On 13/08/2022 18:42, Phil Hobbs wrote:> > The usual method is a time-to-amplitude converter. > > Cheers > > Phil Hobbs >TI make some nice chips, you can even buy them: TDC7201, TDC7200 Resolution: 55 ps • Standard Deviation: 35 ps • Measurement Range: – Mode 1: 12 ns to 500 ns – Mode 2: 250 ns to 8 ms It needs a 16MHz input clock, work it out before you look at the data sheet. MK
How laser rangefinder or laser distance meter work and what chip can measure Time of Flight ?
Started by ●August 12, 2022
Reply by ●August 14, 20222022-08-14
Reply by ●August 14, 20222022-08-14
On Sat, 13 Aug 2022 13:42:30 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>Ed Lee wrote: >> On Friday, August 12, 2022 at 3:40:38 PM UTC-7, a a wrote: >>> On Friday, 12 August 2022 at 23:58:11 UTC+2, Ed Lee wrote: >>>> On Friday, August 12, 2022 at 2:31:31 PM UTC-7, a a wrote: >>>>> On Friday, 12 August 2022 at 22:37:28 UTC+2, Ed Lee wrote: >>>>>> On Friday, August 12, 2022 at 1:06:35 PM UTC-7, a a wrote: >>>>>>> On Friday, 12 August 2022 at 21:55:26 UTC+2, Ed Lee wrote: >>>>>>>> On Friday, August 12, 2022 at 11:45:18 AM UTC-7, a a wrote: >>>>>>>>> On Friday, 12 August 2022 at 15:46:11 UTC+2, Ed Lee wrote: >>>>>>>>>> On Friday, August 12, 2022 at 3:23:57 AM UTC-7, a a wrote: >>>>>>>>>>> On Friday, 12 August 2022 at 12:18:44 UTC+2, a a wrote: >>>>>>>>>>>> what chip, clocked at what frequency, is used to measure Time of Flight of laser light at such short time intervals ? >>>>>>>>>> GHz ASIC >>>>>>>>>> 3E-9 second per meter >>>>>>>>> c = 299 792 458 m/s > >>> c = 300 000 000 m/s >>>>>>>>> >>>>>>>>> 3E-9 s/m x 300 000 000 m/s = 0.9 >>>>>>>>> >>>>>>>>> ok >>>>>>>>> but for 1 cm resolution >>>>>>>>> we need 100 x faster clock >>>>>>>>> >>>>>>>>> and for parallel analysis of point cloud 100 x 100 >>>>>>>>> we need 100 x 100 faster clock >>>>>>>>> >>>>>>>>> could you explain ? >>>>>>>> There is no point in measuring all 10,000 points all at once. >>>>>>> so do you suggest, >>>>>>> what is marketed by iPhone and called Lidar in smartphone, >>>>>>> is a single point Laser Range Meter functionality ? >>>>>>> >>>>>>> If you are correct, so why do they present 2D laser scanner functionality on images ? >>>>>>> >>>>>>> Single point laser Lidar requires rotating head to work >>>>>>> >>>>>>> \so some kind od mechanics is involved >>>>>> Yes, precisely, to have better relative positioning with multi-sensors. However, there is no need to measure them all within E-9 second. >>>>> -E-9 second cloc k is for 1m resolution >>>>> for 1 cm resolution >>>>> you need >>>>> E-9 * 10-2 second clock >>>>> >>>>> but we still discuss a single-point operation >>>> With 5GHz (close to current fab cap) hardware counters, we can count pulses to the same point 100 times. If we get 25 pulses of 1 meter and 75 pulses of 1.1 meter, we can guess that the distance is close to 1.025 meters. >>>> >>>> Give me $100,000 and i can build you the chip to prove it. >>> -==c = 299 792 458 m/s > >>> c = 300 000 000 m/s >>> >>> -===3E-9 s/m x 300 000 000 m/s = 0.9 >>> >>> 300 000 000 m/s = 100 * 300 000 000 cm/s >>> >>> = 30 000 000 000 cm/s >>> >>> so you need 30 GHz clock x 2 to get 1 cm resolution for a single point >> >> 3GHz (reasonable clock) for 10cm resolution. >> >>> ok, for 1 m distant object >>> 300 MHz x 2 clock can do the job >>> >>> but if you need mobile laser range meter to scan objects on the fly, to act as 2D scanner, >>> 1 cm counts and makes the difference >> >> https://en.wikipedia.org/wiki/Oversampling >> for higher resolution. >> > >The usual method is a time-to-amplitude converter. > >Cheers > >Phil HobbsOne way is to use a simple analog time stretcher and a modest-frequency counter.
