Laser range finder help!

Discussion in 'The Projects Forum' started by Chris15, Jun 16, 2009.

  1. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    Hey
    I want to make some sort of circuit that will send an infrared, or normal red laser out and bounce back to a receiver to tell me the distance.

    If you cant tell me an answer dont worry, if you know any other military like or gun related circuits could you please share them with me.

    Thks Chris
     
  2. kurf

    Member

    Jun 15, 2009
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    Do some research on "Time of Flight", the most common method used with laser range finders.

    Using a laser might be a little more complicated then you wish to take on. I would use the ultrasonic range finder here: http://www.sparkfun.com/commerce/product_info.php?products_id=8502


    If you really need more precision then what this will give you then I would recommend trying a red LED and a transimpedance amp, a.k.a. current to voltage amp, as your receiver. The red LED should give you enough spectrum selectivity to receive the bounce of the laser. Put the LED in revered bias towards the inverting pin of the amplifier. Doing this will give you wider bandwidth and lower noise. This circuit is very sensitive to contaminates, and long leads on your components will also be a problem. I would use only surface mount parts and keep things tight. Good luck, I may try this one along with you. Sounds fun.
     
    Last edited: Jun 16, 2009
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    As far a TOF goes, I seem to recall that for radar (also electromagnetic radiation), it's about a mile per microsecond. You will need a very accurate timebase.
     
  4. ELECTRONERD

    Senior Member

    May 26, 2009
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    Interesting! If scientists were able to make them very accurate, they could send it on a sattelite and produce an computer generated image of the land structure on a planet from a sattelite without jeapordizing astronauts. Just a thought...
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    Google "radarsat". It's been done.
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Google FatMax by Stanley Tool. Yes, the same company that makes hammers and rulers.

    I have the TLM100. It is laser-based TOF with +/- 1/4 inch at 100 ft. Brand new, $50 on ebay. More expensive models claim as little as 1/16" at 600 ft (TLM300). It works and has a red laser dot for aiming (I believe the measuring laser is IR). Thus, you know what you are measuring, unlike with ultrasound. For example, you can measure the distance to a door knob, but not the door.

    John
     
  7. kurf

    Member

    Jun 15, 2009
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    That's no fun. What will we learn? It's always disappointing to me that so many great ideas are already taken. Happens often to young engineers like me. :(
     
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    If you want to see further, stand on the shoulders of others who came before you.

    John
     
  9. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    ok thanks but would i be able to make this circuit my self? I have a fair bit of electronics skills
     
  10. beenthere

    Retired Moderator

    Apr 20, 2004
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    The measuring principle is the same as for radar. You're measuring time of flight of a pulse of electromagnetic radiation. Do some research and see if your skills are developed enough (we can't possibly evaluate them).

    Modern land surveying equipment also use light. Some information plus operating principles should be locatable.
     
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