Laser Distance Meters

Wether in geodesics, in security systems, production controls or just on the golf corse - the measuring of distances with lasers or laserscanners is well established nowadays. The time - namely the time, the light needs to pass the needed distance - is the value to be determined. This sounds so simple, but it isn't - because the velocity of light is very, very high - it's 2.99792*108 m/s. In consequence one has to deal with very small times. In only one microsecond the passes 300 meters. A high resolution in place therefore demands highest resolution in time.

For pratical reasons the reflection mode is used. Tranceiver and receiver are placed in one device. For the distance to be measured we find d=c*t/2 with c=velocity of light. So if we take a distance of 1 kilometer, the time of flight will be 6.7µs. If the resolution has to 1cm we already need a time resolution of 67ps. TDC-GPX driven in M-Mode shows a peak-to-peak resolution very close to this. The resolution can be further improved by averaging without seeing any systematic errors from the TDC.

TDC Advantages

  • Direct conversion of time to digital values
  • Highest resolution: down to 10ps (70ps peak-to-peak)
  • Multichannel - TDC-GP1 and TDC-GP2 have two stop channels, TDC-GPX up to 8 channels
  • Multihit-capability - TDC-GP1 and TDC-GP2 can handle 4 Stops, TDC-GPX up to 32 Hits
  • High Update rates: TDC-GPX can measure with 200MHz peak rate
  • Direct pulse width measurement: TDC-GPX can directly measure the pulse width down to 1.5ns
  • Space savings: Single Chip-solution in a small QFN32, TQFP44 or TQFP100 package
  • Industrial operating range: from -40°C to +120°C.
  • Battery applications: for handheld devices a low current consumption is essential. Discover the TDC-GP2 - it's perfect for this! When you work in measuring range 2 with only one measurement plus calibration per second, the current consumption will be only 3uA for a 5V supply (Note: nearly the comlete consumption is delivered to the calibration clock)