Reply by ●August 14, 20222022-08-14
On Sunday, 14 August 2022 at 18:24:59 UTC+2, jla...@highlandsniptechnology.com wrote:> On Sat, 13 Aug 2022 13:42:30 -0400, Phil Hobbs > <pcdhSpamM...@electrooptical.net> wrote: > > >Ed Lee wrote: > >> On Friday, August 12, 2022 at 3:40:38 PM UTC-7, a a wrote: > >>> On Friday, 12 August 2022 at 23:58:11 UTC+2, Ed Lee wrote: > >>>> On Friday, August 12, 2022 at 2:31:31 PM UTC-7, a a wrote: > >>>>> On Friday, 12 August 2022 at 22:37:28 UTC+2, Ed Lee wrote: > >>>>>> On Friday, August 12, 2022 at 1:06:35 PM UTC-7, a a wrote: > >>>>>>> On Friday, 12 August 2022 at 21:55:26 UTC+2, Ed Lee wrote: > >>>>>>>> On Friday, August 12, 2022 at 11:45:18 AM UTC-7, a a wrote: > >>>>>>>>> On Friday, 12 August 2022 at 15:46:11 UTC+2, Ed Lee wrote: > >>>>>>>>>> On Friday, August 12, 2022 at 3:23:57 AM UTC-7, a a wrote: > >>>>>>>>>>> On Friday, 12 August 2022 at 12:18:44 UTC+2, a a wrote: > >>>>>>>>>>>> what chip, clocked at what frequency, is used to measure Time of Flight of laser light at such short time intervals ? > >>>>>>>>>> GHz ASIC > >>>>>>>>>> 3E-9 second per meter > >>>>>>>>> c = 299 792 458 m/s > >>> c = 300 000 000 m/s > >>>>>>>>> > >>>>>>>>> 3E-9 s/m x 300 000 000 m/s = 0.9 > >>>>>>>>> > >>>>>>>>> ok > >>>>>>>>> but for 1 cm resolution > >>>>>>>>> we need 100 x faster clock > >>>>>>>>> > >>>>>>>>> and for parallel analysis of point cloud 100 x 100 > >>>>>>>>> we need 100 x 100 faster clock > >>>>>>>>> > >>>>>>>>> could you explain ? > >>>>>>>> There is no point in measuring all 10,000 points all at once. > >>>>>>> so do you suggest, > >>>>>>> what is marketed by iPhone and called Lidar in smartphone, > >>>>>>> is a single point Laser Range Meter functionality ? > >>>>>>> > >>>>>>> If you are correct, so why do they present 2D laser scanner functionality on images ? > >>>>>>> > >>>>>>> Single point laser Lidar requires rotating head to work > >>>>>>> > >>>>>>> \so some kind od mechanics is involved > >>>>>> Yes, precisely, to have better relative positioning with multi-sensors. However, there is no need to measure them all within E-9 second. > >>>>> -E-9 second cloc k is for 1m resolution > >>>>> for 1 cm resolution > >>>>> you need > >>>>> E-9 * 10-2 second clock > >>>>> > >>>>> but we still discuss a single-point operation > >>>> With 5GHz (close to current fab cap) hardware counters, we can count pulses to the same point 100 times. If we get 25 pulses of 1 meter and 75 pulses of 1.1 meter, we can guess that the distance is close to 1.025 meters. > >>>> > >>>> Give me $100,000 and i can build you the chip to prove it. > >>> -==c = 299 792 458 m/s > >>> c = 300 000 000 m/s > >>> > >>> -===3E-9 s/m x 300 000 000 m/s = 0.9 > >>> > >>> 300 000 000 m/s = 100 * 300 000 000 cm/s > >>> > >>> = 30 000 000 000 cm/s > >>> > >>> so you need 30 GHz clock x 2 to get 1 cm resolution for a single point > >> > >> 3GHz (reasonable clock) for 10cm resolution. > >> > >>> ok, for 1 m distant object > >>> 300 MHz x 2 clock can do the job > >>> > >>> but if you need mobile laser range meter to scan objects on the fly, to act as 2D scanner, > >>> 1 cm counts and makes the difference > >> > >> https://en.wikipedia.org/wiki/Oversampling > >> for higher resolution. > >> > > > >The usual method is a time-to-amplitude converter. > > > >Cheers > > > >Phil Hobbs > One way is to use a simple analog time stretcher and a > modest-frequency counter.just watched video kinect - sensor IR projection https://youtu.be/MlTf0yYQjSg?t=43 let me know if the projected IR points cloud is made of static preset points and what is a role of the pattern ? Can theory behing Kinect be turned into large scale indoor 3D scanner, replacing lenses in ca,meras, moving IR projector far from VGA camera to read depth at large distance ? Can IR pattern projected be replaced by another, higher IR power/ higher resolution pattern ?
