Yea, I wish!! I was fortunate to win one of the $100.00 ones on EBay for $60.00 shipped. Works fine. I originally bought it just because I could not pass up the deal. However, I have been pondering a radar/laser guided missile defense system for my Wild Thumper. I picked up a toy missile shooter that the missiles rotate and the base spins for $4.00 on Amazon. I would like to come up with a way to track my RC helicopter with my WT and have laser guided missiles shoot at it!!! Probably a pipe dream but what the heck!!!!
EDIT: I to am hoping to get a 3D printer soon. I have been thinking of selling my metal lathe to buy one. I never use the lathe but would have plenty of uses for a 3D printer!!!
Duane, what wonderful things will you do with your $350 toy? I have an inquiring mind and I simply must know.
My intention is to use for altitude control with my hexacopter, but I'll want to have a bit more confidence in my flying abilities and the hexacopter's reliability before I sent it aloft.
It rained much of the day here so I was only able to test the rangefinder with an overcast sky.
The SF02 Laser RangeFinder is really cool! It measured the house next door just fine (about 15m away). I could even point it towards the top of a big tree outside and get a meaningful measurement back (17 meters or so).
I aimed the rangefinder across our neighbor's yard to the house on the other side of their yard and got a measurement of around 35 meters. It almost seems eerie to be able to measure things so far away without any visible action taken. The laser pulse is not visible.
I didn't find my Joe Grand LRF until this evening so I didn't compare it in the overcast light but tomorrow, if the sun is shinning, I'll try to make a video comparing a couple of different range finding sensors.
I made a video showing the SF02 in action but YouTube ate it.
The just of is was the SF02 rocks! The little Grand Idea LRF is fun (and has a cool laser) but it doesn't work well in bright light. Even an overcast sky is too much for the LRF.
The SF02 reads anything anywhere. It's amazing.
One thing I noticed was the Propeller Activity Board wouldn't read the SF02's signal from a servo port. The resistor in line apparently blocks the signal. I/O pins without a resistor read the SF02 just fine.
If you use an e-paper reader, you can see the output in direct sunlight. I use an OLPC with the Qi screen, it works great for testing.
I found that a retro reflective target (the stop sign at the end of the block or a licence plate driving by) are easiest to aquire.
Other targets, including an orthogonal flat wall, can have a range of valid readings. This is due to some points being closer, and some points being further from the sensor. A target like a bush or an evergreen tree can generate a lot of readings, some from the leaves closest to the sensor, and some from the trunk, and some from the branches on the other side. So I had to figure out a bunch of stuff about "noisy data" to get a feel for how to use the readings. When we look at a car, we think "its about X meters away". But some points are closest, and otther points can be three or four meters further away. Since the SF02 takes many measurements to generate a single reading, the numbers might seem to bounce around, since the readins are centimeters and the car is meters long. The readings appear to be correct, we just have to know how to use this type of data.
Makes me think about range to target in a whole different perspective. Very fun.
Has anyone tried this sensor over water - we are hoping to read the contour of waves on the sea pointing vertically down from pier - over a distance of around 10m
Anyone got an relevent experience with this sensor that might be relevant.
I'd be very surprised if the sensor didn't work great over water. I'm not sure how well it would be able to "read the contour of waves" since the sensor's maximum refresh rate is 12Hz. This might be fast enough to measure nice smooth rolling waves, but I doubt you'd be able to measure the shape of a breaking wave.
Realise won't be able to draw detail for a breaking wave, especially if it is on the cusp of breaking (and there is an overhang). The sensor will be out on the end of a pier so should be mostly smooth waves/swell, but we want to read the ups and downs of that rather than average overall tidal height.
Just wondered if anyone had tried it over water, especially over water that isn't perfectly flat (like a tank level reading would be).
remember, it collects a bunch of individual signals, and creates a single reading. The surface of the water represents a LOT of distances, depending on the angle of the light returning from the surface. The laser pulse going out is a cone, and any point on the surface that is covered by that cone could be the distance measured. So your measurement will be the "between the closest point, and the fartherst point.
Just wondered if anyone had tried it over water, especially over water that isn't perfectly flat (like a tank level reading would be).
I haven't tried this but I'd be very surprised if it couldn't read the distance to the water. If I can find a big enough body of water I'll give this a try.
i tried to make a video, you can see the laser as purple using cell phone camera. but the vid is too big to upload. maybe duane can do it better. any way, it measured the creek (and the duck) exactly as i measures a wall. if yo hold still, thes last digit changes. if you stand up you hand shakes and all the digits jump around. i thnk the beam is just couple degrees. ok gotta eat.
