Page 3 of 8 FirstFirst 1234567 ... LastLast
Results 21 to 30 of 71

Thread: Pioneer 112 Results (red Hot)

  1. #21
    Join Date
    Sep 2007
    Location
    ,essex, uk
    Posts
    166

    Default

    cool thanks Rob i must have one in the scrap parts from all the burners iv taken apart what does this thing look like i know that sound strange but iv never taken that much intrest in most of the other optics apart from the cubes if that makes sence lol

  2. #22
    Join Date
    Jan 2007
    Location
    Sheepsville, Wales, UK
    Posts
    3,406

    Default

    sometimes they are mounted in a nice plastic surround of about 6 or 7 mm diameter but often are just a slip of glass a few mm square on the end of the diode housing - they will always be in close proximity to the diode output. If you look through one at a light you will see rainbow colours - thats your grating

    Rob
    If you need to ask the question 'whats so good about a laser' - you won't understand the answer.
    -----------------------------------------------------------------------------------------------
    Laserists do it by the nanometre.

    Stanwax Laser is a Corporate Member of Ilda

    Stanwax Laser main distributor of First Contact in UK - like us on Facebook http://www.facebook.com/FirstContactPolymerCleaner
    www.photoniccleaning.co.uk

  3. #23
    Join Date
    Sep 2007
    Location
    ,essex, uk
    Posts
    166

    Default

    nice one, ok ill give it a shot sould be intresting iv never tried this but i will give it a go ill try and put some pics with it

  4. #24
    Join Date
    Dec 2006
    Location
    Netherlands
    Posts
    983

    Default

    the gratings I've been using are from a simple cd-rom drive and one from a very very old hard disk drive that had an optical sensor to control head positioning. I've never looked through one (I'll try) but putting it in a laserbeam's path will give you a lot of dots on the wall. The middle dot is the brightest and is called the 0th order image. Then going outwards you get the 1st, 2nd, ... nth order images that should all appear less bright than the previous one.

    First step is to use the formula with a known wavelength (e.g. 532 ) to work out the grating spacing 'd' for the grating your recovered from the optics. Second step would be to check if you can accurately measure another known wavelength (e.g, 473 or HeNe) and get an idea of the accuracy. Third step is to measure the actual diode's wavelength.
    Having a large distance between grating and screen will help improve accuracy, and the screen should be placed at rightangles to the initial beam path (0th order image, or brightest spot)

    We know how 650nm is quite a bit brighter than 660nm, and that cooling diodes shortens wavelength. So there is a point to all this and measuring wavelength can be done easily. If people are interested I could write a step by step guide on how to do this with an excell sheet (next week I should have some time)

  5. #25
    Join Date
    Sep 2007
    Location
    ,essex, uk
    Posts
    166

    Default

    Thats cool Zoof i think there would be quite a few people intrested go for it when you have the time
    Paul

  6. #26
    Join Date
    Sep 2007
    Location
    ,essex, uk
    Posts
    166

    Default

    Well I had a go with the diffraction grating from an old burner, image one shows the first set up with an aixim module with a 658nm rohm diode which was a good reference point to start as the wavelength is known, I took the measurement from the brightest spot in the middle to the one on the left and right of it as accurately to 1 meter (1000mm) distance, I took the measurement, I then went and put a helium neon laser on as in pic 3 I could not get a noticeable difference in the measurement if there was one it was very small, I then put a 405nm niche (ps3 diode) on to test as it is on the other end of the visible spectrum I thought it would be a bit easier to see and I was right pic 4 but the main test was for the pioneer wavelength so I altered the set up to fire a bit further away as to get me a better separation from the He Ne /rohm /niche and pioneer the results were much better and are as follows.
    At 2770 mm the measurements went like this
    Rohm 69.5mm
    Pioneer112 68.5mm pic 7
    He Ne 66.3 mm pic 6
    Niche (ps3) 42.7mm pic 5
    I took the measurements from middle of spot to middle of spot and took the measurements as accurately as possible using a digital vernier but trying to follow the guide on how to obtain the wavelength I got lost and I am not sure with this information on how to work it out can someone help
    All the best Paul













  7. #27
    Join Date
    Oct 2006
    Location
    Cleveland, Ohio
    Posts
    2,342

    Default

    Assuming the diffraction distance is linear with respect to wavelength, and using the 405nm and 635nm lasers as a reference, the Rohm is operating at 666nm and the 112d at 656nm with a factor of 9.746nm/mm.

    At least we can say the pioneer is operating at a significantly shorter wavelength that the Rohm, which is good!

  8. #28
    Join Date
    Oct 2006
    Location
    Central Florida
    Posts
    7,067

    Question

    Um, I don't reply to these much cause I read and learn a little but am very ignorant and have nothing to add. You seem very good at this and I applaud your efforts. I just want to ask what are you measuring in you previous post? Divergence? You went though a lot of work, and I'd like to understand.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  9. #29
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Smile

    Aaron;

    He's using a diffraction grating to estimate the wavelength of the different lasers. He's got a few known wavelengths (the Hene, for example, and the Blue-ray, as well as the 658 nm Rolm - though I wouldn't take that one to the bank without checking it myself). So, assuming that the refraction index of the grating is linear across all wavelengths, he can measure the separation of the dots on the wall and thus calibrate his setup so he can measure any wavelength.

    Basically it's like sending the laser through a prism. (OK, slightly different because a prism refracts, while a grating will diffract, but the end result is the same - the beam bends a little or a lot depending on it's wavelength.)

    Ever notice how white light gets separated into a rainbow by a prism? That's because the red waves bend less than the blue ones. So the different wavelengths spread out. The farther away from the prism you are, the wider the separation between blue and red. Same thing for a diffraction grating, except that you get multiple copies of the beam.

    Thus, you can use this principle to measure the wavelength of an unknown laser, assuming you can measure the separation accurately enough, and assuming you have at least two known standards (such as a Hene and a single line argon, or even a dpss green) to calibrate your measurements with.

    You first measure the horizontal difference between the refracted (or diffracted) spots of your two standard lasers. Now divide the distance between the two spots by the difference in frequency of the two lasers. Presto! You just found a millimeter-per-nanometer constant that you can now use to measure the wavelength of *any* visible laser.

    Naturally, the aperture of the test laser must be at precisely the same position as it was for the two known standard lasers you used to calibrate with, and both the wall and the grating (or prism) must be in exactly the same position as well. But beyond that, it's a quick and dirty way to get a wavelength measurement. You can set something like this up in your house in about 5 minutes. (I would suggest you use a HeNe laser and a 532 nm pointer to calibrate, since the wavelengths of each laser are well known and will not change appreciably with changes in input power or ambient temperature. A 473 nm DPSS laser would give you a more accurate calibration, because your measured area will be wider.)

    The further away from the grating (or prism) the measurement is taken, the more accurate the result. Note too, that once you arrive at your constant, you can measure wavelengths above or below your calibration points as well, so long as the spot is still visible. The only assumption is that the diffraction response of the grating is linear for all visible wavelengths, which is a reasonable assumption.

    Adam
    Last edited by buffo; 02-03-2008 at 12:39.

  10. #30
    Join Date
    Oct 2006
    Location
    Central Florida
    Posts
    7,067

    Lightbulb

    So, take the RGB out of the grating in my signature. You can tell what wavelength each color is using the distance they are apart... Neat.

    And Paul, you are looking to see what wavelength lasers came with the ps3 tray? Was there an IR one also?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •