Laser RangeFinders. Hamed Lotfizad Mehdi Modaresi Professor.. ...Dr. H.Tagirad

Transcription

1 Laser RangeFinders Hamed Lotfizad Mehdi Modaresi Professor.....Dr H.Tagirad

2 The Invention of the Laser The Invention of the Laser Invented in 1958 by Charles Townes and Arthur Schawlow of Bell Laboratories Was based on Einstein s s idea of the particle- wave duality of light, more than 30 years earlier

3 History of Laser Ranging In 1840 s, First remote sensing used with pigeons 1969, the first lunar laser ranging done by using reflectors placed on the moon by Apollo 11

4 Theory There are 3 types of laser distance measurements 1)Pulsed 2)Continuous wave 3)Interferometer Method Laser ranging is called LIDAR which stands for Light Detection and Ranging

5 Definitions Target Cooperative Target Uncooperative Target Retroreflection Diffuse Reflection Reflectance Response Time Depth of Field

6 Cooperative Targets

7 Non-cooperative Targets

8 Pulsed Laser Ranging Short duration and high power 1)Transmit pulse 2)Detect reflection 3)Measure time difference 4)Compute distance from speed of light

9 Pulsed Laser System

10 How to Compute the Distance 2R = C*Tr R = distance C = speed of light Tr = total travel time 30 cm over kilometers precision

11 Continuous Wave Frequency modulated laser ranging We know that: 1)Light travels in straight lines 2)Laser light is coherent 3)The speed of light is known Therefore we can compute the exact distance that the light has traveled

12 Beam-modulation Telemetry

13 How to Compute the RoundtripTime Tr = roundtrip time Phi r = phase Phi(r) was obtained from last diagram Now Tr calculates with this formula Then ϕ

14 How to Compute the Distance 2R = C*Tr R = distance C = speed of light Tr = total travel time 1 cm over kilometers precision

15 Factors affecting accuracy 1. Frequency of the tone or modulation. 2. Accuracy of the phase-measurement loop. This depends on signal strength, noise, and so on. 3. Stability of the modulation oscillator. 4. Number of cycles (or measurements) that can be averaged together for a range measurement. 5. Turbulence in the air through which the. measurement is made. 6. Variations in the index of refraction of the air.

16 Triangulation 1 Triangulation is a method of determining distance by using angles and trigonometry. 2.There are many different types of triangulation.

17 Some of Applications of LIDAR Satellite Systems (SLR) Sensing of Surface Elevations

18 Satellite Systems (SLR) Determine position of Earth s satellites Topography Oceanography Gravity Waves Plate Tectonics

19 Sensing of Surface Elevations

20 Rangefinders Uses pulses of infrared light Based on time difference from transmission to reception

21 Many Uses for Rangefinders Golf Hunting Architecture

22 GPS(Global Positioning System) GPS uses several satellites and the concept of triangulation. For this example there are satellites that are used to pinpoint the location of the transmitting vehicle on earth

23 Step 1 The vehicle determines how far away the first satellite is from it. Either pulsed or CW techniques can be used.

24 Step 2 The vehicle determines how far away a second satellite is from it.

25 Step 3 The vehicle determines how far away a third satellite is from it. Then it can combine all of the information and determine where on Earth it is located.

26 The Future of LIDAR In the future laser ranging will become more precise and cheaper, and many new applications will be implemented

27 Corporations and manufactures Acuity Research Freedom Technologies Sequence Vydas

28 AccuRange 200 laser displacement sensors AccuRange 4000 laser rangefinder AccuRange600 laser displacement sensors

29 AR200 Sensors Principles of Operation The AR200 sensors project a beam of visible laser light that creates a spot on a target surface. Reflected light from the surface is viewed from an angle by a line scan camera inside the AR200 sensor. The target s distance is computed from the image pixel data. The AR200 can not be overloaded and measures accurately even when a mirror reflects the entire light beam back to the detector. Likewise, on surfaces of polished glass or water, almost the entire beam passes through or is reflected away. The AR200 sensors can measure distance from the small remaining scattered light.

30 AccuRange600 laser displacement sensors Principles of Operation The AR600 sensors project a beam of visible laser light that creates a spot on a target surface. Reflected light from the surface is viewed from an angle by a line scan camera inside the AR600 sensor. The target s distance is computed from the image pixel data. The AR600 can not be overloaded and measures accurately even when a mirror reflects the entire light beam back to the detector. Likewise, on polished surfaces, almost the entire beam is reflected away. The AR600 sensors can measure distance from the small remaining scattered light.a

31 AccuRange 4000 laser rangefinder This sensor opeartes on "Time of flight" Principle.

32 Freedom Technologies PreciCura Series PreciCura sensor opeartes on Triangulation" Principle.

33 Different Types of applications

34 Sequence Technologies, Inc. ST263 DistoGAGE Laser Sensor Zero to 50 feet operating range for most surfaces 0.1 in (2.5mm) accuracy, 0.02 in (0.5mm) short- term repeatability Fast response time 50KHz maximum rate Lightweight, compact, low power design Tightly collimated output beam for small spot size

35 Comparison Between Different types of distance sensors 1.Inductive sensors

36 2.UltraSonic Sensors

37 3.Laser Distance Sensors

38 مطالعه در بازار ايران Searching for laser range sensor in Gomhory street : NOT FOUND!! Searching For laser rangefinder in lalehzar street : 15 m with 1cm accuracy 96,000 tomans Some Device with accuracy in mm -> > 650,000 tomans

39 Thanks. References: 1. AcuityResearch Corporation at 2. Sam s s Laser FAQ 3. Sequence Technologies. 3. Vydas Corp