Reply by ●August 15, 20222022-08-15
On Sunday, August 14, 2022 at 1:56:01 PM UTC-7, a a wrote:> On Sunday, 14 August 2022 at 18:24:59 UTC+2, jla...@highlandsniptechnology.com wrote: > > On Sat, 13 Aug 2022 13:42:30 -0400, Phil Hobbs > > <pcdhSpamM...@electrooptical.net> wrote: > > > > >Ed Lee wrote: > > >> On Friday, August 12, 2022 at 3:40:38 PM UTC-7, a a wrote: > > >>> On Friday, 12 August 2022 at 23:58:11 UTC+2, Ed Lee wrote: > > >>>> On Friday, August 12, 2022 at 2:31:31 PM UTC-7, a a wrote: > > >>>>> On Friday, 12 August 2022 at 22:37:28 UTC+2, Ed Lee wrote: > > >>>>>> On Friday, August 12, 2022 at 1:06:35 PM UTC-7, a a wrote: > > >>>>>>> On Friday, 12 August 2022 at 21:55:26 UTC+2, Ed Lee wrote: > > >>>>>>>> On Friday, August 12, 2022 at 11:45:18 AM UTC-7, a a wrote: > > >>>>>>>>> On Friday, 12 August 2022 at 15:46:11 UTC+2, Ed Lee wrote: > > >>>>>>>>>> On Friday, August 12, 2022 at 3:23:57 AM UTC-7, a a wrote: > > >>>>>>>>>>> On Friday, 12 August 2022 at 12:18:44 UTC+2, a a wrote: > > >>>>>>>>>>>> what chip, clocked at what frequency, is used to measure Time of Flight of laser light at such short time intervals ? > > >>>>>>>>>> GHz ASIC > > >>>>>>>>>> 3E-9 second per meter > > >>>>>>>>> c = 299 792 458 m/s > >>> c = 300 000 000 m/s > > >>>>>>>>> > > >>>>>>>>> 3E-9 s/m x 300 000 000 m/s = 0.9 > > >>>>>>>>> > > >>>>>>>>> ok > > >>>>>>>>> but for 1 cm resolution > > >>>>>>>>> we need 100 x faster clock > > >>>>>>>>> > > >>>>>>>>> and for parallel analysis of point cloud 100 x 100 > > >>>>>>>>> we need 100 x 100 faster clock > > >>>>>>>>> > > >>>>>>>>> could you explain ? > > >>>>>>>> There is no point in measuring all 10,000 points all at once. > > >>>>>>> so do you suggest, > > >>>>>>> what is marketed by iPhone and called Lidar in smartphone, > > >>>>>>> is a single point Laser Range Meter functionality ? > > >>>>>>> > > >>>>>>> If you are correct, so why do they present 2D laser scanner functionality on images ? > > >>>>>>> > > >>>>>>> Single point laser Lidar requires rotating head to work > > >>>>>>> > > >>>>>>> \so some kind od mechanics is involved > > >>>>>> Yes, precisely, to have better relative positioning with multi-sensors. However, there is no need to measure them all within E-9 second. > > >>>>> -E-9 second cloc k is for 1m resolution > > >>>>> for 1 cm resolution > > >>>>> you need > > >>>>> E-9 * 10-2 second clock > > >>>>> > > >>>>> but we still discuss a single-point operation > > >>>> With 5GHz (close to current fab cap) hardware counters, we can count pulses to the same point 100 times. If we get 25 pulses of 1 meter and 75 pulses of 1.1 meter, we can guess that the distance is close to 1.025 meters. > > >>>> > > >>>> Give me $100,000 and i can build you the chip to prove it. > > >>> -==c = 299 792 458 m/s > >>> c = 300 000 000 m/s > > >>> > > >>> -===3E-9 s/m x 300 000 000 m/s = 0.9 > > >>> > > >>> 300 000 000 m/s = 100 * 300 000 000 cm/s > > >>> > > >>> = 30 000 000 000 cm/s > > >>> > > >>> so you need 30 GHz clock x 2 to get 1 cm resolution for a single point > > >> > > >> 3GHz (reasonable clock) for 10cm resolution. > > >> > > >>> ok, for 1 m distant object > > >>> 300 MHz x 2 clock can do the job > > >>> > > >>> but if you need mobile laser range meter to scan objects on the fly, to act as 2D scanner, > > >>> 1 cm counts and makes the difference > > >> > > >> https://en.wikipedia.org/wiki/Oversampling > > >> for higher resolution. > > >> > > > > > >The usual method is a time-to-amplitude converter. > > > > > >Cheers > > > > > >Phil Hobbs > > One way is to use a simple analog time stretcher and a > > modest-frequency counter. > just watched video > > kinect - sensor IR projection > > https://youtu.be/MlTf0yYQjSg?t=43 > > let me know if the projected IR points cloud is made of static preset points > and what is a role of the pattern ? > > Can theory behing Kinect be turned into large scale indoor 3D scanner, > replacing lenses in ca,meras, > moving IR projector far from VGA camera to read depth at large distance ? > > Can IR pattern projected be replaced by another, higher IR power/ higher resolution pattern ?Nobody's talking, so i will. This IR stuff has nothing to do with measuring distance, unless you have to do it in the dark. If you are asking about 3D distance mapping, you have to enable it one at a time, even if you have a 100x100 laser matrix. As someone pointed out, you can buy existing chips. But if you are integrating it into laser matrix, you might have to build your own hardware counters and routing circuits. 5GHz counters can handle at least an inch or couple cm resolution, before oversampling. You can turn off most of the circuit except for fraction of a second, in order to save power.
Reply by ●August 15, 20222022-08-15
On Monday, 15 August 2022 at 14:51:32 UTC+2, Ed Lee wrote:> On Sunday, August 14, 2022 at 1:56:01 PM UTC-7, a a wrote: > > On Sunday, 14 August 2022 at 18:24:59 UTC+2, jla...@highlandsniptechnology.com wrote: > > > On Sat, 13 Aug 2022 13:42:30 -0400, Phil Hobbs > > > <pcdhSpamM...@electrooptical.net> wrote: > > > > > > >Ed Lee wrote: > > > >> On Friday, August 12, 2022 at 3:40:38 PM UTC-7, a a wrote: > > > >>> On Friday, 12 August 2022 at 23:58:11 UTC+2, Ed Lee wrote: > > > >>>> On Friday, August 12, 2022 at 2:31:31 PM UTC-7, a a wrote: > > > >>>>> On Friday, 12 August 2022 at 22:37:28 UTC+2, Ed Lee wrote: > > > >>>>>> On Friday, August 12, 2022 at 1:06:35 PM UTC-7, a a wrote: > > > >>>>>>> On Friday, 12 August 2022 at 21:55:26 UTC+2, Ed Lee wrote: > > > >>>>>>>> On Friday, August 12, 2022 at 11:45:18 AM UTC-7, a a wrote: > > > >>>>>>>>> On Friday, 12 August 2022 at 15:46:11 UTC+2, Ed Lee wrote: > > > >>>>>>>>>> On Friday, August 12, 2022 at 3:23:57 AM UTC-7, a a wrote: > > > >>>>>>>>>>> On Friday, 12 August 2022 at 12:18:44 UTC+2, a a wrote: > > > >>>>>>>>>>>> what chip, clocked at what frequency, is used to measure Time of Flight of laser light at such short time intervals ? > > > >>>>>>>>>> GHz ASIC > > > >>>>>>>>>> 3E-9 second per meter > > > >>>>>>>>> c = 299 792 458 m/s > >>> c = 300 000 000 m/s > > > >>>>>>>>> > > > >>>>>>>>> 3E-9 s/m x 300 000 000 m/s = 0.9 > > > >>>>>>>>> > > > >>>>>>>>> ok > > > >>>>>>>>> but for 1 cm resolution > > > >>>>>>>>> we need 100 x faster clock > > > >>>>>>>>> > > > >>>>>>>>> and for parallel analysis of point cloud 100 x 100 > > > >>>>>>>>> we need 100 x 100 faster clock > > > >>>>>>>>> > > > >>>>>>>>> could you explain ? > > > >>>>>>>> There is no point in measuring all 10,000 points all at once. > > > >>>>>>> so do you suggest, > > > >>>>>>> what is marketed by iPhone and called Lidar in smartphone, > > > >>>>>>> is a single point Laser Range Meter functionality ? > > > >>>>>>> > > > >>>>>>> If you are correct, so why do they present 2D laser scanner functionality on images ? > > > >>>>>>> > > > >>>>>>> Single point laser Lidar requires rotating head to work > > > >>>>>>> > > > >>>>>>> \so some kind od mechanics is involved > > > >>>>>> Yes, precisely, to have better relative positioning with multi-sensors. However, there is no need to measure them all within E-9 second. > > > >>>>> -E-9 second cloc k is for 1m resolution > > > >>>>> for 1 cm resolution > > > >>>>> you need > > > >>>>> E-9 * 10-2 second clock > > > >>>>> > > > >>>>> but we still discuss a single-point operation > > > >>>> With 5GHz (close to current fab cap) hardware counters, we can count pulses to the same point 100 times. If we get 25 pulses of 1 meter and 75 pulses of 1.1 meter, we can guess that the distance is close to 1.025 meters. > > > >>>> > > > >>>> Give me $100,000 and i can build you the chip to prove it. > > > >>> -==c = 299 792 458 m/s > >>> c = 300 000 000 m/s > > > >>> > > > >>> -===3E-9 s/m x 300 000 000 m/s = 0.9 > > > >>> > > > >>> 300 000 000 m/s = 100 * 300 000 000 cm/s > > > >>> > > > >>> = 30 000 000 000 cm/s > > > >>> > > > >>> so you need 30 GHz clock x 2 to get 1 cm resolution for a single point > > > >> > > > >> 3GHz (reasonable clock) for 10cm resolution. > > > >> > > > >>> ok, for 1 m distant object > > > >>> 300 MHz x 2 clock can do the job > > > >>> > > > >>> but if you need mobile laser range meter to scan objects on the fly, to act as 2D scanner, > > > >>> 1 cm counts and makes the difference > > > >> > > > >> https://en.wikipedia.org/wiki/Oversampling > > > >> for higher resolution. > > > >> > > > > > > > >The usual method is a time-to-amplitude converter. > > > > > > > >Cheers > > > > > > > >Phil Hobbs > > > One way is to use a simple analog time stretcher and a > > > modest-frequency counter. > > just watched video > > > > kinect - sensor IR projection > > > > https://youtu.be/MlTf0yYQjSg?t=43 > > > > let me know if the projected IR points cloud is made of static preset points > > and what is a role of the pattern ? > > > > Can theory behing Kinect be turned into large scale indoor 3D scanner, > > replacing lenses in ca,meras, > > moving IR projector far from VGA camera to read depth at large distance ? > > > > Can IR pattern projected be replaced by another, higher IR power/ higher resolution pattern ? > Nobody's talking, so i will. > > This IR stuff has nothing to do with measuring distance, unless you have to do it in the dark. If you are asking about 3D distance mapping, you have to enable it one at a time, even if you have a 100x100 laser matrix. > > As someone pointed out, you can buy existing chips. But if you are integrating it into laser matrix, you might have to build your own hardware counters and routing circuits. 5GHz counters can handle at least an inch or couple cm resolution, before oversampling. You can turn off most of the circuit except for fraction of a second, in order to save power.thank you I need to learn more about laser IR projector in Kinect "The Kinect infrared sensor sees the sofa as a large number of tiny dots. The Kinect sensor constantly projects these dots over the area in its view. If you want to view the dots yourself, it’s actually very easy; all you need is a video camera or camcorder that has a night vision mode. A camera in night vision mode is sensitive to the infrared light spectrum that the Kinect distance sensor uses. Figure 1-6, for example, was taken in complete darkness, with the sofa lit only by the Kinect. The infrared sensor in the Kinect is fitted with a filter that keeps out ordinary light, which is how it can see just the infrared dots, even in a brightly lit room. The dots are arranged in a pseudo-random pattern that is hardwired into the sensor. You can see some of the pattern in Figure 1-7. https://www.microsoftpressstore.com/articles/article.aspx?p=2201646 I need to know how pseudo-random pattern of dots is generated by IR laser projector Resolution is not low https://www.microsoftpressstore.com/content/images/chap1_9780735663961/elementLinks/httpatomoreillycomsourcemspimages1239382.jpg dots are not lined up so it seems to me some laser optics / lens is involved - single laser diode + lens with drilled pattern ? "pseudo-random pattern that is hardwired into the sensor. not