[EE] light sensor array?

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[EE] light sensor array?

Neil
I want to measure the position (height) of a laser line level (device
that projects a horizontal line of light).  2" of measurement would be
nice, 1" I'd say is minimum.

First thought is that I could use a light sensor array (such as in a
sheet scanner), but this is a one-off project, and I'm not up for
finding one that I can hack and then trying to reverse engineer it right
now.
The ones I'm finding on Digikey etc (which will have datasheets) are
low-cost enough ($10-$20), but either have a very short range (~0.5" or
less), or the longer ones are discontinued.
Any recommendations for one of these?  I don't need high resolution
(even 1mm is fine).

Yes, I could put the sensor on a linear servo, but then I'd have to
ensure that mechanism is tight and not introduce any noticeable errors
in the system.

Alternate option is to let the light hit a diffuser (like say parchment
paper) and use a camera on the other side to detect the height of the
light line.  I'd have to (finally) learn openCV perhaps, but that's prob
fine.

Still thinking of other ways to do this too, even perhaps a curved lens
or mirror to compress a couple inches of range down to fit one of the
available sensors.

Brainstormy thoughts appreciated.

Cheers,
-Neil.


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Re: [EE] light sensor array?

Bob Blick-5
That one is sort of down my alley. Commercial laser detectors for the construction industry are of two varieties - ones that work with rotating lasers and ones that work with modulated lasers. Either of those make detecting the laser a whole lot easier. Ambient light is another obstacle, both sunlight and AC powered LED indoor illumination.

If you describe the parameters a little more I might be able to give you some tips.

Friendly regards, Bob

________________________________________
From: [hidden email] <[hidden email]> on behalf of Neil
Sent: Friday, September 18, 2020 12:11 PM
To: Microcontroller discussion list - Public.
Subject: [EE] light sensor array?

I want to measure the position (height) of a laser line level (device
that projects a horizontal line of light).  2" of measurement would be
nice, 1" I'd say is minimum.

First thought is that I could use a light sensor array (such as in a
sheet scanner), but this is a one-off project, and I'm not up for
finding one that I can hack and then trying to reverse engineer it right
now.
The ones I'm finding on Digikey etc (which will have datasheets) are
low-cost enough ($10-$20), but either have a very short range (~0.5" or
less), or the longer ones are discontinued.
Any recommendations for one of these?  I don't need high resolution
(even 1mm is fine).

Yes, I could put the sensor on a linear servo, but then I'd have to
ensure that mechanism is tight and not introduce any noticeable errors
in the system.

Alternate option is to let the light hit a diffuser (like say parchment
paper) and use a camera on the other side to detect the height of the
light line.  I'd have to (finally) learn openCV perhaps, but that's prob
fine.

Still thinking of other ways to do this too, even perhaps a curved lens
or mirror to compress a couple inches of range down to fit one of the
available sensors.

Brainstormy thoughts appreciated.

Cheers,
-Neil.



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Re: [EE] light sensor array?

Denny Esterline-2
In reply to this post by Neil
That's a pretty wide open description, but one thought that occurs is
construction surveying laser receivers. A couple different categories, some
handheld with a display of some sort, the other type gets mounted to
earthmoving equipment (bulldozers, etc) and has an output that is used to
control the grade height.

No experience with this company, but their web site shows several options
of both types and has listed pricing:
https://www.engineersupply.com/construction-lasers.aspx
Look for "Laser Detectors" and "Machine Control Laser Detectors"

Food for thought at least.
-Denny



On Fri, Sep 18, 2020 at 12:15 PM Neil <[hidden email]> wrote:

> I want to measure the position (height) of a laser line level (device
> that projects a horizontal line of light).  2" of measurement would be
> nice, 1" I'd say is minimum.
>
> First thought is that I could use a light sensor array (such as in a
> sheet scanner), but this is a one-off project, and I'm not up for
> finding one that I can hack and then trying to reverse engineer it right
> now.
> The ones I'm finding on Digikey etc (which will have datasheets) are
> low-cost enough ($10-$20), but either have a very short range (~0.5" or
> less), or the longer ones are discontinued.
> Any recommendations for one of these?  I don't need high resolution
> (even 1mm is fine).
>
> Yes, I could put the sensor on a linear servo, but then I'd have to
> ensure that mechanism is tight and not introduce any noticeable errors
> in the system.
>
> Alternate option is to let the light hit a diffuser (like say parchment
> paper) and use a camera on the other side to detect the height of the
> light line.  I'd have to (finally) learn openCV perhaps, but that's prob
> fine.
>
> Still thinking of other ways to do this too, even perhaps a curved lens
> or mirror to compress a couple inches of range down to fit one of the
> available sensors.
>
> Brainstormy thoughts appreciated.
>
> Cheers,
> -Neil.
>
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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Re: [EE] light sensor array?

Nicola Perotto
In reply to this post by Neil
Hi Neil & all,
some years ago (circa 2006) a friend and I updated an old equipment that used a
special paper to print on.
We removed all paper related mechanism and used a lens with a Hamamatsu S9226
CCD (a line of 1024 pixel) controlled by a PIC 16F767. The output was sent to a
PC with a serial to USB adapter (5 devices for 1 PC).

http://nicolaperotto.it/qdrupal/sites/default/files/images/particolare-interno.jpg

I don't remember a lot of details but I'm sure that it was not a difficult project.
Cheers,
        Nicola


On 18/09/2020 21:11, Neil wrote:

> I want to measure the position (height) of a laser line level (device
> that projects a horizontal line of light).  2" of measurement would be
> nice, 1" I'd say is minimum.
>
> First thought is that I could use a light sensor array (such as in a
> sheet scanner), but this is a one-off project, and I'm not up for
> finding one that I can hack and then trying to reverse engineer it right
> now.
> The ones I'm finding on Digikey etc (which will have datasheets) are
> low-cost enough ($10-$20), but either have a very short range (~0.5" or
> less), or the longer ones are discontinued.
> Any recommendations for one of these?  I don't need high resolution
> (even 1mm is fine).
>
> Yes, I could put the sensor on a linear servo, but then I'd have to
> ensure that mechanism is tight and not introduce any noticeable errors
> in the system.
>
> Alternate option is to let the light hit a diffuser (like say parchment
> paper) and use a camera on the other side to detect the height of the
> light line.  I'd have to (finally) learn openCV perhaps, but that's prob
> fine.
>
> Still thinking of other ways to do this too, even perhaps a curved lens
> or mirror to compress a couple inches of range down to fit one of the
> available sensors.
>
> Brainstormy thoughts appreciated.
>
> Cheers,
> -Neil.
>
>

--

Nicola Perotto - NP Engineering
Sistemi Informatici ed Elettronici
skype: nicolap
mob IT: +39 335 7162 582
mob HU: +36 30 417 3780
tel: +39 06 916 502 732
fax: +39 0439 633 1191

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