That is a good summary of the technology approaches but take a look at the Acuity AR200 (https://www.acuitylaser.com/product/laser-sensors/short-range-sensors/ar200-laser-measurement-sensor/). It claims an accuracy of 12 microns (0.0005 inches) over distances of up to 100mm. I suspect that are more capable units from other vendors.
-----Original Message----- From: Chris Albertson <[email protected]> Sent: March 7, 2022 2:04 PM To: Enhanced Machine Controller (EMC) <[email protected]> Subject: Re: [Emc-users] Laser measurement sensor You can not get that kind of absolute precision with a time of light sensor. Even if you were willing to spend $100K. But you can measure relative distance MUCH finer than what you ask for. THis will tell you how foar the part moved. Maybe this is good enough? They measure relative distance by splitting the beam and sending one part to a mirror mounted to the moving part. The half-beam goes to the mirror and back then to a sensor, while the other half-beam goes directly to the sensor. The two beams interfere with each other as they add in phase and out of phase. The idea is to count the transitions from in to out of phase. Obviously this is not a cheap instrument, but hobbyists have built things like this. The time of flight sensor work by measuring the time it takes for light to travel the distance being measured. Light moves at about one foot per nanosecond. So to get "plus/minus one foot" accuracy, you need a clock that measures nanoseconds. If you can measure picoseconds, you are still only at the 0.01 inch level. There are better clocks but only in specialized laboratories. For home use on a normal budget "centimeter level" time of flight is about what you can get. There is one more optical technique. Basically it is triangulation. A laser projects a spot on the target and it is viewd from two different angles. There are many takes on this and some sensors are only a few dollars but they are over 1,000 time lass accurate then you want. These can be really cheap if you don't need 0.001". For example they use them in a grain silo looking down to measure how much grain is stored. Or even on a no-contact sink faucet to measure if your hand is under where the water would go. But for those things, centimeters are good enough. On Mon, Mar 7, 2022 at 9:47 AM Thaddeus Waldner <[email protected]> wrote: > Hi, > > I’m looking for a laser distance sensor with about 1-3 thousandths > resolution and about a 5-10” working range. > I wouldn’t mind buying a used unit. > > Does anyone here know of some brands/ models to check out? > > Google has pointed me at some Acuity products but I wondered if there > were other options besides that. > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
