# looking Long range laser rangefinder sensor.

#### strantor

Joined Oct 3, 2010
5,967
I need a long range (500+ yards/meters) laser rangefinder that I can integrate with a project. Preferably UART/SPI/whatever, but if there's only analog I'll take it.

<rant>
I thought this was old & inexpensive technology, piece of (cheap) cake. But I cannot seem to find a sensor to save my life. Mouser only has two avaliable with a range of 200+m. Digikey only has two rated 100+m. Sparkfun is no help. Scrolling through Adafruit's animated list of offerings I have to laugh at all these clips of someone measuring the distance from their hand to breadboard; What the heck do you use that for?! And if you're just measuring 1-2ft why not use much cheaper ultrasonics? Why is there such a flood of these wimpy Lidar sensors and why do the ones with any respectable range cost so much? And if respectable range is so expensive, how does this 800yd handheld rangefinder on Amazon cost only $42? What is it about these finished products (handheld rangefinders for golfing/sporting that have been around for ages) that makes them inexpensive? And how can I achieve the same? </rant> Is there any way to hack a cheap handheld and pull data out of it? I'd really rather not, but I will, if it's possible and if there's no alternative. I'd really rather use the cheap (if not millimeter accurate) laser rangefinder sensor that I expect to exist. You know, like the one inside the$42 rangefinder. Where is it? Am I just not using the right keywords? Is there a simple circuit I could build?

EDIT: I guess I should specify the accuracy I'm after. Doesn't have to be that precise. +/- 10% maybe.

#### Ya’akov

Joined Jan 27, 2019
5,659
I'll admit this looks somewhat dodgy but this.

#### strantor

Joined Oct 3, 2010
5,967
I'll admit this looks somewhat dodgy but this.
I did see that one, or one that looked just like it on ebay. The one I saw claimed to have a 1W laser which seemed excessive. The one you linked to claims a 50W laser! Whatever the case I don't see why such a powerful laser is required. The sporting rangefinder runs on a single CR2 battery. And why is it $150 coming from China? That implies a$500 price tag if coming from anywhere else. Still excessive technology and excessive price compared to what I expected to find.

I do appreciate your input and I may yet choose that device, dodgy as it is, because it's the closest thing I've seen to what I'm looking for. I feel like there is something big that I am missing. I just want that golf rangefinder technology but I don't know what to look for. I seriously doubt that the thing in the link is the same technology as what's in a golf rangefinder. I wish I knew what to google.

#### Ya’akov

Joined Jan 27, 2019
5,659
This might help some.

#### strantor

Joined Oct 3, 2010
5,967
This might help some.

Yes, I think it did. It helped me to reach the decision to just buy a cheap golf range finder and hack it into submission. It remains a mystery to me why it's so cheap when you buy the consumer product and so damned expensive when you try buy just the relevant bits, but they do seem to be the same technology. I'm sure I can get some kind of data out of it. Hopefully there is a nice clean serial signal on one if the pins inside that spells out the measured range, but if not, there is a ribbon cable going to that transparent LCD in the eyepiece and I feel pretty good about being able to highjack that. When I have succeeded maybe I should order 10k units from China, hack a serial output into them, and sell them at 1,500% markup.

#### MrSalts

Joined Apr 2, 2020
1,762
You can get a Lidar. Some surveying contour mapping lidars can do better than 4" resolution from an airplane at 1000-feet or more (through leaves). Look for Leddar Tech, Ouster, Velodyne, Continental Lidar Systems,

I'd wish you luck but I think you blocked me - so...

the iPhone13 Pro has a Lidar on board just in case you might already own one. It can't do the long range you want but, at least you get an idea of how it works.

how do you expect something that costs \$42 to measure a 1500 foot range. I assume you have no idea about multi-watt lasers, the safety, the optics required to focus IR beyond 1100 nm ("eye safe" is beyond 1500nm).

I guess my new signature line will become, "Everything is stupid until you take the effort to learn how challenges are overcome and understand the physics."

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#### MrSalts

Joined Apr 2, 2020
1,762
Quiz: if a laser is fired to a target 500m away, and it reflects off of a surface, is the light still coherent? What energy will a 2watt laser light have by the time it makes the full 1km round trip to a 1cm diameter receiving lens?
A) assume a the target is a person wearing a faded denim jacket
B) assume the target is a dog with black hair
C) assume the target is a natural limestone outcropping.

and, how much do you think it should cost?

#### DickCappels

Joined Aug 21, 2008
8,705
Please try to not derail this thread. You can start a new thread in Off Topic if you like.

#### strantor

Joined Oct 3, 2010
5,967
Please try to not derail this thread. You can start a new thread in Off Topic if you like.
What are you referring to? Everything seems perfectly on topic to me.

#### strantor

Joined Oct 3, 2010
5,967
I just ordered this. We will see what can be done about getting some data from it.

#### Ya’akov

Joined Jan 27, 2019
5,659
I just ordered this. We will see what can be done about getting some data from it.
Don't drop it in the woods.