Hacking a laser tape measure

[N_Cook]

A neat cheap little 50m range (checked true) measurer, would it be
possible to change the f crystal to hopefully f/3 or so and get 150m range.
Assuming (looks possible) to split send and receive and enlarge the 15mm
capture window to 150mm window.
Also assuming I can identify which is the crystal and is not integral
with the ASIC, not epoxied over anyway. Would the LCD likely become
unreadable at 1/3 the original drive f. Accuracy would be worse but
decimeter resolution over 150m would be fine

 

[pfjw@aol.com]

MY concern would be whether or not the optics would support the longer distance. After all the trouble, you might have just a piece of landfill.

A Bosch device capable of that 150 feet is about US$60 these days, or less. And a cheaper off-brand device may be had for less than US$30.

Peter Wieck
Melrose Park, PA

 

[N_Cook]

On 06/03/2019 12:05, pfjw@aol.com wrote:

MY concern would be whether or not the optics would support the longer distance. After all the trouble, you might have just a piece of landfill.

A Bosch device capable of that 150 feet is about US$60 these days, or less. And a cheaper off-brand device may be had for less than US$30.

Peter Wieck
Melrose Park, PA

Its optics I'm playing around at the moment with this 17GBP 50m (150ft)
not poking around inside yet.
Just in the process of boring/grinding a hole through a 150mm glass 3
dioptre magnifying glass to try passing the the transmit beam thru the
centre and then larger capture area for the focussed received, to see
how that works at 50m initially, ie how much darker a "reflector" would
be the new minimum .

 

[N_Cook]

On 06/03/2019 12:33, N_Cook wrote:

On 06/03/2019 12:05, pfjw@aol.com wrote:
MY concern would be whether or not the optics would support the longer
distance. After all the trouble, you might have just a piece of landfill.

A Bosch device capable of that 150 feet is about US$60 these days, or
less. And a cheaper off-brand device may be had for less than US$30.

Peter Wieck
Melrose Park, PA


Its optics I'm playing around at the moment with this 17GBP 50m (150ft)
not poking around inside yet.
Just in the process of boring/grinding a hole through a 150mm glass 3
dioptre magnifying glass to try passing the the transmit beam thru the
centre and then larger capture area for the focussed received, to see
how that works at 50m initially, ie how much darker a "reflector" would
be the new minimum .

So far , so good. 5mm hole ground in the centre and simply holding unit
in line with the hole, can produce a 5m reading without forcing errors
from its operational window , across the room.
Now to mount in a rigid tube , to try outdoors, over 50m span.

 

[Sjouke Burry]

On 6-3-2019 10:02, N_Cook wrote:

A neat cheap little 50m range (checked true) measurer, would it be
possible to change the f crystal to hopefully f/3 or so and get 150m range.
Assuming (looks possible) to split send and receive and enlarge the 15mm
capture window to 150mm window.
Also assuming I can identify which is the crystal and is not integral
with the ASIC, not epoxied over anyway. Would the LCD likely become
unreadable at 1/3 the original drive f. Accuracy would be worse but
decimeter resolution over 150m would be fine

return power on the detector will be 81 times less than it is right now,
(twice the square law), so I think you are out of luck.

 

On Wednesday, 6 March 2019 17:24:57 UTC, Sjouke Burry wrote:

On 6-3-2019 10:02, N_Cook wrote:

A neat cheap little 50m range (checked true) measurer, would it be
possible to change the f crystal to hopefully f/3 or so and get 150m range.
Assuming (looks possible) to split send and receive and enlarge the 15mm
capture window to 150mm window.
Also assuming I can identify which is the crystal and is not integral
with the ASIC, not epoxied over anyway. Would the LCD likely become
unreadable at 1/3 the original drive f. Accuracy would be worse but
decimeter resolution over 150m would be fine

return power on the detector will be 81 times less than it is right now,
(twice the square law), so I think you are out of luck.

hence the larger window, 100x the area.


NT

 

[whit3rd]

On Wednesday, March 6, 2019 at 9:24:57 AM UTC-8, Sjouke Burry wrote:

On 6-3-2019 10:02, N_Cook wrote:
A neat cheap little 50m range (checked true) measurer... enlarge the 15mm
capture window to 150mm window....Accuracy would be worse but
decimeter resolution over 150m would be fine

return power on the detector will be 81 times less than it is right now,
(twice the square law), so I think you are out of luck.

You might consider using a retroreflective surface as your target (there's
corner-cubes, bike reflectors, or Scotchlite products available).

 

[Mike Coon]

In article <a82e7e13-2aa9-4597-bfb9-d9397120c505@googlegroups.com>,
whit3rd@gmail.com says...

On Wednesday, March 6, 2019 at 9:24:57 AM UTC-8, Sjouke Burry wrote:
On 6-3-2019 10:02, N_Cook wrote:
A neat cheap little 50m range (checked true) measurer... enlarge the 15mm
capture window to 150mm window....Accuracy would be worse but
decimeter resolution over 150m would be fine

return power on the detector will be 81 times less than it is right now,
(twice the square law), so I think you are out of luck.

You might consider using a retroreflective surface as your target (there's
corner-cubes, bike reflectors, or Scotchlite products available).

Perhaps that depends on whether the target being ranged is barely
intended to be aware of the red dot on forehead! (I have not been
reading all this thread...)

BTW Does the bigger window have a lens to concentrate the flux onto the
same sensor?

Mike.

 

[pfjw@aol.com]

On Thursday, March 7, 2019 at 3:29:10 AM UTC-5, Mike Coon wrote:

BTW Does the bigger window have a lens to concentrate the flux onto the
same sensor?

Whatever the intent - this is a perfect example of running down the proverbial rabbit-hole. Even if entirely possible, the results are dubious and the utility of the equipment destroyed except as a curiosity.

Peter Wieck
Melrose Park, PA

 

On Thu, 7 Mar 2019 06:26:35 -0800 (PST), "pfjw@aol.com"
<peterwieck33@gmail.com> wrote:

On Thursday, March 7, 2019 at 3:29:10 AM UTC-5, Mike Coon wrote:

BTW Does the bigger window have a lens to concentrate the flux onto the
same sensor?

Whatever the intent - this is a perfect example of running down the proverbial rabbit-hole. Even if entirely possible, the results are dubious and the utility of the equipment destroyed except as a curiosity.

Peter Wieck
Melrose Park, PA

We don't know yet if the laser measure will work. Whether its utility
is destroyed or not. In fact, it seems to be working so far. I'm glad
he is posting his experiments.
Eric

 

[N_Cook]

On 06/03/2019 21:22, whit3rd wrote:

On Wednesday, March 6, 2019 at 9:24:57 AM UTC-8, Sjouke Burry wrote:
On 6-3-2019 10:02, N_Cook wrote:
A neat cheap little 50m range (checked true) measurer... enlarge the 15mm
capture window to 150mm window....Accuracy would be worse but
decimeter resolution over 150m would be fine

return power on the detector will be 81 times less than it is right now,
(twice the square law), so I think you are out of luck.

You might consider using a retroreflective surface as your target (there's
corner-cubes, bike reflectors, or Scotchlite products available).

That reminded me one of these was laying neglected in the store, broken
power supply ISTR.

http://www.aga-museum.nl/page/geodimeter-model-12-

the 14 version.
I dug it out and opened it up before trying to power up.
1978/79 CMOS and TTL and a rat's nest of after-thought/fudge flying
components, despite OEM. Mini Nixi tubes I think rather than the pre-7
segment LED, electroluminescent displays , or perhaps mini CC display,
difficult to view.
Looking at the manual the original spec was up to 60km range with
exceptionaly clear visibility it says ,and requiring one of those
multi-prism reflectors , they left on the moon.
I'd still rather mod a new replaceable DIY unit than this EDM that
should be in a museum.

 

[pfjw@aol.com]

On Thursday, March 7, 2019 at 12:17:36 PM UTC-5, et...@whidbey.com wrote:

We don't know yet if the laser measure will work. Whether its utility
is destroyed or not. In fact, it seems to be working so far. I'm glad
he is posting his experiments.

Eric:

I am writing from the perspective of one who must rely on accurate measurements for revenue, and whose instruments are calibrated to this end.

For the purposes of a hobby - that is an entirely different matter.

Peter Wieck
Melrose Park, PA