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[DPRG] FW: Any ideas?

Subject: [DPRG] FW: Any ideas?
From: gfe gfe at coollink.net
Date: Tue Oct 10 20:55:33 CDT 2000

I bought a $6.00 laser pointer from Office Depot with the idea of using it
in a DTMF system, But as WC pointed out no luck getting it to modulate. But,
I'm thinking it might make an appearance in Roborama 2001a.

Frank Elia

----- Original Message -----
>From: "RoboVac" <robovac at mninter.net>
To: "Robert L. Jordan" <rljordan at airmail.net>; "Dprglist at Dprg. Org (E-mail)"
<dprglist at dprg.org>
Cc: <fhb2000 at pacbell.net>
Sent: Tuesday, October 10, 2000 9:35 PM
Subject: Re: [DPRG] FW: Any ideas?


>
> The standard method for increasing the range of photoelectric sensors for
> this sort of application is to pulse the beam.  To do this first measure
the
> amount of returned light with the light turned off.  Then measure the
amount
> of returned light with the light turned on.
>
> Subtracting the two values removes the effects of room lights, sun shine,
> etc.  Because of the removal of the noise from any external lights the
> signal to noise ratio is higher and the sensor works at longer distances.
>
> The same technique can be used for a laser sensor also.  However not all
> laser can be pulsed in this manner.  Most of the lasers used in laser
> pointers need to be left on for longer then the standard 40kHz or they do
> not emit any light.
>
> William Crolley
>
> ----- Original Message -----
> From: Robert L. Jordan <rljordan at airmail.net>
> To: Dprglist at Dprg. Org (E-mail) <dprglist at dprg.org>
> Cc: <fhb2000 at pacbell.net>
> Sent: Sunday, October 08, 2000 10:08 PM
> Subject: [DPRG] FW: Any ideas?
>
>
> > Here is a good question I received. Any ideas for Hank? Sounds like he
is
> asking how to get more detection distance from a laser and detector at 810
> nm. My thought is to use a lens in front of the detector to focus at a
> distance.
> > Any other suggestions or ides? Just copy the list and Hank.
> >
> > Thanks
> > Robert L. Jordan
> >
> > -----Original Message-----
> > From: Hank [SMTP:fhb2000 at pacbell.net]
> > Sent: Sunday, October 08, 2000 3:22 PM
> > To: rljordan at airmail.net
> > Subject: Any ideas?
> >
> > Do you or someone you know have any optoelectronics ideas?  It's a a
> silicon detector problem.  I'm utilizing the BS2SX and a 5mw laser diode
> module @ 810nm and a silicon detector with a 810nm narrow bandwidth filter
> to measure when this IR laser pointer strikes black or white.  Laser and
> detector are side by side and measure light reflected back.  I know it's
> possible or those long range bar code scanners wouldn't work.  Only need
> object detection not bar codes.
> > I can only detect out 2-3ft, but need 8ft range.  I don't understand the
> > capacitance or resistance to make detector more sensitive.
> > I think my op amp is maxing out too.
> > Thanks - hope you can help,
> > Hank Burbeck
> >
> >
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> >
>
>
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