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Multi point laser

C

Carl Gilbert

Jan 1, 1970
0
Hi

I know next to nothing about lasers and was hoping that someone may be
able to point me in the right direction.

I need a device that can emit around 20 harmless points on a large
surface. The area is around 7 square meters and the points need to be
fairly accurate. That is, I wish to be able to change the
co-ordinates of the points on a grid basis with gaps around 5mm.
Additionally, the device should be around 8 – 10 meters away from the
surface.

I have tried to give as much spec as possible and hope that someone
may know of device or technique for performing such a task.

Many thanks, Carl Gilbert.
 
I

Ian Stirling

Jan 1, 1970
0
Carl Gilbert said:
Hi

I know next to nothing about lasers and was hoping that someone may be
able to point me in the right direction.

I need a device that can emit around 20 harmless points on a large
surface. The area is around 7 square meters and the points need to be
fairly accurate. That is, I wish to be able to change the
co-ordinates of the points on a grid basis with gaps around 5mm.
Additionally, the device should be around 8 ? 10 meters away from the
surface.

I have tried to give as much spec as possible and hope that someone
may know of device or technique for performing such a task.

20 laser pointers on individual mounts?

Do you want to be able to adjust the points to accurate coordinates,
or is waving around till they hit the right spot more the way.

Computer driven, or manual?
 
C

Carl Gilbert

Jan 1, 1970
0
I want to have them computer operated. Ideally one device that can emit
multiple points. Basically I want to display the 20 points as accuratly as
possible. No movement is necesary.

Cheers, Carl.
 
I

Ian Stirling

Jan 1, 1970
0
Carl Gilbert said:
I want to have them computer operated. Ideally one device that can emit
multiple points. Basically I want to display the 20 points as accuratly as
possible. No movement is necesary.

Fairly complex.
To clarify, do you want the 20 points to move as one, or are they all
seperate?
The cheapest way for under a few would probably be a video projector.
Might that do?
$4500 or so for the top end, but you'll be hard pressed to get
20 light pointers made for $225, under computer control.

You'll probably want to go for a non LCD based one, as they may have
bright spots you don't want.
 
S

Spajky®

Jan 1, 1970
0
I want to have them computer operated. Ideally one device that can emit
multiple points. Basically I want to display the 20 points as accuratly as
possible. No movement is necesary.

what about a laser diode + a lense+ 20x optical fibre?

-- Regards, SPAJKY ®
& visit my site @ http://www.spajky.vze.com
"Tualatin OC-ed / BX-Slot1 / inaudible setup!"
E-mail AntiSpam: remove ##
 
B

Ben Bradley

Jan 1, 1970
0
Fairly complex.
To clarify, do you want the 20 points to move as one, or are they all
seperate?
The cheapest way for under a few would probably be a video projector.

This would also come closer to the "harmless" spec than actual
lasers, such as handheld laser pointers.
 
C

Carl Gilbert

Jan 1, 1970
0
I could possibly reduce the number of lasers required. I don't like the
sound of a video projector as the device has to be low maintenance and in
location on a more permanent basis and fairly small. I would want to
control the points independently, i.e. feed co-ordinates to each one. As
few as 5 points may be acceptable but this wouldn't be ideal, 10 would be
fairly sufficient.

Cheers, Carl
 
I

Ian Stirling

Jan 1, 1970
0
Carl Gilbert said:
I could possibly reduce the number of lasers required. I don't like the
sound of a video projector as the device has to be low maintenance and in
location on a more permanent basis and fairly small. I would want to
control the points independently, i.e. feed co-ordinates to each one. As
few as 5 points may be acceptable but this wouldn't be ideal, 10 would be
fairly sufficient.

The video projector is almost certainly going to be the smallest solution.
You can get them down to under a kilo.
It may also be the cheapest.

Ok.
Details.
How far is the device from the furthest point where the lasers hit.
How accurately do you need each point to be placed?
How large a diameter can each point be, is a laser pointer OK?
Can people get between the beam projector and the target?
Can you write the code on the computer?

This is an awkward problem.
There isn't really any easier solution than a couple of motors with
position sensors on a gimbal.
This is fairly complex, and moderately expensive, especially if you
need 5 or 20.
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Carl Gilbert
I know next to nothing about lasers and was hoping that someone may be
able to point me in the right direction.