Any idea what the angle of this cone is? I'd think the lens used would keep the cone relatively narrow..
Very, very small. I have another laser distance measurer, a Bosch. I can shoot the beam through a 1" opening which is several feet away to measure something tens of feet further away - hand held. I was just playing around with it, it was not a careful test. I also used it to see if I could measure the distance to the corner of a room. In my rough tests, the spot being measured corresponded to the size of the spot made by the red aiming laser.
Very, very small. I have another laser distance measurer, a Bosch. .... the spot being measured corresponded to the size of the spot made by the red aiming laser.
I would advise that a Bosch red aiming laser is NOT so similar to SF02. The SF02 transmitter has a 2 cm lens to spread the beam. The SF02 recieve has a 2 cm lens to magnify the return signal (like a telescope).
If you look through a telescope, how far are the points you are seeing? If you are looking at for example a 6 inch pipe, some points are in the center of the pipe (closest to you) and some are at the "horizon" at each edge. So the edge point will be about 3 inches further away. So measurements in a 3 inch spread represent the eact distannce to the pipe.
The SF02 transmitter has a 2 cm lens to spread the beam. The SF02 recieve has a 2 cm lens to magnify the return signal (like a telescope).
I don't understand why they would want to spread the beam, kind of defeats the purpose of using a laser. Unless you mean expand, that makes sense. A beam expander increases the diameter of the beam while decreasing it's divergence, making it even less cone-like. Which is even better suited for measuring a precise spot.
If you google SF02 laser diode, you will find a post where somebody claims to know what laser diode it uses (some Omron part number I think, I don't remember exactly). If you google that part number, you'll find a data sheet that specifies something like 15 degrees divergence, which isn't all that narrow. Of course, maybe that isn't the actual part that's used.
Here is the thread where the creator discusses the design of the SF02. He specifically states that the lens is to collimate the beam but I did not find any details on how big the spot size is.
If you look in the sf02 thread on this forum you will find ALL the information on the SF02. The omron laser is the 14 watt (equivalent continous) unit. It is pulsed so the actual output is less than a regular laser pointer. Bcause the individual pulse is so bright the beam is spread out, this allows the spot to be wide enough to be detected by the "telscope" reciever. The spread of the beam and the magnification of the telescope are match for maximum effect. The laser, the lensing, and the avalanche photo diode are why this unit works so much better than any other option, and costs a bit more.
Bcause the individual pulse is so bright the beam is spread out, this allows the spot to be wide enough to be detected by the "telscope" reciever. The spread of the beam and the magnification of the telescope are match for maximum effect. The laser, the lensing, and the avalanche photo diode are why this unit works so much better than any other option, and costs a bit more.
I think you are misunderstanding what it means by spreading the beam out. The laser diode that is used does not make a narrow beam like a laser pointer, but a beam that is spread out in a wide fan shape. The lens is there to redirect that wide beam and collimate it, sending all the photons in the same direction parallel to each other in a beam that has a relatively wide diameter. I have not seen any data as to the divergence of this collimated beam. The only thing we know for sure is that the lens makes the beam less spread out. See below;
I'm sure many of you are wondering why the laser doesn't produce a nice parallel beam to start with, after all, that's what we see in the movies and the old HeNe lasers used to do it. The answer lies in the structure of semiconductor laser chips which, because of their small size, don't have a sufficiently long optical resonance cavity to make a parallel beam. Instead, they all produce a beam with a distorted cone shape and they all need a lens to make the beam parallel.
The only thing we know for sure is that the lens makes the beam less spread out. See below;
For what it's worth, this is also my understanding of the purpose of the lens.
I'll need to connect my sensor to a Prop again (I stole the Activity Board I was using to change a BOE-Bot into an ActivityBot) and figure out how tight this beam is.
I think you are misunderstanding what it means by spreading the beam out. The laser diode that is used does not make a narrow beam like a laser pointer, but a beam that is spread out in a wide fan shape. The lens is there to redirect that wide beam and collimate it, sending all the photons in the same direction parallel to each other in a beam that has a relatively wide diameter. I have not seen any data as to the divergence of this collimated beam. The only thing we know for sure is that the lens makes the beam less spread out.
