Reliable distance measurement on poorly reflecting surfaces

The laser distance measurement sensor LDM302A is technically based on the versatile LDM301A. It has, however, especially been optimized for reliable distance measurements on poorly reflecting surfaces.

The proven time-of-flight measurement principle combines high resistance against ambient interferences with the safety of laser class 1. The high-energy, but very short laser pulses allow for measurements with centimeter precision and a high repetition rate.


The signal processing that has been changed compared against the LDM301A ensures reliable measurements up to 200 m without reflectors with a target reflectivity of only 6%.
The sensor can also be used in harsh industrial environments, such as ports or open cast mines due to the integrated heating and the protective housing according to protection class IP 67. The LDM302A offers the option to add visors or additional interfaces such as Profibus DP.


  • Positioning of vessels in docking support systems
  • Process monitoring in steel and rolling mills
  • Monitoring of conveying systems
  • Position control in mining


  • Large operating range on poorly reflecting surfaces without reflector
  • Laser-Time-of-Flight measurement allows for very short measuring times
  • Safe operation through invisible laser, class 1 laser
  • Integrated red pilot laser, optional visor for alignment
  • Programmable analog output 4 mA to 20 mA
  • Serial programming interfaces RS232 or RS422
  • Compact design, protection class IP 67
  • Customized parameterization via the PC software LDMTool
  • Easy installation and operation

Technical Data

Measuring range1 0.5 m ... 200 m for targets with poor reflectivity (< 10 %) 2,
with white target plate up to 3 km
Measurement uncertainty ±14 mm at 100Hz measuring rate and 10 Hz output rate
Resolution 1 mm
Measuring time 100 ms
Measuring range for velocity 0 m/s ... 100 m/s (measuring time 0.1 s to 0.5 s)3
Measuring laser

905 nm (infrared), laser class 1, EN 60825-1:2003-10

Pilot Laser 650 nm (visible red), laser class 2, ≤ 1 mW (on, off, flashing)
Operating temperature -40 °C ... +60 °C
Storage temperature -40 °C ... +70 °C
Supply voltage

10 VDC ... 30 VDC

Power consumption

< 5 W (operation without heating)
11.5 W (operation with heating 24 V)


RS 232 or RS 422, transmission rate 1.2 kBaud ... 460.8 kBaud, ASCII, 8N1
Programming with Windows terminal program (e.g. LDMTool or Hyper Terminal)

Switching outputs

2 x "high side" switches, output current max. 0.2 A, permanently short-circuit-proof, adjustable window function

Analog output

Programmable distance range limits, 4 mA ... 20 mA

Housing Aluminium anodized
Size (LxBxH) 136 mm x 57 mm x 104 mm
Weight ca. 800 g
Protection class IP 67
Shock resistance

10 g / 6 ms persistence shock DIN ISO 9022-3-31-01-1


13,000 hours (MIL HDBK 217 F N2

Remarks on the technical data of the LDM302A
1 depending on target reflectance, influence of extraneous light and atmospheric conditions
2 natural, diffuse reflecting surfaces; for targets under 10 m no poorly reflecting materials (dark/black surfaces)
3 Measuring distance to an object: 0.5 m...700 m


Mr. Daniel Strandt

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