My Favourite Polariser Trick

Discussion in 'Beyond the Basics' started by Garbz, Feb 12, 2009.

  1. Garbz

    Garbz No longer a newbie, moving up!

    Joined:
    Oct 26, 2003
    Messages:
    9,713
    Likes Received:
    203
    Location:
    Brisbane, Australia
    Can others edit my Photos:
    Photos NOT OK to edit
    Ok so not really photography, but here's a little physics phenomenon for you, posted here because well we all have these filters at home to play with.

    Lets start with a poorly resized image of a computer monitor, and LCD, and something about LCDs is that they have a large linear polariser across their surface:

    [​IMG]

    So now to add our camera's linear to circular polariser and adjust the rotation angle so the screen's polariser and our polariser are 90 degrees out of phase:

    [​IMG]

    A few notes here: This could be an interesting backlighting project seeing how linear polarised light changes polarisation angle when it scatters off a surface creating the weird backlit effect off my calibrator, ... and all the dust on my screen.

    And now we add another polariser into the picture. This time a Linear to Circular Polariser, in phase with the screen's linear polariser. This means the light going through the polariser is not cut out, but rather returned to a circular polarisation. The camera polariser has no effect on the circular polarised light beyond it's own insertion loss.

    [​IMG]

    Volah if this doesn't get your kids interested in optical physics nothing will... I am serious... this is exactly why there are so few optical physicists in the world.
     
  2. jlykins

    jlykins TPF Noob!

    Joined:
    Dec 1, 2007
    Messages:
    1,235
    Likes Received:
    0
    Location:
    Cincinnati
    Can others edit my Photos:
    Photos OK to edit
    That's cool. I'm going to have to try that when I get home...
     
  3. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

    Joined:
    Aug 25, 2003
    Messages:
    7,021
    Likes Received:
    34
    Location:
    Lawrence, KS
    Can others edit my Photos:
    Photos NOT OK to edit
    Sometimes when I'm out in bright light I'll look to the LCDs on my camera, and it'll be very hard to see. I'll be like "What the!?!?", and then "Oh yeah, I'm wearing polarized sunglasses." :)
     
  4. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

    Joined:
    Dec 16, 2003
    Messages:
    33,822
    Likes Received:
    1,811
    Location:
    Edmonton
    Can others edit my Photos:
    Photos NOT OK to edit
    Happens to me ALL THE TIME! :lol:
     
  5. Judge Sharpe

    Judge Sharpe TPF Noob!

    Joined:
    Feb 13, 2008
    Messages:
    307
    Likes Received:
    0
    Location:
    birmingham alabama usa
    Can others edit my Photos:
    Photos OK to edit
    The one that Got me was when I was flying in a rental C-172, and the radio setting would not come a cross with Polarizing sunglasses on. I thought the rasio was dead.
    If you cross 2 linear polarixing filters, the closer they come to 90 degrees, the darker the light becomes untill allis blocked out. An adjustable ND filter. Many times privacy glass in windows has a ploarizing film on it and you can clear it by looking through a polarizing filter turned 90 degrees in its axis. Not that anyone would want to do that.
    JS
     

Share This Page