Exactly right. Not to argue, "less spread out" is still spread out, as in "not a teeny dot like a red laser pointer".
If you use a camera to look at the emitter, you can see how wide the beam is.
RE posts 40 and 42, the SR02 would measure the range of highest and lowest distances to the water as each wave rolls by. So he could count waves and wave height, within a few centimeters.
If you use a camera to look at the emitter, you can see how wide the beam is.
Can you use a camera to see the spot that is being projected?
This whole "argument" started when you said "The SF02 transmitter has a 2 cm lens to spread the beam.". My point is that the lens actually does the opposite. It stops the spread and redirects the laser so that it is in a collimated beam - a beam with a diameter that is large compared to laser pointers so that the laser energy is "spread" over a wider area, but not spread in the sense that makes a cone shaped beam. The beam without the lens is extremely cone shaped (flattened cone), the lens corrects that and makes it straight.
Technically, all laser beams are cone shaped because there will always be divergence. The missing information with regards to the SF02 is how much divergence there is after the lens has collimated the beam. If you can photo the spot made by the beam at a known distance then we could get an answer.
Thanks for previous responses and tests. Reporting back after test over Thames yesterday. Got acceptable results, a clear trace of the swell from passing boats, at a distance of around 7m.
Next stage is to fix it on the pier. Is there any information available or known about how well the laser stands up to being outdoors 24/7 (rather than taken outside for short use) - is condensation on or inside the lens a problem etc... Any idea how long it is likely to survive a cold damp enviroment. My current plan is an ip67 box with lens just protruding, flexible sealant round the barrels to seal against water, and a wide tube extending as far as can without interfering with beam to keep rain from directly hitting it, or is it better to put it behind a window - would be concerned that that is just another surface to get condensation on, and if it did it would register as the distance rather than the one I want to read.
Comments
EDIT: I to am hoping to get a 3D printer soon. I have been thinking of selling my metal lathe to buy one. I never use the lathe but would have plenty of uses for a 3D printer!!!
My intention is to use for altitude control with my hexacopter, but I'll want to have a bit more confidence in my flying abilities and the hexacopter's reliability before I sent it aloft.
I had forgotten about this thread. Please keep us posted about sunlight usage.
The SF02 Laser RangeFinder is really cool! It measured the house next door just fine (about 15m away). I could even point it towards the top of a big tree outside and get a meaningful measurement back (17 meters or so).
I aimed the rangefinder across our neighbor's yard to the house on the other side of their yard and got a measurement of around 35 meters. It almost seems eerie to be able to measure things so far away without any visible action taken. The laser pulse is not visible.
I didn't find my Joe Grand LRF until this evening so I didn't compare it in the overcast light but tomorrow, if the sun is shinning, I'll try to make a video comparing a couple of different range finding sensors.
The just of is was the SF02 rocks! The little Grand Idea LRF is fun (and has a cool laser) but it doesn't work well in bright light. Even an overcast sky is too much for the LRF.
The SF02 reads anything anywhere. It's amazing.
One thing I noticed was the Propeller Activity Board wouldn't read the SF02's signal from a servo port. The resistor in line apparently blocks the signal. I/O pins without a resistor read the SF02 just fine.
Apparently YouTube finally finished "processing" the video.
Here are the rangefinder in action measuring the distance to the dinning room cupboards.
I tried making a video with the rangefinders outside in the sun but I couldn't see the LED displays in the sunlight.
As I've mentioned several times, the SF02 doesn't have any trouble measuring distance in the sunlight. It works really well.
I found that a retro reflective target (the stop sign at the end of the block or a licence plate driving by) are easiest to aquire.
Other targets, including an orthogonal flat wall, can have a range of valid readings. This is due to some points being closer, and some points being further from the sensor. A target like a bush or an evergreen tree can generate a lot of readings, some from the leaves closest to the sensor, and some from the trunk, and some from the branches on the other side. So I had to figure out a bunch of stuff about "noisy data" to get a feel for how to use the readings. When we look at a car, we think "its about X meters away". But some points are closest, and otther points can be three or four meters further away. Since the SF02 takes many measurements to generate a single reading, the numbers might seem to bounce around, since the readins are centimeters and the car is meters long. The readings appear to be correct, we just have to know how to use this type of data.
Makes me think about range to target in a whole different perspective. Very fun.
Anyone got an relevent experience with this sensor that might be relevant.
