long ago
 

rajhlinux

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So I drove the laser at 5.2 volts and around 220mA, still the same results.
You can't really see the box artifact because the iPhone 6S Plus camera sensor is too sensitive even behind laser googles, but you can still see the artifact around position 5 O'clock and 6 O'clock.

It's really terrible artifact, much worse than the cheapo eBay laser pointers that are 50mA with 405nm. I never seen such bad artifacts like these before on a laser.
I also asked someone who is an expert in this field and he told me that the laser diodes are possibly damaged and usually produce these artifacts.

Note: I wasn't using any TTL/PWM pulses, I just hooked it up to the laser driver.
I did preset the voltage and current settings then hooked up the laser diodes, I was extremely careful to not damage the laser modules.

Thinking to return these diodes.

Here is the video:
 
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rajhlinux

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RA_pierce

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It's really terrible artifact, much worse than the cheapo eBay laser pointers that are 50mA with 405nm. I never seen such bad artifacts like these before on a laser.
I also asked someone who is highly knowledgably in this field and he told me that the laser diodes are possibly damaged and usually produce these artifacts.
This sounds likely. Did the output power increase with the increase in input power?

Perhaps someone more knowledgeable in the subject of electronics will be able to make an assessment regarding whether the power source might have caused a problem...
 

rajhlinux

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Only if you don't mind popping it in a short amount of time. Whoo boy those diodes are sensitive as heck too. Every one I've owned were under driven and they still burned out. So I gave up on it long ago

Yeap thats true, laser diodes are really sensitive, best to under drive them. But wow they pop even under driven really sucks.
 

rajhlinux

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This sounds likely. Did the output power increase with the increase in input power?

Perhaps someone more knowledgeable in the subject of electronics will be able to make an assessment regarding whether the power source might have caused a problem...

That's the weird part, the laser modules was increasing the output while I increase it's current and voltage.
It was extremely dumb bright lol. Wearing laser goggles was a must.
 

RA_pierce

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The surface you are projecting the beam onto is fluorescent. This will make it appear much brighter.
You may be able to get a better idea of the beam profile on a non-fluorescent matte black surface (preferably something that won't burn).

I took another look at your first video and when you adjust the focus of the lens, it does look like the profile of a damaged diode.
 

Wakrah

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Is it possible your lens is in backwards? Not likely, I know, but in the past I've seen complaints a beam could not be focused to a point for that reason here.
 

rajhlinux

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The surface you are projecting the beam onto is fluorescent. This will make it appear much brighter.
You may be able to get a better idea of the beam profile on a non-fluorescent matte black surface (preferably something that won't burn).

I took another look at your first video and when you adjust the focus of the lens, it does look like the profile of a damaged diode.

That is true, but with white paper I can see the true beam profile for leaking artifacts.
I'll be using this laser diode for exposing PCB photoresist material. Any hint of leakage of UV light will expose the UV sensitive material.
 

rajhlinux

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Try another lens, the G2 is a piece of shit. Tried it on several modules and it just makes a messy blob. G8 looks better but still has artifacts and fits like shit (too loose/sloppy).
Also, you can ruin your diode by underpowering it or simply just changing to power load to it. Careful, this is low quality flea market shit your dealing with here...

Alright
 




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