I need a device that can emit around 20 harmless points on a large
surface. The area is around 7 square meters and the points need to be
fairly accurate. That is, I wish to be able to change the co-ordinates
of the points on a grid basis with gaps around 5mm. Additionally, the
device should be around 8 – 10 meters away from the surface.

I have tried to give as much spec as possible and hope that someone may
know of device or technique for performing such a task.

You could make something, using a single laser and some optics to split
the beam into 20 and using mirrors deflected by solenoids to steer the
beams to the places you want. Optical components to do at least some of
these things are commercially available. I don't know whether there is a
newsgroup for optical technology, but it might be worth looking for one.
 
C

Carl Gilbert

Jan 1, 1970
0
Ok.
Details.
How far is the device from the furthest point where the lasers hit.
How accurately do you need each point to be placed?
How large a diameter can each point be, is a laser pointer OK?
Can people get between the beam projector and the target?
Can you write the code on the computer?


On a very rough basis the device will be about 10 foot from the surface.
Assuming a surface of 10 x 10 foot, the furthest dictance from the surface
should be (without calculations) 13 foot.

The accuracy of each point has to be within 10mm of the co-ordinates and the
diameter of the point should be between 1mm and 10mm approx as long as it is
visable.

* A human hand WILL come between the device and the surface.

I can write code, I have currently develop with VB.NET but may be willing to
learn another language for this project should it not be too complex and
demanding.

After further thought, I could use just the ONE beam/point. My intention is
to display a beam unitl something can be placed at that point. Once
located, the operator could then trigger the system to display the next
point and work through the points rather than displaying them all at once.

The laser would need to therefore change co-ordinates fairly quickly, up to
5 seconds would suffice between the previous point being validated and the
next point being placed.

Many thanks, Carl Gilbert
 
W

Winfield Hill

Jan 1, 1970
0
Carl Gilbert wrote...
After further thought, I could use just the ONE beam/point. My intention
is to display a beam unitl something can be placed at that point. Once
located, the operator could then trigger the system to display the next
point and work through the points rather than displaying them all at once.

The laser would need to therefore change co-ordinates fairly quickly, up
to 5 seconds would suffice between the previous point being validated and
the next point being placed.

There are elegant 2-axis mirror galvos and servos that can do the job.
They're fast (1 to 5ms), but expensive. www.cambridgetechnology.com

A slow setup using stepping motors may be sufficient for you, and
more compatible with the technology (computer programming) you're
comfortable with.

Thanks,
- Win

whill_at_picovolt-dot-com
 
I

Ian Stirling

Jan 1, 1970
0
Carl Gilbert said:
On a very rough basis the device will be about 10 foot from the surface.
Assuming a surface of 10 x 10 foot, the furthest dictance from the surface
should be (without calculations) 13 foot.

The accuracy of each point has to be within 10mm of the co-ordinates and the
diameter of the point should be between 1mm and 10mm approx as long as it is
visable.

That's an accuracy of around +- 10mm/3m = +-3 milliradians, or around
+-.2 degrees.
* A human hand WILL come between the device and the surface.

The limits are generally more related to if it can shine
into the eye.

(does anyone reading this happen to know if there are limits for what
you can expose hands to?)

While I could speculate on the design, it doesn't sound like you
actually want to build. (a couple of fine 400 steps/rev stepper motors,
a microstepping drive, and a couple of mirrors mounted on the stepper
motors may do fine, along with an interruptor to sense position.

Thinking about it, I should probably have referred you to sci.optics,
where they probably know where to buy these off the shelf.

If you can do with one point, then that will likely be lots cheaper.

There are devices which have voice coils instead of stepper motors, and
are much, much faster.
 
C

Carl Gilbert

Jan 1, 1970
0
Cheers for all the help, I seem to now be making some progress.

It sounds like a few stepper motors will do the job. I should imagine voice
coils would be too elaborate for this project and introduce unnecessary
costs.

As I am very unfamiliar with this field, I was slightly confused as to why
an interruptor would be required and what this actually does.

As for the build, I am very keen to build a prototype, so finding out more
information on specific products most suited to this task is key at the
moment.

