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Is there a way to stop a DPSS 532nm laser (0.9watt) from flickering as in the attached short clip?

lasermore

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Is there a way to stop a DPSS 532nm laser (0.9watt) from flickering
as in the attached short clip? It is about a 5Hz flicker of significant
intensity-magnitude. Full-disclosure -- it is running off of an
5volt-adapter connected to a power-inverter which is connected to a
12volt car battery. The distance to the laser is 0.34miles.
Below is a gif-video of the flickering. I can tolerate some small flickering,
but my application needs the beam to be primarily steady, not flickering like this.
 
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Immo1282

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8volt-adapter connected to a power-inverter which is connected to a
12volt car battery
Flickering aside - this is a silly way to power the laser... 12VDC -> 110/230VAC -> 8VDC is madness - get/build a DC-DC converter or linear regulator to drop the DC voltage from 12V to 8V - this'll be way more efficient and far simpler overall.

If you're running it from a car battery - does that mean you're running the car engine at the same time? If so, could it be vibrations from the car? Does the laser flicker close up - cause if there's no visible intensity flicker close up, I'd guess something physical either moving the laser or interfering with the beam. A column of hot rising air perhaps?
 

lasermore

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Flickering aside - this is a silly way to power the laser... 12VDC -> 110/230VAC -> 8VDC is madness - get/build a DC-DC converter or linear regulator to drop the DC voltage from 12V to 8V - this'll be way more efficient and far simpler overall.

If you're running it from a car battery - does that mean you're running the car engine at the same time? If so, could it be vibrations from the car? Does the laser flicker close up - cause if there's no visible intensity flicker close up, I'd guess something physical either moving the laser or interfering with the beam. A column of hot rising air perhaps?
The car engine was running. But, there is quite a long extension cord from the inverter to the laser. The laser itself should be pretty steady. You can see its reflection-center-point is not moving, in the 2nd clip. I can drop the voltage myself, but at the moment it was a quick way
to be able to turn the laser on/off from 0.34miles away with a remote-push-button on the inverter.
Could there be hot-air rising -- I suppose. But the 5Hz flickering continues on and on and on for three consecutive minutes irregardless of the wind-gusts, etc. I think it is the laser or power-electronics creating the 5Hz 'pulsing' -- I just don't know how/why at this point.
ps: I will look into whether there is close-up pulsing and get back on that point.

Later I checked:
When I shine the laser on the wall in my house, I can't truly say I see any pulsing in any of the three modus operandi:
1. 8v adapter directly into house AC-socket.
2. 8v adapter into inverter into 12v car battery without the engine running.
3. 8v adapter into inverter into 12v car battery with the engine running.

--In all three cases I am just looking at the laser reflection (with safety glasses on).
 
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hakzaw1

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double post
plz edit/ copy / dele/ edit/ paste/save
no back to back posting
 

Immo1282

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double post
plz edit/ copy / dele/ edit/ paste/save
no back to back posting
Might have posted this on the wrong thread Hak?

Could be a bad laser? Have you contacted the company you purchased it from for advice and a possible replacement if that ends up being the outcome?
 

Alaskan

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My questions are whether you see the flicker close up or not, and is the laser mounted on a car or something vibrating? If it's flickering close up, check your DC power supply output, maybe the inverter is inducing ripples on the DC power supply output into the laser.
 
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smallfreak

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What I see in this "videos" especially the second one ist not "flicker" of the Laser, but the result of the large air space between the source and the target. Let me guess - there is no problem with the beam, close to the Laser itself and it gets worse with the distance.

It's essentially the same problem Astronomers face when imaging stars at high magnificaton. Astronomers refer to this problem as "seeing". A thin Laser beam cut through a big amout of air is essentially like tuning a microscope on a star image.

Unfortunately the air is not a perfectly clean and perfectly stable medium. Every even so slight breeze moves air of different temperature through your beam. As you know from watching someone across a camp fire - air of diefferent temperature creates Schlieren and blurries the image. The problem is getting worse at long distances close to the ground. It is easier vertically as air gets thinner in higher regions and you cut through several layers of air instead of keeping within the "ground sheet".

There is no easy way out. You sust can statistically sample the light to find the true center. Astronomers with BIG budget can help themselves with adaptive optics that does cancel out the dynamic variations based on the theoretically expected image.

It does help quite a lot, if you enlarge the beam diameter. The "air bubbles" might be quite small. Once the beam reaches or supersedes the bubble size, it keeps its profile, but tends to wobble around like in this image of the moon.



A thin needle jumps everywhere, as it is refracted by dozens of moving "air lenses". Like on this video (the moving around is due to tracking problems)

 

lasermore

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What I see in this "videos" especially the second one ist not "flicker" of the Laser, but the result of the large air space between the source and the target. Let me guess - there is no problem with the beam, close to the Laser itself and it gets worse with the distance.

It's essentially the same problem Astronomers face when imaging stars at high magnificaton. Astronomers refer to this problem as "seeing". A thin Laser beam cut through a big amout of air is essentially like tuning a microscope on a star image.

Unfortunately the air is not a perfectly clean and perfectly stable medium. Every even so slight breeze moves air of different temperature through your beam. As you know from watching someone across a camp fire - air of diefferent temperature creates Schlieren and blurries the image. The problem is getting worse at long distances close to the ground. It is easier vertically as air gets thinner in higher regions and you cut through several layers of air instead of keeping within the "ground sheet".

There is no easy way out. You sust can statistically sample the light to find the true center. Astronomers with BIG budget can help themselves with adaptive optics that does cancel out the dynamic variations based on the theoretically expected image.

It does help quite a lot, if you enlarge the beam diameter. The "air bubbles" might be quite small. Once the beam reaches or supersedes the bubble size, it keeps its profile, but tends to wobble around like in this image of the moon.



A thin needle jumps everywhere, as it is refracted by dozens of moving "air lenses". Like on this video (the moving around is due to tracking problems)

At this juncture, I think that you and Immo1282
are correct that it is a mirage-type-effect.
 







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