Page 1 of 8 12345 ... LastLast
Results 1 to 10 of 73

Thread: Blue laser 445nm

  1. #1
    Join Date
    Mar 2007
    Location
    Rotorua New Zealand
    Posts
    528

    Default Blue laser 445nm

    Hi all,

    I have been looking at upgrading my red what with Marconi not being around right now and I need to have a red with the RGB (my Maxxy is still going fine..but what if !!)

    Of course this leads to the fact that blue is also an issue of I go say 1 watt red at 640nm..

    So I have been looking at most of the manufacturers of 640 reds the nice ones are European that I can find. The Chinese so far do not produce these.
    I also asked about blue..

    Here is what Arctos had to say and I don't think I have seen this talked about here on PL (I may have missed it of course) but it may explain why many of these companies offer 445nm..

    Arctos say :

    Max sensitivity of the human eye for blue is 445nm- please convince yourself by googling this... it is highly interesting.
    The longer blue wavelength the more stimulated are your green receptors in your eye, so more laser power is necessary. Even if 457nm pure blue seems brighter as 445nm ! BUT.Its a mystery and a fact..

    end quote..


    Just food for thought be interested to see what some of you opto and medical guys think about this..
    Its not in dispute by me just an interesting point I guess..

    Cheers

    Ray

  2. #2
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
    Posts
    799

    Default

    In my voyage into color science I have stumbled upon the same phenomenon. There is no doubt that longer wavelengths blue appear brighter (higher luminous efficiency) than 445nm light, but despite this fact you actually need less 445nm than 473nm to make a good white balance.

    The problem is that the 445 by itself will look rather weak. For example, this combination has a decent white (#eeeaff in html; slightly blue):
    550mW 532nm
    1W 640nm
    400mW 445nm

    Comparing these lasers side by side the red and green would be far stronger, but according to the color matching functions (I'm using Judd-Vos now) you only need so little 445 to make white.

    So how does one get a powerful blue with 445 without messing up the white balance?

  3. #3
    Join Date
    Dec 2006
    Location
    Netherlands
    Posts
    964

    Default

    Quote Originally Posted by Pitts View Post
    Arctos say :

    Max sensitivity of the human eye for blue is 445nm- please convince yourself by googling this... it is highly interesting.
    The longer blue wavelength the more stimulated are your green receptors in your eye, so more laser power is necessary. Even if 457nm pure blue seems brighter as 445nm ! BUT.Its a mystery and a fact..

    end quote..


    Just food for thought be interested to see what some of you opto and medical guys think about this..
    Its not in dispute by me just an interesting point I guess..

    Cheers

    Ray
    Hi Ray,

    thanks for sharing that! I'm not medical or opto (by training) but like share what I'm thinking. Google finds many different graphs out there that show how the human eye responds to light and I haven't taken the time to understand exactly why, and the one below probably is not the best but these are my thoughts:

    What Arctos says has to do with the overlap of the blue and green curve and achieving white balance. If you add more 473nm to the mix you actually add the same amount of blue as green. The extra green throws off the mix, which in turn requires more blue again to get the mix right (and more red probably).
    If you add 445nm to the mix, the blue only appears less bright (according to the overall luminosity curve) but the blue response of the eye is much bigger - so you need less of it to get the white balance right.

    The difference is in the stand alone brightness of blue and amount of blue needed for achieving white. 473nm will get you brighter beams for the mW and 445 will get you better white balance for the mW. Guess you need both in the projector



  4. #4
    Join Date
    Jan 2007
    Location
    Yorkshire, UK
    Posts
    4,585

    Default

    Hi Ray

    I was going to try and explain this myself. However, there's a link that explains it much better than I ever could here...

    http://hyperphysics.phy-astr.gsu.edu...n/rodcone.html

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  5. #5
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
    Posts
    799

    Default

    I'm currently reading a book called "The science of color". It explains all this fairly deeply. I recommend it for anyone interested in the topic. Some knowledge of maths may be required to process it though.

    http://www.amazon.com/Science-Color-...369444&sr=11-1

    By the way, Jem, that hyperphysics page has a serious shortcoming when it comes to color mixing. I ended up with a completely absurd setup using the equations there.

  6. #6
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,073

    Cool

    On the recent ILDA cruise, I had the chance to see the output from the Infinity series projectors thad Dirk Bauer brought. They have the 445 nm diodes in them for blue.

    I must admit that at first, I was quite impressed with the very deep blue line. However, after a while I realized that I missed the brighter 473 nm line.

    In the end, I decided that I actually prefered the 473 nm blue to the 445 nm blue. Of course, this is a matter of personal preference, but to me, the 445 nm blue was too close to violet to be called "blue".

    I think Zoof has the perfect solution. Put *both* in your projector!

    Adam

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

    Wink

    Quote Originally Posted by buffo View Post
    I think Zoof has the perfect solution. Put *both* in your projector!
    And before we start the group buy for that "dichro", we can add the 445 and the 473, if properly polarized, with a PBS, correct?
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  8. #8
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,073

    Cool

    Correct - if both are polarized you can use a PBS cube and forgo the custom dichro. Might loose a few percent because of the difference in wavelengths, but it won't be a huge issue.

    Adam

  9. #9
    Join Date
    Apr 2008
    Location
    Amsterdam, NL
    Posts
    2,098

    Default

    Group buy for 445nm Diodes!!!

    How much are 445 diodes?

    Here is a link of a 50mW single mode 440nm doide: http://www.nichia.com/specification/ld/NDHB510APA-E.pdf

    They also have 500mW multimode diodes http://www.nichia.com/specification/ld/NDB7112E-E.pdf

  10. #10
    Join Date
    Jan 2007
    Location
    Yorkshire, UK
    Posts
    4,585

    Default

    Quote Originally Posted by tocket View Post
    ... I ended up with a completely absurd setup using the equations there.
    I don't do equations
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

Posting Permissions

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