532 Collimated IR output

[grainde]

Just thought Id make a quick post about IR from 532 pens and lasers.

Most people seem to say that yes the IR is dangerous, but its not really too much of an issue as it is not collimated. Well I decided to take some pics to find out whether the IR was indeed collimated and focused with the 532.

In my recent review on a 301 laser I mentioned the IR component, which was basically all 1064 nm light. I also did a mini review for Kommed some time back for one of his ebay pens. Below are the graphs of the two lasers each with an IR filter:

532 ebay pen - Output 44 mW so 21 mW IR

301 laser - Output 91 mW so 19 mW IR

For the pictures I used my old canon 20D with a 10-22 EFS lens and a 77 mm B+W IR 093 filter. This filter blocks 100% of all visible light, but allows approx 15 % transmission at 810 nm and over 90 % above 1000 nm. Distance from camera to wall 1.5 m.

The first pic is actually composed of 3 different 532 lasers, but one (the control laser - Global Laser Firefly) is IR filtered, so you cant see it! (Order - Firefly : Kommed pen : 301 laser). Note: The firefly control laser confirms that 532 is completely blocked by the filter, this means the dots are purely IR.

The second and third photos are without and with the filter again on the 301 laser.

Finally I used photoshop to superimpose the photos and reduced the opacity of the 532 picture to show the IR dot beneath.

Zoomed in...

Conclusion: Yes the IR is extremely well collimated!! Please take care... :beer:

 

[TheDukeAnumber1]

I actually had wondered that for a while. GJ

 

[hwang21]

Nice job, thanks for the info :beer:

 

[Spooky]

+1, great info, many thanks

cheers

Dave

 

[NO4H99]

Thanks so much, I've actually been searching for this info for months. +REP coming up

An IR dot with twice the diameter of the visible beam (which this one looks near to) has a NOHD four times smaller though, right? If so, it should be fairly safe at a distance of several yards.

Did both lasers have roughly the same infra-red divergence?

Thanks.

 

[grainde]

Thanks so much, I've actually been searching for this info for months. +REP coming up

An IR dot with twice the diameter of the visible beam (which this one looks near to) has a NOHD four times smaller though, right? If so, it should be fairly safe at a distance of several yards.

Did both lasers have roughly the same infra-red divergence?

Thanks.

Compare the size of the IR dot to pic 2. Its actually much smaller than the visible dot. The fuzzy light purple region around the white dot in the IR pic is scatter and interference. The scatter and interference region from the green is much larger - The sensitivity of the camera sensor to IR light will play a role here though as it is IR filtered, so the exposure for the IR pictures had to be increased to around 2 mins. In the last comparison IR photo and the one that was superimposed it was actually 5 mins! Please note the picture 2 will not show any IR, as the exposure was too short at 1/80.

From the pics it looks like the IR is actually more collimated and has a better divergence than the green, so the NOHD will be greater for the IR component.

Yes both lasers had a similar IR divergence, although the collimation and hence dot of the 301 laser was slightly better (? ). That can be seen in the first pic. :beer:

 

[Cyparagon]

From the pics it looks like the IR is actually more collimated and has a better divergence than the green

Are we looking at the same pictures?

 

[NO4H99]

To me, It looks like the green is collimated slightly better (the bright dot in the middle of the IR spot in the last pic). The green around it is just the diffuse reflection picked up by the camera, right?

 

[grainde]

To me, It looks like the green is collimated slightly better (the bright dot in the middle of the IR spot in the last pic). The green around it is just the diffuse reflection picked up by the camera, right?

No, I used photo shop to reduce the opacity of the green layer to around 30%. The bright white dot in the center is IR. You can see that in the other IR pics too. The actual bright white/green dot from the green was larger and would have obscured the IR and the IR scattering from the last pic, if I hadnt reduced its intensity by blending. :beer:

Edit: Can't see the problem? Compare pics 2 and 3 directly. There is a very bright white dot from the IR in the center of pic 3. There is a very bright white/green dot in the center of pic 2. The intensity of the green dot was reduced drastically in pic 4 to leave only the bright IR dot when they were superimposed. The center of the IR dot is around half that of the green dot. Pics 2 and 3 were exactly the same size, resolution and position so a direct comparison of dot sizes is possible. The IR is very well collimated and more so than the green. Ive just quickly zoomed in on the IR dot below (not to scale ie more than 100% crop so you cant compare by measuring the size with a ruler....) The scattering and interference area around the dot is much smaller than with the green and the multiple colours in the pic are due to high ISO noise...

Edit2: Ok I think I know what you are saying. You are including the scatter area around the bright white dot as the IR dot. The IR dot is the white region and the outer redish area is the scattering and interference. The size of the white dot (collimated area) + scattering is the same size as the white dot (collimated area) from the green. The green scattering and interference ie green area around the white/green dot from the green is far larger. The white dot in the center of the IR region has nothing to do with visible light as that has been completely filtered.

Edit3: Ok just spent half an hour cropping the images exactly to zoom in on the dots and enable a direct comparison.

:beer:

 

[NO4H99]

OK, I see what you're saying. Thanks for spending the extra time to set me straight

 

[Cyparagon]

And how much of that is blooming? You said so yourself the filter you used blocks 90% of 810nm. The green will saturate the sensor and spill over into adjacent pixels. Cameras are not terribly accurate representations of lasers. We all know that.

 

[grainde]

And how much of that is blooming? You said so yourself the filter you used blocks 90% of 810nm. The green will saturate the sensor and spill over into adjacent pixels. Cameras are not terribly accurate representations of lasers. We all know that.

The IR exposure was over 5 mins so the sensor around the dot was also saturated in the IR pic. The filter actually blocks 80 - 85% at 810. The comparison is accurate enough and the point of the exercise, in case you forgot, was to show that the IR is collimated - This has been proven.

 

[BurningLaserGuy]

If the laser have no IR colimation lens, that laser is a counterfeit one, and I really want to avoid them. 21mW of IR from a green laser is nasty for me. Thanks for the info, +1 from me.
EDIT 1:If I'm wrong please tell me.

 

[grainde]

21 mW is quite normal for the cheaper unfiltered 532's. My 5 mW ebay pen measured 44 mW, but half of that was IR!

The lens will collimate both the 532 and IR, but the focal plane of the IR will be slightly different. :beer:

 

[hwang21]

So, once again, WL is wrong, or at least misleading: Why is IR Bad?

 

[KapHn8d]

Cool. I won't embed the image since it's from a different thread, but I recently did a test with another DPSS laser that shipped accidentally with a faulty IR filter (and is being corrected by the manufacturer because they are awesome)... it's a 473 and not a 532, but the IR was certainly collimated to some extent. I took two images that were IR only... one with a Hoya photographic filter that completely blocks (100%) all light less than 720nm and another with a IR converted DSLR and you can clearly see the IR beam is there... check it out.

Cheers!