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Solid state lasers (LEDs), gas lasers, and liquid lasers(?)

  1. Jan 7, 2005 #1
    I've been doing a ton of research recently on how lasers work.

    Basically a laser is actually L.A.S.E.R which stands for "Light Amplified of Stimulated emitted radiation".

    A laser is cohernet, which means it is only its wavelengths are not fixed.

    Low power red lasers are often known as LED's. "Light emitting diode" or, "laser emitting diode", either way.

    Laser light is a special kind of light. Again, it only exists in one color, where normal light is diffusive and non concentrated, which includes a whole spectrum of colors.

    Since buying lasers above the 5 mW range is illegal, I've decided I am going to try and make my own. This is dangerous, considering I do not have a degree in optics. So if anyone knows anymore information on laser optics I can find let me know please.

    I've already got a plan on how to make my own laser, but for that I'd first need a laser power meter (in order to not overheat it) I'm going to make a laser from the gas argon.

    I must find a glassblower who is willing to make a florescent glass tube in which flourescent light will flow in the exact dimensions that I give; as well as having access to special laser curcuits to staunch the enormous energy power.

    Here's a list of things I've dicided I need to do to make one, please add if you feel its nessicary:
    1) Pure argon. (For the lasing medium.)
    2) A flourescent tube (I could probably find one in working condition in a old camera)
    3) A transformer.
    4) Special curcuits to handle the energy.
    5) Optical fibers.
    6) Battery.

    Please note *that I want to make a laser as crude as possible, I do not wish to sell it and only intend to use it in my house for personal experiments.*

    Thank you.
  2. jcsd
  3. Jan 7, 2005 #2
    forget it, you don't even know what laser is.
    laser has only single wavelength...
    led does not emit laser....
  4. Jan 8, 2005 #3
    This is not correct. You have several types of coherency like time and space coherency. Generally coherent means that for example two waves will keep on exhibiting constant bahaviour as they pass trhough space and as time passes on. For example if you were to look at two distinct points on each wave, each separated by a distinct distance, these points will remain at that same distance thourghout the entire motion of the wave. This means that one of the constituent sub-waves will not run away from the other sub-wave...The keep moving along as one fixed entity. Therefore you can build one resulting total wave out of several sub-waves, and this total wave will not scatter of in many directions as it moves on. It remains one wave that propagates in one direction. Basically coherent waves are very ordened while incoherent waves are chaotic in nature...

    Check out my journal for more info on this aspect of quantum electronics. Just look at the quantumelectronics and photonics entry...

    When constructing a laser you biggest problem will be the construction of the right resonator that will give rise to the wanted energies. You need to calculate the distance between the reflecting mirrors, the curvature of the mirrors and you will need to check your system for stability. You know, the socalled g-coefficients.

  5. Jan 8, 2005 #4


    leds can be constructed using the principle of semiconductor lasers, so YES they emit laser light

    Last edited: Jan 8, 2005
  6. Jan 8, 2005 #5
  7. Jan 8, 2005 #6
    Some LED's emit laser light (CD players and pointers), some don't (digital alarm clock).

    It depends on the specifics of their construction, but in both cases, light emission is based on the same process of electron-hole recombination in doped semiconductors.

    As for building an argon laser, it will be a time-consuming and expensive project. I recommend you learn everything you can before investing. Unless you are settled down or perhaps retired, you don't seem ready to seriously consider this.
    Last edited by a moderator: Jan 8, 2005
  8. Jan 8, 2005 #7
    Yes, you are absolutely right. I actually should have said I'm thinking of creating one, not doing so this second , since I must pratice alot more in calculus to construct the formulas for the curvature of the circle, and the distance between the two circles. (One circle is reflective, the other half slivered)

    And I will read the links you guys gave me.

    Thank you.

    PS: What is a g coefficent? I know that 1g is the force of gravity (9.8m/s), and a coefifcent is the number before g, so that would be N(g) where N is the coeffiecent and that equals the force of gravity. This is a very simplified view..but it is just my estimation of what you suggested.

    Are there any essays or papers i can read that are not too technical? For example, they explain what the the 'technical' stuff is.
  9. Jan 8, 2005 #8


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    I know what the A- and B- coefficients for a laser are (due to Einstein), but can't recall hearing of a g-coefficient.

    I'm guessing that marlon is refering to the gain coefficient, [itex]\gamma [/tex] appearing in a Beer-Lambert form of relation [itex] E_{out} = E_{in} e^{\gamma l} [/itex]
  10. Jan 8, 2005 #9
    QuantumTheory: Here is a site you might find useful http://repairfaq.ece.drexel.edu/sam/laserfaq.htm#faqtoc

    I myself plan on doing some holography, so I'm considering buying an old surplus HeNe gas laser for it. I don't have the time to build my own laser though.

