Forensic Bullet Path Trajectory Laser Tool - Design Challenge

[madmacmo]

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Last edited by madmacmo; 07-11-2013 at 05:11 PM.

http://laserpointerforums.com/f42/f...ectory-laser-tool-design-challenge-83800.html
http://web.archive.org/web/20130821...ectory-laser-tool-design-challenge-83800.html
Forensic Bullet Path Trajectory Laser Tool - Design Challenge
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One of my neighbors is the chief CSI officer for our city’s police department and he was super impressed with my laser pointers that I demoed during the block party our neighborhood had for 4th of July this last week.

He was in awe at how well the green DPSS and blue 445 beams were visible as compared to the red 5mW rated ones he uses for bullet path trajectory forensics and that it is a pain to always have to use an aerosol spray can or Halloween like fogger machine in order to sufficiently view the beam path.

In specific I believe he would be most interested in having a moderately powerful blue or green laser designed similar to the following "Forensic Bullet Trajectory Laser Assembly" Laser Trajectory Alignment Chuck





Note: the presently readily available multimode blue 445s would not provide optimal solutions because of the “bar” shape dot they emit, nor will the 532nm green modules work very well due to the random off center beam exit angle associated with the DPSS crystal optics positioning during manufacture (i.e. the DPSS green modules would be difficult to near impossible to align on the end of a forensics trajectory rod)

I surmise this application would require either a single mode blue or a direct green diode and I must admit that I am not currently aware of the present availability, the associated cost or of the rated power of the present generation of these diodes. I will also have to inquire from him for what expected run times would be needed; however I see no reason this application could not have an external power supply with just the laser assembly/driver/optics designed to be mounted on end of the trajectory positioning rod.

I told him that I would check around here on LPF as I knew if anyone could professionally fashion a build with which he could experiment it would be most likely be one of you guys. He also said he felt like there could be a significant demand among the other CSI officers within other cities with whom he collaborates given that it is a common complaint among them about how weak the commercially available red forensic lasers are.

He of course would have to be educated about the hazards of higher power laser pointers where he would have to mitigate the risks with safety procedures, personal protective equipment (safety goggles), and maintaining control of the beam path (much the same as they do with their service weapons).

Let me know your thoughts.

Edit: I realize that the single mode blues and especially the direct greens that have been recently available are rated at significantly lower power outputs than the 445 multimodes and 532 DPSSs; however just the fact that our eyes are much more sensitive to these wave lengths in apparent brightness should in and of itself be of significant forensic benefit in my friend's line of work.
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[Sigurthr]

Another problem with using a high power 445 would be destruction of evidence at the target due to heat.

Single mode 450s should do fine, at around 100mW you can follow the beam well in dim light as long as the air isn't ultra clean.

You should show him a 12x diode ~700mW defocussed for fluorescence work. Doesn't stand up to 365nm LED, but I know out local CSI here couldn't afford LED tech and are still using the baby 4W fluoro black light bulbs and the cheap 410nm multi LEDs with tons of white leakage.

 

[ApexProxy]

IMO, this would be quite easy to make. I would run a PL520 at 200-250mA in a custom made X-Boost and 18650 powered pointer. If you want I could probably make you one pretty easily.

 

[mhemling33]

Really cool idea. I would definitely use a green laser for this. I might be wrong but i believe green is 4 times brighter to us then blue.

here is stuff I recently made for mounting on my guns that I use to shoot but you could mount it on a dummy gun for simulation purposes. By made I mean these are gun sights I have gutted and put my stuff in.

these are both around 100mw greens






The 2w blues look cool but there are very dangerous too

 

[BShanahan14rulz]

These rods are placed in bullet holes, estimating to a decent degree where the bullet came from. The idea is that for example the picture linked above, having ~100 lasers might be more expensive than using already purchased trajectory impact markers with a "laser adapter"

Seems like it might be a bit hard to accomplish without access to professional tools and techniques. You want the device to be somewhat light weight, but still need xy adjustment for accuracy and the ability to mount onto the ends of various diameter rods.

Maybe if you could find a cheap host that already has output XY adjustments and swap out the diode and electronics? The chuck looks like it was cannibalized from an old hand drill

 

[ApexProxy]

A complete laser should not require an XY adjustment though. The point would be for the beam to be perfectly straight from the alignment rod so as long as the laser is aligned from the beginning and cannot shift out of alignment there would be no need. I'm pretty confident that I could come up with something that would completely annihilate the weak units they currently use lol. I think running an 18650 would allow for some really really long runtimes and PL520s run cool, especially at a conservative 200-250mA.