Originally Posted by
marcuslucas
Hi everyone,
I'm new to the thread but have found it to be an invaluable learning resource thus far. I was hoping to get some insight into
an exam question example.
A -4.00D lens is made in glass of refractive index 1.53 with a +5.00D base curve and edged to a 46x40 oval shape. The thin-edge substance of the lens is 3.0mm. what is the thick-edge substance?
What I've done so far is to calculate the the front radius as 106mm and the back surface radius as 58.88m, from front surface +5.00D and back surface -9.00D . Then using the exact sag formula I have calculated four sag values; two in the horizontal meridian a diameter of 23mm and two in the vertical meridian of 20mm
s1 = 2.52mm , s2= 4.67mm ,s3 = 1.09mm , s4 = 3.50mm. This is the part i'm having trouble with I don't know how to proceed from here any help or suggestions would be greatly appreciated.
Thanks in advance.
Bookmarks