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Topic: Open source, TOF laser rangefinder (Read 36621 times) previous topic - next topic

ig-x


Laser_Developer

Congratulations ig-x! A superb analysis of a complex signal processing problem. You are now one of those rare people who have understood and appreciated how difficult it is to analyze events happening at the speed of light. Imagine trying to do all this with real-time data!

davidf2281

#32
Oct 12, 2014, 07:56 pm Last Edit: Oct 13, 2014, 04:26 am by davidf2281 Reason: 1
@Laser_Developer,

Just to say thanks for taking the time to post this excellent information. I'd been pondering for a few days on how to achieve laser TOF without crazy-high-bandwidth electronics, and the SETS technique hadn't occurred to me.

One question, if you have a few seconds. I understand your control logic is responsible for generating a continuous SETS sampling control signal with gradually incrementing, precisely controlled delta-T over the course of many samples, to produce the expanded timebase. But I'm having difficulty parsing how the precise delta-T delay is actually generated: is it a 'beating' signal generated by phase difference between the two crystal oscillators? Could you please give a very brief description of the principle behind the control logic? (I'm mostly a software guy and can't read schematics as easily as I'd like).

Thanks,

David.

ps Just FYI, I believe there's a discrepancy in component numbering between the circuit schematic and BOM that you've posted: eg, the schematic has the receiver trans-impedance amp as IC4, but the BOM has it labelled as IC13. Just so you know...

pillan

#33
Oct 31, 2014, 09:20 am Last Edit: Oct 31, 2014, 10:25 am by pillan
hi
is it still possible to buy an assembled -OSLRF-01-  ?

also, why don't you use a phase difference approach instead of time of flight ?

if you get a modulated laser fire with a sinusoidal signal then you can measure the phase difference between the laser-fire and returning signal using phase detector chip like ad8302

may it sound cool ? better than measuring the time of flight using equivalent time sampling ?

mmladenov09

Is it possible to extend the measurement range of the OSLRF-01 to more than 9m. I suppose that the use of stronger laser diode right solution.

Miroslav

sergeiK

Hello,

What resolution (cm, mm?) is it possible to theoretically obtain using the OSLRF-01? I would like to have precision up to mm on measurements in the ranges 5m - 15m for a project do you think it is possible to tweak the OSLRF-01 in order to obtain such precision?

Thanks in advance!

derRam

Hello!

I find it awesome that you open-sourced this device! I checked your website lightware, but you dont have application examples (places/situations where it can be put to use). A similar type of device called LMS-500 from SICK (also from Leuze, Jenoptik, ifm etc) works on Time of flight LaserDistanceMeasurement in 2D and 3D and they have included some very good applications. Nevertheless, it has a drawback in tems of Wave divergence and the Scan rate(measurements/second = max 100 Hz covering 190°). Yes, they use a rotating mirror, which includes mechanical parts, but it can also be dont without one. Moreover, the light spot diameter is not appreciable as Wave divergence is 4,7 mili-radian for the high resolution type. For that, they charge few thousand Euros! (2000-6000 € depending on the manufacturer)
Kindly check the their product website to have a feel of possible applications... Market your project man, there is huge demand.

Cheers!
-derRam

alexmu


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