I think the advice you have given me is based on a good understanding of
what I want to achieve. Essentially, I now want to build a unit that I can
connect to a PC and feed co-ordinates, moving from one point to the next is
of no importance as the SW package I develop later will cope with this.

Any further help on this would be greatly apreciated or if you feel
sci.optics would be of more help then I shall refer to that group.

Regards, Carl Gilbert.


The limits are generally more related to if it can shine
into the eye.

(does anyone reading this happen to know if there are limits for what
you can expose hands to?)

There is very little risk of this, hand exposure only.
 
I

Ian Stirling

Jan 1, 1970
0
Carl Gilbert said:
Cheers for all the help, I seem to now be making some progress.

It sounds like a few stepper motors will do the job. I should imagine voice
coils would be too elaborate for this project and introduce unnecessary
costs.

As I am very unfamiliar with this field, I was slightly confused as to why
an interruptor would be required and what this actually does.

It's just an optical sensor to sense when the device is in
position.
On switchon, you run the mirrors round until you get a signal.
This tells you where "zero" is, so you can point accurately.
As for the build, I am very keen to build a prototype, so finding out more
information on specific products most suited to this task is key at the
moment.

Depends how far you want to go.
I believe there are stepper motor control boards available that plug into
PCs.
On the other hand, you might do it with a couple of modified sound-cards
(to provide the D/A) a few power op-amps, and sundry stuff.

What sort of stuff have you designed before, hardware-wise?
I think the advice you have given me is based on a good understanding of
what I want to achieve. Essentially, I now want to build a unit that I can
connect to a PC and feed co-ordinates, moving from one point to the next is
of no importance as the SW package I develop later will cope with this.

Any further help on this would be greatly apreciated or if you feel
sci.optics would be of more help then I shall refer to that group.

It depends if you want to build, or buy.
The people over in sci.optics will probably know where to buy the
stepper/mirror assembly off the shelf, saving you having to fabricate it.
 
G

Guy Macon

Jan 1, 1970
0
Carl Gilbert said:
I can write code, I have currently develop with VB.NET but may be willing to
learn another language for this project should it not be too complex and
demanding.

VB.NET can certainly do the job, but there may be speed issues
if you try some approuaches such as steering mirrors. There
is a language that is a lot like VB.NET butbwith reduced
"pretty things on the screen" capabilities, increased "control
the hardware" capabilities and which is MUCH faster; PowerBASIC.
Go to http://www.powerbasic.com and look at PB/CC.
 
C

Carl Gilbert

Jan 1, 1970
0
What sort of stuff have you designed before, hardware-wise?


Here you have highlighted my biggest downfall regarding this project. The
coding side of things should be no problem, as for the hardware, I have
little experience with this.

As for the development of the laser pointer, I would opt to buy all the
necessary components. Basically I want to buy a few components, put them
together, connect them to my PC and be able to feed them co-ordinates. From
here I would then be able to easily progress with the software side of
things.

Regards, Carl Gilbert
 
C

Carl Gilbert

Jan 1, 1970
0
What sort of stuff have you designed before, hardware-wise?


Here you have highlighted my biggest downfall regarding this project. The
coding side of things should be no problem, as for the hardware, I have
little experience with this.

As for the development of the laser pointer, I would opt to buy all the
necessary components. Basically I want to buy a few components, put them
together, connect them to my PC and be able to feed them co-ordinates. From
here I would then be able to easily progress with the software side of
things.

Regards, Carl Gilbert
 
I

Ian Stirling

Jan 1, 1970
0
Carl Gilbert said:
Here you have highlighted my biggest downfall regarding this project. The
coding side of things should be no problem, as for the hardware, I have
little experience with this.

As for the development of the laser pointer, I would opt to buy all the
necessary components. Basically I want to buy a few components, put them
together, connect them to my PC and be able to feed them co-ordinates. From
here I would then be able to easily progress with the software side of
things.

Ok...
My first step would be to ask over in sci.optics, if anyone has any ready
solutions. Maybe sci.astro.amateur, where they may have usefull input
from telescope pointers.
The problem is that though there are bits that would go together with little
effort, finding them may not be so easy if you don't know how.
 
C

Carl Gilbert

Jan 1, 1970
0
Ok, thank you for your help. I shall pursue such components in sci.optics.

Carl
 
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