sure what they mean, since to have pseudo-random[pattern hardwired into the sensor you need to get (x,y) coordinates for every single point I recall another algorithm to generate 3D depth images by moving camera, based on blur effect, since closer objects move faster in the plane perpendicular to the camera axis so if we stack a number of images/frames together, we get blur effect for the closer objects to intensify. ---- Kinect`s infrared projector in action 51,995 views 17 Nov 2010 37 Dislike Share Clip Save Vladimir Seregin 374 subscribers Video recorded with an regular webcam without IR filter on it. https://www.youtube.com/watch?v=brnIty7mh2Q since every single dot is clearly visible in regular HD webcam so a number of dots projected must be below HD resolution -- there is a number of web links but they refer to IR camera resolution only 640 x 480 The Kinect sensor returns 16 bits perpixel infrared data with a resolution of 640 x 480as an color image format, and it supports up to30 FPS. Following are the couple of images ( taken in a complete dark room) that captures from IR stream data. Get the IR Stream and control the IR Emitter – Kinect for Windows SDK ... abhijitjana.net/2013/01/11/get-the-ir-stream-and-control-the-ir-emitter-kinect-for-windows-sdk/ abhijitjana.net/2013/01/11/get-the-ir-stream-and-control-the-ir-emitter-kinect-for … Get the IR Stream and control the IR Emitter – Kinect for Windows SDK https://abhijitjana.net/2013/01/11/get-the-ir-stream-and-control-the-ir-emitter-kinect-for-windows-sdk/#:~:text=The%20Kinect%20sensor%20returns%2016%20bits%20perpixel%20infrared,dark%20room%29%20that%20captures%20from%20IR%20stream%20data.
Reply by ●August 15, 20222022-08-15
On Monday, 15 August 2022 at 14:51:32 UTC+2, Ed Lee wrote:> On Sunday, August 14, 2022 at 1:56:01 PM UTC-7, a a wrote: > > On Sunday, 14 August 2022 at 18:24:59 UTC+2, jla...@highlandsniptechnology.com wrote: > > > On Sat, 13 Aug 2022 13:42:30 -0400, Phil Hobbs > > > <pcdhSpamM...@electrooptical.net> wrote: > > > > > > >Ed Lee wrote: > > > >> On Friday, August 12, 2022 at 3:40:38 PM UTC-7, a a wrote: > > > >>> On Friday, 12 August 2022 at 23:58:11 UTC+2, Ed Lee wrote: > > > >>>> On Friday, August 12, 2022 at 2:31:31 PM UTC-7, a a wrote: > > > >>>>> On Friday, 12 August 2022 at 22:37:28 UTC+2, Ed Lee wrote: > > > >>>>>> On Friday, August 12, 2022 at 1:06:35 PM UTC-7, a a wrote: > > > >>>>>>> On Friday, 12 August 2022 at 21:55:26 UTC+2, Ed Lee wrote: > > > >>>>>>>> On Friday, August 12, 2022 at 11:45:18 AM UTC-7, a a wrote: > > > >>>>>>>>> On Friday, 12 August 2022 at 15:46:11 UTC+2, Ed Lee wrote: > > > >>>>>>>>>> On Friday, August 12, 2022 at 3:23:57 AM UTC-7, a a wrote: > > > >>>>>>>>>>> On Friday, 12 August 2022 at 12:18:44 UTC+2, a a wrote: > > > >>>>>>>>>>>> what chip, clocked at what frequency, is used to measure Time of Flight of laser light at such short time intervals ? > > > >>>>>>>>>> GHz ASIC > > > >>>>>>>>>> 3E-9 second per meter > > > >>>>>>>>> c = 299 792 458 m/s > >>> c = 300 000 000 m/s > > > >>>>>>>>> > > > >>>>>>>>> 3E-9 s/m x 300 000 000 m/s = 0.9 > > > >>>>>>>>> > > > >>>>>>>>> ok > > > >>>>>>>>> but for 1 cm resolution > > > >>>>>>>>> we need 100 x faster clock > > > >>>>>>>>> > > > >>>>>>>>> and for parallel analysis of point cloud 100 x 100 > > > >>>>>>>>> we need 100 x 100 faster clock > > > >>>>>>>>> > > > >>>>>>>>> could you explain ? > > > >>>>>>>> There is no point in measuring all 10,000 points all at once. > > > >>>>>>> so do you suggest, > > > >>>>>>> what is marketed by iPhone and called Lidar in smartphone, > > > >>>>>>> is a single point Laser Range Meter functionality ? > > > >>>>>>> > > > >>>>>>> If