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Thread: hello

  1. #1
    OptiBoard Novice
    Join Date
    Jan 2019
    London, United kingdom
    Dispensing Optician

    Exclamation hello

    hello..... i have a student who is doing the DO course and I had graduated DO course about 10 years ago. I have forgotten all the formulas. Not sure how to explain or show the student.

    Here is the questions:

    1. What is the sag of this surface over a diameter of 60mm?
    2. A pencil of light is made to converge to a point 20cm beyond a lens. Find the curvature of the wavefront:

    a) on leaving the lens
    b) 1cm from the lens,
    c) 19.9cm from the lens
    d) 21cm from the lens.

    some guidance and help would be great.

    Thank you.

  2. #2
    Master OptiBoarder OptiBoard Silver Supporter rdcoach5's Avatar
    Join Date
    Dec 2006
    Rossford, Ohio
    Dispensing Optician

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