From: wwm@wwmartin.net
On 12/6/25 14:00, john larkin wrote:
> On Sat, 6 Dec 2025 13:06:18 -0800, wmartin wrote:
>
>> Greetings,
>> Just musing here. How might I couple a fiber optic cable to the optical
>> window on a Lidar chip? Wondering if it's possible to do Lidar through a
>> twisty path, like routed around an arbitrary light blocking "thing". Are
>> there going to be intractable reflections at one or both ends of the
>> fiber? I do have a use for this if it is possible...
>> Regards,
>> Bill M.
>
> If the lidar chip has a window, and the beam is expanded to some
> modest diameter, you'd need a lens to get any amount of useful
> coupling.
>
> Got a link to the part?
>
> There are lots of cheap OTDRs around, so there must be
> fiber-compatible parts.
>
>
> John Larkin
> Highland Tech Glen Canyon Design Center
> Lunatic Fringe Electronics
The Lidar chip is ST VL53L4CD, a low power gadget for 1 to 1200mm
ranging. Nothing elegant, but it's cheap. I only need about 1.5" worth
of sensing range, just monitoring the position of an air cylinder shaft.
Yes, there are cylinders with built-in position read out, but I don't
get to use those...I'm looking at an add-on to existing installation(s).
I'm suspecting that the Lidar to fiber connection is not the real
problem here, the moving target reflector may be the bigger issue, I
can't introduce a critical mechanical alignment. It's going to get
shaken vigorously...in a race car. Looking into the optical fiber as a
way out of the also nasty electrical noise environment. Alternative is
to level shift the Lidar chip signals to 12v and mount the chip on the
air cylinder, not too keen on running an i2c bus over 3 or 4 feet of
cable at low level signal.
Anyway, just kicking around possiblities for now. Have a couple of the
Lidar chips to play with, that may drive the solution one direction or
another...or nowhere.
Thanks for the reply!
-bill
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