Had a few questions for a senior design project

Hey yall, I'm working on a project for senior design at the moment (hopefully graduate this semester! woohoo) and had a few questions regarding lasers that I was wondering if yall could answer or at least point me in the general direction.

The basic idea of the project is a voice activated golf putting assistant that shows if your putter head is level or not, and the part I'm working on currently is the laser assembly. What our team has planned so far is to shoot a laser about 1" off the ground so it hits the putter head and reflects back (it'll probably be a modified putter head to make it more ideal). We planned on having 5 phototransistors as receivers with leds connected to them so that they would light up if the laser reflected to that particular receiver (it'll be more complex than that, but that's the general idea).

Anyways, I was reading the guide on the driver circuit for LD's and the 16x dvd burner LD... but I wasn't sure if that was a bit overkill for this project or what would be a more recommended power? The distance we're going to be working at is apprx. 10ft and will be a mix of indoor/outdoor. Safety is a big issue, especially with how this is going to be reflecting off a putter.... there shouldn't be anyone near the laser or receivers, but still I want to be as safe as possible.

Thanks for your time =)

-Aaron

Re: Had a few questions for a senior design projec

hi and welcome to the forum! that sounds like a cool idea!! even a 5mw green could work depending on how far away it is(whats a foot? ), but you can go up or down from there. the led/ reciever idea should work, although if not enough light is reflected, they won't pick it up, and they'l give a false reading. a dvd LD might work for you, although you have to put it in it's own casing, and make a driver circuit for it(which you have read)

Re: Had a few questions for a senior design projec

Would I be correct in thinking that you are going for a line scan (set parallell to the ground) from the LD?

Regards rog8811

Re: Had a few questions for a senior design projec

i think he is, otherwise he'd have to line the laser up with the whatever it's called, which would be a bit of a prob. you can get lenses that create a line without moving parts or batteries.

Re: Had a few questions for a senior design projec

Well, that was actually another idea of ours... but I wasn't sure where to find lenses for that kind of thing.

We may end up testing both ways just to get some alternative designs for the project report... The only requirement is that is has to work, but at the same time it's supposed to show that we can use what we learned in the EE program, so we're supposed to build every circuit that we can rather than use a chip or something.

To be honest, we'll probably end up going with something like the parallel beam you were referring to... I think having the laser go straight out and reflect off the putter will be too jumpy to actually get the receivers to work correctly.

Thanks for the help and the welcome =)

Re: Had a few questions for a senior design projec

i'm not quite sure where you can get the lenses, but have you seen those little 1mw red cheap lasers that come with all the caps?

Re: Had a few questions for a senior design projec

Well, this is what I have so far:

- a 5mW LD from Aixiz
- a line generating optic from Novalasers
- and like 10 CR123A batteries (mostly for if I decide to mess around with those 100mW lasers =D )

I figured that I'd build the driver circuit and do some testing with the 5mW LD first and then if it's not powerful enough I'll dig around and try to find a 10 or 50 mW laser... and the line generating optic is the backup idea, rather than have the laser reflect off the putter and go back into a phototransistor receiver, our other idea was to have the box just generate a line on the ground for about 5s and then disappear.

We figured either method would be a good way of teaching the person to hold their putter level.... but I'll keep yall updated on how the project's going as soon as my stuff comes in =)

It's probably a little late now... but are those the batteries I should be using? I have some rechargeable AA's at home and stuff... but I saw the mAH on the CR123's was pretty incredible so I figured I'd use them for the final product.

Re: Had a few questions for a senior design projec

Aerel, welcome to LPF and good luck with your project regardless of how you decide to do it, but I would like to point out a couple of things that may be of some help to you.

It will be rather difficult to get a clear enough reading from a 5mW laser spread out into a line and from that distant. I'd go with a 50mW or so simply because when spread out, the power is linearly decreased. Also, you NEED to make sure that your laser is very nicely focused so that at 10 feet the result is a tight beam as opposed to a diffuse beam.

There are very many problems with this... let me explain. In terms of having the PD rely on a reflection from the putter head, the head has to be as flat as possible... and in the case of trying to stabilize a beam across 20 feet... it needs to be almost ideal. The reflection will be very diffused and very easily affected by small vibrations. PD's are usually VERY small, and thus a reflection aimed 10 feet away from the reflection point could easily sway back and forth over the PD and would miss it entirely almost every time. I think that if you want to test for the presence of a laser reflection, you can use an enclosed photocell (solar panel) in a housing with a thin, flat, and deep opening at the front to allow the laser to come in, but limit the ambient light from filling the cell. Solar cells work well for detecting a laser, and would be much cheaper than using PD's... not to mention they are easily available all over town in many different forms and shapes and sizes. Another thing to know is that if you plan on running the laser through a rotating mirror assembly that most PD's and photocells will not pick it up as it is moving far too fast. The more of the laser's power reflected back at the photocell, the more precise yoru reading will be, and the less error your circuit will be generating. I suggest using a much tighter optic than the one used for line generating. The one you have will spread the beam so far out that at 20 feet the laser will pretty much be .1mW at best at any one spot! Try to use something that would generate a beam width about an inch at 10 feet, and then when it's reflected back it'd be 2 inches wide... which allows for a good range to be covered and not much energy loss. Also, may I suggest that you not reflect the beam off the head itself (unless you are not intending to do that) but instead use a front-surface mirror mounted vertically right above the head. That way the reflection will be ideal and easily measurable. Also, if the person decides to put (place) a ball in front of the head, or put (verb) with it, the mirror won't get damaged/bent/dirty as the head itself would.

I'm curious to see more of this project and how you get it working. For my SD project I made a laser guided computer vision system that we then later on modified to object detection because a laser was too hard to detect using affordable cameras and lasers at our disposal ;D It worked though!

GL;
DDL

P.S. Just out of curiosity, which university is this for?

Re: Had a few questions for a senior design projec

Thanks for the welcome

Yeah, I think you hit on the major problems we thought would come about from this project.... our SD project was assigned by a professor though, so we I think we may end up building it and attempting (and it sounds like failing :-/ ) to reflect it off the putter head before we can even move on to the line generation idea. The PD's are incredibly small... I think the window on them isn't much bigger than a pin head, so from 20ft out I can definitely see how that would be a problem. I hadn't thought about using solar cells... I might dig around and see if I can find some at the local electronics store.

I think that we're going to be using a modified putter head for this project... it should be pretty close to mirror-like, so we won't have to worry about dents and reflectivity. To be honest, I think we'll end up using the line generating lense as our final model... and then have the voice activation circuit just turn it on for like 5s so the golfer can get the putter perpindicular to the line. But gotta make the professor happy and try what he wanted first haha :

Thanks for the advice though, and I'll start looking around for a 50mW laser to tinker around with.

and I go to Auburn University in alabama (War Eagle!)