Thanks
Nick
I'd be very surprised if the sensor didn't work great over water. I'm not sure how well it would be able to "read the contour of waves" since the sensor's maximum refresh rate is 12Hz. This might be fast enough to measure nice smooth rolling waves, but I doubt you'd be able to measure the shape of a breaking wave.
Realise won't be able to draw detail for a breaking wave, especially if it is on the cusp of breaking (and there is an overhang). The sensor will be out on the end of a pier so should be mostly smooth waves/swell, but we want to read the ups and downs of that rather than average overall tidal height.
Just wondered if anyone had tried it over water, especially over water that isn't perfectly flat (like a tank level reading would be).
I haven't tried this but I'd be very surprised if it couldn't read the distance to the water. If I can find a big enough body of water I'll give this a try.
Any idea what the angle of this cone is? I'd think the lens used would keep the cone relatively narrow.
I'll try to figure out some way of testing this cone angle and see if I can find some water to measure.
Will report back my findings.
Have a good weekend
Nick
Very, very small. I have another laser distance measurer, a Bosch. I can shoot the beam through a 1" opening which is several feet away to measure something tens of feet further away - hand held. I was just playing around with it, it was not a careful test. I also used it to see if I could measure the distance to the corner of a room. In my rough tests, the spot being measured corresponded to the size of the spot made by the red aiming laser.
I would advise that a Bosch red aiming laser is NOT so similar to SF02. The SF02 transmitter has a 2 cm lens to spread the beam. The SF02 recieve has a 2 cm lens to magnify the return signal (like a telescope).
If you look through a telescope, how far are the points you are seeing? If you are looking at for example a 6 inch pipe, some points are in the center of the pipe (closest to you) and some are at the "horizon" at each edge. So the edge point will be about 3 inches further away. So measurements in a 3 inch spread represent the eact distannce to the pipe.
I don't understand why they would want to spread the beam, kind of defeats the purpose of using a laser. Unless you mean expand, that makes sense. A beam expander increases the diameter of the beam while decreasing it's divergence, making it even less cone-like. Which is even better suited for measuring a precise spot.
http://forums.hackaday.com/viewtopic.php?f=3&t=3490
I think you are misunderstanding what it means by spreading the beam out. The laser diode that is used does not make a narrow beam like a laser pointer, but a beam that is spread out in a wide fan shape. The lens is there to redirect that wide beam and collimate it, sending all the photons in the same direction parallel to each other in a beam that has a relatively wide diameter. I have not seen any data as to the divergence of this collimated beam. The only thing we know for sure is that the lens makes the beam less spread out. See below;
For what it's worth, this is also my understanding of the purpose of the lens.
I'll need to connect my sensor to a Prop again (I stole the Activity Board I was using to change a BOE-Bot into an ActivityBot) and figure out how tight this beam is.
Exactly right. Not to argue, "less spread out" is still spread out, as in "not a teeny dot like a red laser pointer".
If you use a camera to look at the emitter, you can see how wide the beam is.
RE posts 40 and 42, the SR02 would measure the range of highest and lowest distances to the water as each wave rolls by. So he could count waves and wave height, within a few centimeters.
Can you use a camera to see the spot that is being projected?
This whole "argument" started when you said "The SF02 transmitter has a 2 cm lens to spread the beam.". My point is that the lens actually does the opposite. It stops the spread and redirects the laser so that it is in a collimated beam - a beam with a diameter that is large compared to laser pointers so that the laser energy is "spread" over a wider area, but not spread in the sense that makes a cone shaped beam. The beam without the lens is extremely cone shaped (flattened cone), the lens corrects that and makes it straight.
Technically, all laser beams are cone shaped because there will always be divergence. The missing information with regards to the SF02 is how much divergence there is after the lens has collimated the beam. If you can photo the spot made by the beam at a known distance then we could get an answer.
Next stage is to fix it on the pier. Is there any information available or known about how well the laser stands up to being outdoors 24/7 (rather than taken outside for short use) - is condensation on or inside the lens a problem etc... Any idea how long it is likely to survive a cold damp enviroment. My current plan is an ip67 box with lens just protruding, flexible sealant round the barrels to seal against water, and a wide tube extending as far as can without interfering with beam to keep rain from directly hitting it, or is it better to put it behind a window - would be concerned that that is just another surface to get condensation on, and if it did it would register as the distance rather than the one I want to read.
Nick