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I would like to develop a laser range-finder board similar to Extech DT300. I would like to achieve a centimeter precision at 20 meters.

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I don't know if devices such as DT300 use a "standard" time-of-flight approach (delta time between emission and reception) or a phase-shift time-of-flight approach (continuous emission, phase shift detection).

Question #1: Could ISL29501 achieve a similar precision? Datasheet is available here. The idea would be to use a laser emitter / receiver like here.

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Question #2: Should I use another chip to drive the laser emitter / receiver in a "standard" time-of-flight approach as described above?

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  • \$\begingroup\$ 325 mA drive seems adequate for limited ranges of 50m with the optimal,PD \$\endgroup\$ – Sunnyskyguy EE75 Oct 8 '16 at 19:00
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    \$\begingroup\$ DYI? Do yourself in? \$\endgroup\$ – Transistor Oct 8 '16 at 19:29
  • \$\begingroup\$ Title changed for typo... \$\endgroup\$ – John Smith Oct 8 '16 at 23:23
  • \$\begingroup\$ It does not use time-of-flight if you can afford it. It uses interferometry and a fixed (precision) light guide length inside it as a reference. \$\endgroup\$ – winny Nov 8 '16 at 8:47
  • \$\begingroup\$ @winny, Do you know of some place (link) that describes the theory of operation in more detail? \$\endgroup\$ – George Herold Dec 8 '16 at 18:04
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Your desired 10mm precision might be a bit optimistic. Here is the typical performance of their eval board with a ~2m range. It's not obvious to me how this changes when you increase the range.

Presumably there is a hard limit of ~33m due to the modulation frequency, but that's within your desired range.

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  • \$\begingroup\$ Thank you for pointing out the eval kit datasheet. But they are using an IR led. I guess that "most" of the precision comes from the emitter and the receptor, doesn't it? For sure, it would be very different with a laser. It seems difficult to know without testing... \$\endgroup\$ – John Smith Oct 8 '16 at 23:26
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    \$\begingroup\$ Hard to say. You are talking 67ps for 1cm (2cm round-trip) a lot of things could contribute to that. \$\endgroup\$ – Spehro Pefhany Oct 9 '16 at 0:14
  • \$\begingroup\$ I don't think this last comment is correct. ISL29501 doesn't measure the round-trip time to the target. It measures a shift in the phase. \$\endgroup\$ – John Smith Oct 9 '16 at 20:25
  • \$\begingroup\$ @JohnSmith How would you distinguish (say) a 370° phase shift from a 10° phase shift? \$\endgroup\$ – Spehro Pefhany Oct 9 '16 at 20:32

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