Lens Help?
Hello,
Thanks so much for reading this. I think I'm close I"m just not confidant in my answer. The problem reads: For a thin planoconvex lens, what is the change in focal length (Delta f) for a 100 um change in radius (delta R) of the convex surface. Assume the lens has a visiblewavelength refractive index of n=1.5.
I know 1/f=(n1)(1/R11/R2)
For the plano side the R1 is going to be infinite I think. Which gives me n and R1. Can I do the equation twice, once with R2=100 and once where R2=200, solve for f in each case, and then subtract the results? i.e.
• 1/f1=(n1)(1/R11/R2)
• 1/f1=(1.51)(1/Infinity1/100)
• f1=200
• 1/f2=(n1)(1/R11/R2)
• 1/f2=(1.51)(1/Infinity1/200)
• f2=400
• delta f = f1  f2
• delta f = 200
Thank you again for your feedback!