    Good luck with it, hope that site is useful.
  11. Jan 9, 2005 #10
    I realise that before I even contemplate about actualy building a laser, I must learn alot more. Before I actually BUY one, I must learn alot more about optics and physics with lasers before I experiment with holography.

    When I turn 18 I plan in getting a degree in physics as well as optics (Isn't optics science "built in" the degree of physics?)

    My question to you is: When I do have the appropriate degree, how do I manage to buy one without violating the law? I plan to work for NASA, since I cannot join the militray due to a mental condition (depression).

    My father has worked there.My grandpa (a physist) has worked there in the past. My mom has worked there for a short period of time.
  12. Jan 9, 2005 #11

    Look, why do you want to make or buy a laser...This is entirely useless man. What is your goal ??? If you wanna learn about this go study physics and specialize in optics, photonics and quantum-electronics. Check my journal for some nice online courses concerning these topics...

  13. Jan 9, 2005 #12
    Besides laser pointers, no one can possibly have a reason for wanting a laser at home, much less an illegal one. An average laser lab costs more than a house, and they have security measures which you will learn from your professors, such as no jewelry or reflecting surfaces in the room, goggles, no bending over, locked doors, etc, etc. Many lasers also have to work in very clean environments so specs of dust don't burn on expensive laser lenses and mirrors.

    Get a laser pointer for your current itch, then when you have done your Bachelor's, have your Master's degree be building whatever kind of laser you want from scratch. If you have no experience yourself, you need a supervisor.
  14. Jan 18, 2005 #13
    Home Built Lasers

    -There are no laws regarding possession of lasers.

    -A diode laser is not the same as a light-emitting diode (LED), though they are related.

    -You could construct a low-power He-Ne laser fairly easily if you could fabricate and fill a discharge tube with He and Ne at the right partial pressures. The laser mirrors would have to be purchased to be of adequate quality, but they are inexpensive (~$20-50). There are many books, and internet sites, on the details of home-built lasers.

    -If you are interested in lasers, I suggest the book "Lasers" by Anthony Siegman.

  15. Jan 18, 2005 #14

    Claude Bile

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    QuantumTheory, you are way out of your depth. Save your enthusiasm for university.

    P.S. The g coefficient is used in two main contexts in laser physics. The first is related to degeneracies in the energy levels of the laser. The second (which I believe is what marlon was referring to) refers to the stability of a laser cavity. G is just a convenient parameter to define whether or not a given cavity is stable or not.

  16. Jan 19, 2005 #15
    You are completely correct...

  17. Jan 30, 2005 #16
  18. Nov 29, 2005 #17
    There are many uses for higher powered lasers for personal use. I know of several high powered cutting lasers that are in people's garages. One cuts precision parts out of hard tool steel for making other machines. The benifit of the laser cut hard steel is that the surface is hardened more during the cutting and shaping and therefore increases the useful life of the part.

    Another is used with a CNC machine for cutting and engraving ultra-hard and delicate materials for both artistic and usable projects. The guy likes to demonstrate his laser CNC machine by engraving complex carvings on egg shells which many people have purchased for as high as $500.00 apiece.

    Another is used by an artist for many of her projects which includes shaping parts and engraving textures, plus, computer generated portraits burned into the center of Lexan blocks. Her lower power laser is used to scan 3D objects into her computer as 3D STL files for manipulation and eventually to be laser shaped in to metal or some other substrate.
    Another is used by a electonics hobbiest to make the traces and the holes in PCB boards. He belongs to several clubs and supplies the PCB boards to the other members. It used to take several hours to make a PCB board using either photo methods or cutting with a CNC machine. Now, he can make 20 to 30 in an hour depending on the size.

    Another laser is used to engrave on jewelery..

    Another guy is experimenting with a three lasers connected together by a computer, emitting three colors to paint moving pictures suspended in space. He has had some success with still pictures at this time.

    The reason that I even post is that it always bothers me somewhat when people make statements that "someone couldn't possibly have a reason to......... [whatever]" I remember when IBM said the same thing about the personal computer. I remember reading about how a group tried to stop the Wright Brothers because the group believed that the Wright Brothers couldn't possibly have a reason to try and fly... In the late 1800s, the then head of the patent office stated that the office should be closed because all that could be invented or discovered had already been done..

    This is extremely short sighted on the part of people who feel that one should not do anything on a personal level because they, themselves, can not see any use for a given item. This type of thinking not only squashes progress, but tampers with the freedom and imagination of others. There are many people that are limited to think within a box and beleive that others should be held by the same constraints..
    Last edited: Nov 29, 2005
  19. Nov 30, 2005 #18
    No Marlon! It's true that cd-rom readers are based on semiconductor lasers! They look like LED... But generally you don't refer to a laser when you talk about a led... The most common LED is on your TV remote control!
    If it emits laser light I am Cleopatra!
  20. Nov 30, 2005 #19
  21. Dec 1, 2005 #20

    You did not read my post thoroughly. I never said that all LED's emit laser light.

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