Laser Instruments and Instrumentation

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Laser Radar Instrumentation depends on knowing the speed of light, approximately 0.3 meters per nanosecond. Using that constant it is calculated how far a returning light photon has travelled to and from an object: Distance= (Speed of Light x Time of Flight) / 2. It works as follows;

  1. Laser generates an optical pulse.
  2. Pulse is reflected off an object and returns to the system receiver.
  3. High-speed counter measures the time of flight from the start pulse to the return pulse.
  4. Time measurement is converted to a distance by using the formula above

Laser Technology is utilised in accurate Laser Instruments for Industrial Level and Measurement Applications.

Reflectivity of the Object

Measurements are not generally affected by the reflectivity of the Object . Highly reflective objects may saturate some laser detectors, while the return signal from low-reflectivity objects may occasionally be too weak to register as valid.

Day or Night

Laser radar is an "active illumination" technique that, unlike photography, does not depend on ambient illumination. It works during the day or at night.

Sunlight and Reflections/Angle of Measurement

A strong sunlight reflection off a highly reflective target may "saturate" a receiver, producing an invalid or less accurate reading. However, laser measurements are not usually affected by other reflections.

Dust and Vapour

Laser measurements can be weakened by interacting with dust and vapour particles, which scatter the laser beam and the signal returning from the target. However, using last-pulse measurements can reduce or eliminate this interference.

Target's Angle of Repose

Laser measurements can be made to targets at any angle.

Background Noise and Radiation

Laser Measurement is not affected by background noise. Instrumentation generally determines baseline radiation levels to ensure that it does not interfere with measurements.

Temperature and Temperature Variations

Laser measurements are based on the speed of light and are unaffected by temperature variations.

Vessel Pressure and Off-Gas Layers

Laser Measurement is unaffected by pressure or vacuum variations, or off-gas layers.

Thanks to OPTEK for the above information.


Laser Level Instrumentation and Measurement

Introduction to Laser Instruments and Applications - When the laser was invented in 1960, it was amazingly, a solution looking for a problem. While the laser's weapons potential was clear, most of the uses of lasers that have changed the World were not foreseen even by the so-called experts of the time. In this chapter, we touch on perhaps one tenth of one percent of those where lasers are now indispensable, or at least have the potential to be in the future - from repairfaq.

Lasers come to Level Measurement - Laser-level technology is expanding options in sensor applications and this article covers the good and bad points of this new measurement technique.From David W. Spitzer and

Laser Level Measurement - David W. Spitzer - The basics, a short description - Part 1 and Part 2 - from appliedmc.

The Lowdown on Radar Level Measurement - Free-Air or Guided-Wave - Which Do You Use When? - Walt Boyes - Radar level measurement is basically divided into two groups, free-air and guided-wave - from the excellent Control Global.

Application Considerations for Continuous Level and Inventory Monitoring of Powder and Bulk Solids - Continuous level measurement is about one thing, e.g. answering the question “how much stuff do I have”. There are many applications where you need to know how much material is in a bin, silo or other vessel type. Usually the desired engineering unit is expressed in terms of volume or weight. “Measuring” volume or weight is not always the most practical approach, sometimes it isn’t even viable. Take those silos you have, how do you weigh the ingredients if the silos weren’t installed with load systems? Not an easy or inexpensive question to answer. So what do we do? This is where continuous level measurement sensors and systems come into play and offer a viable and cost effective approach.The purpose of this white paper is to discuss and inform about the application considerations when you need to measure the level of material continuously or simply determine on a continuous basis how much stuff you have in your vessels - whilst this document is about many of the technologies available it does have a section on Laser level - from Blue Level Technologies.

A Dozen Ways to Measure Fluid Level - How They Work - This article from ABB covers most level measurement techniques, however there is a small section on Laser Instrumentation for the Process Industry on page 6. 

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