LiDAR systems


Data examples


Contact details

Stream Line - cloud & boundary layer 
Research LiDAR

Stream LinePro - Boundary layer profiler Stream LineWind-Pro - mast replacement wind profiler Stream LinePro-Lo - Mast replacement and more Stream LineXR - long range Doppler LiDAR

The Stream Line XR Doppler LiDAR system is a compact, high resolution, high output power, 12km sampling Doppler LiDAR system. It offers the benefit of low power consumption, light weight and portable operation coupled with autonomous operation.  
- Field deployable
- Turn key operation
- Eye safe (Class 1M)
- Data logged in ASCII
- Real-time data acquisition to 12km
- Arbitrary scan patterns
- UPS power cut protection
- Mature, reliable technology
- Extended temperature option
- Flexible software
- Remote monitoring/control 
- UDP data broadcasting
- Gate overlapping - 3m range resolution.
- Email alerts
- Step/stare and continuous movement data acquisition

Typical applications:
- Cloud studies:
- Wind energy
- Air quality monitoring
- Pollution dispersion
- Gust monitoring
- Wind shear monitoring
- Boundary layer meteorology

- Airports:
- Wind profiles
- Vortex detection and tracking

- University research:
- PBL mapping
- Eddy dissipation rate
- Cloud research

- Environmental monitoring:
- City pollution mapping
- Air quality assessment
- Pollution dispersion
- Forest fire detection and tracking

- Meteorology:
- Wind profiling
- Visibility
- Boundary layer mixing height
- Scanning ceilometer

 - 130W at 24V DC
 - +/- 38m/s Doppler bandwidth 
 - 85Kg, 630 x 530 x 400mm
 - 12km measurement range / 100% duty
 - Up to 10Hz data acquisition to 12km
 - 50 or 100MHz sampling options
 - -20 to +45C operating temperature
 - Data broadcasting
 - Step / stare or continuous scanning modes
 - Unlimited scan patterns
 - Flexible software and scan scheduling
 - Raw data output
 - Synchronised operation with other units
 - 18m to 120m range gate selection


The Stream Line XR system has been in production since 2013, and was developed in-house by Halo Photonics. It is a repackaged version of the previous Stream Line model, containing the same well proven technology, but 25% smaller and 4x the optical power output.

A number of other improvements and updates accompanied the new system, and these are now standard options in both the XR and Stream Line models.

  • 100MHz sampling (option)
  • GPS module (standard)
  • Anti-backlash gearing (standard)
  • Extended temperature operation (option)
  • Synchronised operation with other units (standard)
  • Data acquisition at 10Hz to 12km (standard)
  • Acquisition during scanner movement (standard)
  • Fully programmable scan patterns - scanner position, acceleration and speed (standard)
  • Mixture of moving and step / stare scan patterns (standard)
  • Scans start with respect to time of day (standard)

The all-sky scanner of both the Stream Line and the XR incorporate a slip ring which allows unlimited rotation, and anti-backlash gearing for the highest possible accuracy.
User Selectable Range Gate length.
The software on all of our LiDAR systems allows for the selection of range-gate length. The temptation is usually to choose the shortest possible gate length in order to maximise the down-range measurement resolution. However, for longer range applications, a short range-gate length can result in a reduction in the achieved measurement range, and also a reduced accuracy Doppler estimate for each gate. 
Below is an example Doppler v. range display showing the same data set being processed firstly with 18m long range-gates, and then again with 90m gates. It can be seen, that the 90m gate processing is working to approximately twice the range of the exact same data set that was processed with 18m range-gates. The only difference here is the gate length being processed, and this highlights the trade off between range resolution, Doppler accuracy and overall range. 

The data being processed is the same for each instance, and was saved by the LiDAR as a raw data file. Raw data files produced by all of our LiDAR units are not fixed with respect to range gate, and can be re-processed with any length of range gate. 

During the post-processing routine, the spectrum of each range gate can also be logged - which may be useful for situations where spectral analysis is important. An example would be for wake vortex applications.


Gate Overlapping with Long Gates.
It is possible to achieve good results by combining long range gates and gate overlapping mode. The 3 images below show the same data file being processed with 3 different settings. 

(1) 18m gates. This results in a high resolution result, but some of the Doppler estimates are beginning to show signs of noise at the longer ranges.  
(2) 90m gates. The data appears to be quite pixelated and low resolution compared to the 18m gate version. The Doppler estimates look more consistant. 
(3) 90m overlapping gates. The resolution and detail has been improved from the 90m set, and the Doppler estimates look less noisy than in the 18m version. The minimum range has also been improved. 
LiDAR synchronising over a network.
The all-sky scanning StreamLine and StreamLine XR systems ship with free software that will allow them to be synchronised with other units. This is very useful for operating several LiDARs in dual or triple Doppler mode. 
A controller PC connects to the same network as the LiDARs, and co-ordinates data acquisition timing and scanner movement. The controller will log all of the commands and responses from each LiDAR, and will ensure that all timings are good to within less than 10mS. It is not important for each individual LiDAR to be set to exactly the same system time (because time can quickly drift on a PC), and so all acquisition and scanner movement is performed with respect to the controller's time. More details about this mode of operation can be sent on request.

More about gate overlapping.
High resolution data acquisition is possible with gate overlapping mode and the ability to select relatively short range gate lengths. With gate overlapping, successive groups of sample points are processed by advancing one point (3m at 50MHz sampling) for each new range gate rather than a whole range gate length.

In the example data shown above, gate overlapping is enabled for the first part of the capture, and then disabled after the break. The non-overlapped data appears to be quite pixelated compared to the overlapped part. It is possible to improve the appearance of long range-gate data by enabling gate overlapping. The LiDAR will process data more efficiently if longer gates are processed, but the overall resolution will appear coarse - and this is where overlapping can help.




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