Lasers in Measurements: Learn How to Use Them

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    Lasers Measurements
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Discussion Overview

The discussion revolves around the usage of lasers in measurements, exploring various applications, principles, and specific techniques such as laser triangulation and laser interferometry. Participants seek to understand how lasers can be utilized for measuring distances and other parameters in different contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about what to include in a presentation on laser measurements, specifically mentioning distance measurement as a starting point.
  • Another suggests using online resources to find information about laser distance theory, providing a link to an article.
  • A participant describes a specific application of lasers in measuring the speed of air in a hypersonic wind tunnel, detailing the use of a Class IV CO2 laser and the setup involving interference fringes.
  • Another participant mentions the broader applications of laser interferometry, including material damage analysis, and provides a link to further reading.
  • A participant asks for clarification on how laser triangulation works, outlining their understanding of the process involving reflection and projection onto a detector.
  • One participant recommends researching LIDAR systems for additional insights into laser measurement techniques.

Areas of Agreement / Disagreement

Participants generally agree that lasers have a wide range of applications in measurements, but there is no consensus on specific methods or principles, as various techniques and examples are discussed without resolution.

Contextual Notes

Some participants reference specific applications and principles without fully explaining the underlying assumptions or technical details, leaving certain aspects of the discussion open to interpretation.

Who May Find This Useful

This discussion may be useful for students or professionals interested in the applications of lasers in measurements, particularly those looking for examples and explanations of specific techniques like laser triangulation and interferometry.

fifi
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Hi! I have to make a presentation about the usage of lasers in measurements, but I am not sure what I should include. I thought of something like using laser beams for measuring distances, but I don't know how exactly this can be done and what else can be measured with lasers. I'd be greatful if you could help me :smile:
 
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My suggestion is that you go to google.com and enter "laser distance theory" or something similar (without the "theory" you get a lot sites of companies that manufacture lasers).
I did and got this interesting site:
http://www.sfgate.com/cgi-bin/article.cgifile=/chronicle/archive/2002/01/17/MN81755.DTL
 
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You obviously realize that there are lots of uses for lasers in measurement, but I think I have a particularly interesting application. I'm bound not to tell you too much about it, but I'm sure that if you thought about it then you'd be able to fill in the blanks.

Some researchers I know are currently using lasers to measure the speed of air in a hypersonic wind tunnel around an object which is designed fly through the air very, very quickly (~Mach 15, of the top of my head). A pretty powerful Class IV CO2 laser is split up into two parallel beams. I'm not too sure of the arrangement, (because I haven't been allowed to play with it..!), but using a system of mirrors/prisms one of these beams gets routed through the hypersonic air flow, and the other flows through stagnant air. The path lengths of the two beams is identical. The beams then meet up again, and the spacing of the resulting interference fringes (as recorded on some photographic film) is used to determine the speed of the moving air.
 
Yeah, googling for laser interferometry will bring up quite a number of applications from different fields in addition to the distance, displacement etc. measurements. We've used the thing for example in analysis of material damage & cracking in 3D ... gives you awesome resolution.

... about some of the principles in a tolerably interesting application :

http://www.ndt.net/article/v04n12/palles2/palles2.htm
 
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Thanks a lot! I really needed examples of what can be measured by lasers.
I have one more question. Do you know how laser triangulation works for mesuring distances? As far as I could understand from what I read, the laser beam is reflected by the target and then the target is projected on a detector by a lens. But how can we measure the distance to the target in this way?
 
It is probably worth doing a quick search on LIDAR systems as well.

Also, lots of commercial sites have basic information on the basic principles of operation of their products.

Claude.
 

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