Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

B Is it possible to magnify light heat?

  1. May 18, 2016 #1
    Is it possible for me to make a flash light into a "laser" hot enough to burn through paper. Here is what I have: a light prism, 2 light splitters,(the can separate light so it goes 2 ways) 2 magnifying glasses, and a microscope.(I don't want to use it though) If there is any thing else you think I might have let me know. After you explain how to make it(if possible) can you explain why it works,... or why it doesn't. Thank in advance.
     
  2. jcsd
  3. May 18, 2016 #2

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    A huge portion of "light heat" (to use the phrase you adopted) is in the IR part of the spectrum. How much do you think this part of the spectrum is attenuated by all the optical elements that you intend to use?

    Zz.
     
  4. May 18, 2016 #3

    russ_watters

    User Avatar

    Staff: Mentor

    In principle yes, in practice you will need something much stronger than a battery operated flashlight.
     
  5. May 18, 2016 #4
    You can certainly burn paper using just the Sun and a simple magnifying glass.
     
  6. May 18, 2016 #5

    Nidum

    User Avatar
    Science Advisor
    Gold Member

  7. May 18, 2016 #6
    I know but I want to do is with a flash light in a dark room.
     
  8. May 18, 2016 #7

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Sunlight is more intense and better to focus than your typical flashlight.

    With sunlight and a magnifying glass with a diameter of 5 cm, you get ~2 W with a focal point of ~1 mm diameter. A bright flashlight might have that as total power output, but good luck focusing it to such a small spot. You won't be able to focus it better than the size of the emitter.
     
  9. May 18, 2016 #8
    I don't know I was hoping one of you could tell me. So far
    So I can't do it? What about a light house, how do the make the lights so bright? If I could magnify the light in a similar way, I could buy a big magnifying glass. or Could I use a laser pointer, the emitter will be tiny.
     
    Last edited by a moderator: May 18, 2016
  10. May 18, 2016 #9

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    There are probably flashlights with sufficient power. But where is the point? A proper laser (typical laser pointers won't have sufficient power I think) can do the same and doesn't need additional optics. And why does it have to be light to ignite paper?
    They don't use a battery-operated flashlight? They do not magnify light, they just use a much more powerful light source.
     
  11. May 18, 2016 #10
    what do you "attenuated"
    The first light house was one of the 7 wonders, it used a fire for the light source. It was as tall as a 44 story building, so they would have had to magnify it some how. Can you explain how this works?
     
  12. May 18, 2016 #11
    The reason I'm going through all this is because my science teacher said he would give extra points to anyone who can make a laser. To get into Harvard you have to have a GPA of at least 4.04.
     
  13. May 18, 2016 #12

    davenn

    User Avatar
    Science Advisor
    Gold Member

    I don't think you understand the difference between a normal light source and a laser light source
    and it seems all the posters above missed your laser comment in your first post as they didn't address it

    Tell me what you know about the difference between a normal light and a laser light source

    you are not going to make a laser light source at home ... as in modifying a torch or other lamp
    but you can buy a laser light source eg a laser diode and build up the electronics circuit around it to make it work
    ohhh and you will need some optics as well

    Dave
     
    Last edited: May 18, 2016
  14. May 18, 2016 #13
    I don't have any way to see invisible light, is there something I can download on my phone. How could I build up electrons around the laser circuit? (what does eg mean)

    I thought a laser was a pinpointed light. Thanks for the help. (and actually reading my question)
     
  15. May 18, 2016 #14

    davenn

    User Avatar
    Science Advisor
    Gold Member

    ? invisible light hasn't entered the conversation till now
    Tho you hinted at it with your oddly worded thread title :wink:
    IR ( Infra-red) light is invisible to us commonly used for remote controls

    electronics, not electrons. If you haven't done any electronics construction, then it may be a project out of your grasp at the moment till you learn a bit more

    here is an example of a laser diode ...
    the gold coloured bit is about 1cm in diameter
    th?&id=OIP.Mbff6ac6b2f4da619394fbd666c97e287H0&w=300&h=300&c=0&pid=1.9&rs=0&p=0&r=0.jpg

    no, that isn't the definition
    did you know the word LASER is an acronym ? ... that is, each letter stands for something

    Light Amplification by the Stimulated Emission of Radiation .... the radiation in this case being IR or visible light

    google " what is a laser?" and see what you come up with
    then come back with any question on things you read and didn't understand :smile:

    we are here to help you learn

    cheers
    Dave
     
  16. May 18, 2016 #15

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    They did not magnify it. They just used a large fire.
    A laser works completely differently from all the other light sources discussed here. You cannot use the light of any of them to "make a laser". You have to start completely differently if you want to actually make a laser.
    Start by reading what a laser is.
    The phone might be able to detect strong infrared light, and probably display it as red.
     
  17. May 18, 2016 #16

    russ_watters

    User Avatar

    Staff: Mentor

    I ignored it because "laser" was in quotes, which implied to me that the OP knew that what would be created wouldn't really be a laser. Unfortunately, I was not correct...
     
  18. May 18, 2016 #17

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    There is a lot of confusion and changing of direction in this thread (the most absurd of which is probably that you need a 4.04 GPA to get to Harvard) but the original question has an answer: the absolute best you can do is to have an image on the paper that is the same size and temperature as the filament of the light bulb. That is probably not enough to ignite a sheet of paper.
     
    Last edited: May 19, 2016
  19. May 19, 2016 #18

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    That's quite a challenge and nothing in your original post would count as making a laser.

    Youtube has a series on making a DIY C02 laser...

    and a ruby laser..


    Note it would be dangerous to build and operate one of these without taking appropriate safety precautions.

    Edit: At one point in the follow up video he states that the peak power going into his pulsed ruby laser is 4 Mega Watts supplied by a bank of capacitors charged to 6-8kV. Perhaps there are easier ways to improve your grades :-)
     
    Last edited: May 19, 2016
  20. May 19, 2016 #19

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Especially for (but not limited to) the CO2 laser, as you don't see the infrared beam easily.
    Electrical dangers are there for both.
     
  21. May 19, 2016 #20
    Thank you all, I talked to my science teacher, and he agreed with me that this is too hard, and because I was the one to bring it to his attention, I still got the extra credit. (that doesn't mean I won't try to make one still)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Is it possible to magnify light heat?
  1. Light and heat? (Replies: 4)

Loading...