Looking for the right burning laser for igniting a rocket

sydriax

Newly Enlightened
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Jun 22, 2017
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Hi all,

I run my high school's rocketry club, and we've been having a lot of trouble reliably and safely igniting our home-built solid rocket motors. They're quite small (for reasons of safety), so traditional electric igniters turn out to cause problems, so we were brainstorming about how to do it, and an idea came to my mind: laser ignition.

What I'm thinking of doing is CNC milling a very precise stand for a rocket, a disposable mirror, and a laser. The idea is that the laser would bounce up the mirror, travel through the throat of the nozzle vertically upwards until it hit the bottom of the bulkhead, onto which we would paint a small amount of red phosphorus. The phosphorous would ignite, igniting the rocket, which would then very quickly destroy the disposable mirror, which is fine by us.

As the tips of matches are coated with red phosphorus, I'd imagine that any laser that could ignite a match would do the job for us. However, we're completely inexperiened at working with high-power lasers, so my questions are as follows:

(1) Is this a worthwhile endeavor? Do you think this is reasonably practical technique, and we should pursue it, or should we just try to make our electrical igniters better?
(2) If the answer to (1) is yes, what laser would you recommend that we buy? Our initial thought suggests that it should be several hundred milliwatts and we should focus it to a point at ~10", but we're not sure what color is most appropriate for our task. The laser would also ideally be inexpensive (high school students are poor) and hackable (so that, for example, we could rig electrical controls onto it), but most importantly it should be as safe for us to use as possible. I have no intention of blinding myself at 16 -- that is my first priority.

Any thoughts are much appreciated.
 

FRITZHID

Flashlight Enthusiast
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Jun 20, 2011
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Icelandic wastelands of Monico, WI
Can it be done, of course, but there will be challenges. biggest one being overcoming distance to prevent your laser module from getting ruined my debris from the launch, which will lead to focus issues, interference and much trial and error, plus reliability will be a concern.
i'd suggest reexamining your electric matches.
 
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