you are correct, so why do they present 2D laser scanner functionality on images ? > > > >>>>>>> > > > >>>>>>> Single point laser Lidar requires rotating head to work > > > >>>>>>> > > > >>>>>>> \so some kind od mechanics is involved > > > >>>>>> Yes, precisely, to have better relative positioning with multi-sensors. However, there is no need to measure them all within E-9 second. > > > >>>>> -E-9 second cloc k is for 1m resolution > > > >>>>> for 1 cm resolution > > > >>>>> you need > > > >>>>> E-9 * 10-2 second clock > > > >>>>> > > > >>>>> but we still discuss a single-point operation > > > >>>> With 5GHz (close to current fab cap) hardware counters, we can count pulses to the same point 100 times. If we get 25 pulses of 1 meter and 75 pulses of 1.1 meter, we can guess that the distance is close to 1.025 meters. > > > >>>> > > > >>>> Give me $100,000 and i can build you the chip to prove it. > > > >>> -==c = 299 792 458 m/s > >>> c = 300 000 000 m/s > > > >>> > > > >>> -===3E-9 s/m x 300 000 000 m/s = 0.9 > > > >>> > > > >>> 300 000 000 m/s = 100 * 300 000 000 cm/s > > > >>> > > > >>> = 30 000 000 000 cm/s > > > >>> > > > >>> so you need 30 GHz clock x 2 to get 1 cm resolution for a single point > > > >> > > > >> 3GHz (reasonable clock) for 10cm resolution. > > > >> > > > >>> ok, for 1 m distant object > > > >>> 300 MHz x 2 clock can do the job > > > >>> > > > >>> but if you need mobile laser range meter to scan objects on the fly, to act as 2D scanner, > > > >>> 1 cm counts and makes the difference > > > >> > > > >> https://en.wikipedia.org/wiki/Oversampling > > > >> for higher resolution. > > > >> > > > > > > > >The usual method is a time-to-amplitude converter. > > > > > > > >Cheers > > > > > > > >Phil Hobbs > > > One way is to use a simple analog time stretcher and a > > > modest-frequency counter. > > just watched video > > > > kinect - sensor IR projection > > > > https://youtu.be/MlTf0yYQjSg?t=43 > > > > let me know if the projected IR points cloud is made of static preset points > > and what is a role of the pattern ? > > > > Can theory behing Kinect be turned into large scale indoor 3D scanner, > > replacing lenses in ca,meras, > > moving IR projector far from VGA camera to read depth at large distance ? > > > > Can IR pattern projected be replaced by another, higher IR power/ higher resolution pattern ? > Nobody's talking, so i will. > > This IR stuff has nothing to do with measuring distance, unless you have to do it in the dark. If you are asking about 3D distance mapping, you have to enable it one at a time, even if you have a 100x100 laser matrix. > > As someone pointed out, you can buy existing chips. But if you are integrating it into laser matrix, you might have to build your own hardware counters and routing circuits. 5GHz counters can handle at least an inch or couple cm resolution, before oversampling. You can turn off most of the circuit except for fraction of a second, in order to save power.from https://www.dfki.de/fileadmin/user_upload/import/8767_wasenmuller2016comparison.pdf The Kinect v1 measures the depth with the Pattern Projection principle, where a known infrared pattern is projected into the scene and out of its distortion the depth is computed. The Kinect v2 contains a Time-of-Flight (ToF) camera and determines the depth by measuring the time emitted light takes from the camera to the object and back. Therefore, it constantly emits infrared light with modulated waves and detects the shifted phase of the returning light [17, 18]. In the following, we refer to both cameras (Pattern Projection and ToF) as depth camera not sure how ToF can be live implemented into 2D image analysis
