Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Using lenses what determines focal point?

Joined
Sep 2, 2007
Messages
251
Points
0
Ok, so in anticipation of my laser arriving i've been destroying binoculars and cameras and stuff to get the lenses.

So far i have made two lens caps both using plano convex lenses.

Using a cheap 1mw red laser i decided to test the focal points the first one has a focal point of about 1cm from the lense and the other one has a focal point of about 8cm from the lense.

What determines where the focal point is?
Is it to do with the curvature of the convex side of the lense or what?

Thanks
Rich
 





Joined
Jul 20, 2007
Messages
220
Points
0
randomer3 said:
Is it to do with the curvature of the convex side of the lense or what?
Directly, the curve determines the way light takes, and where it makes the focal point, not a very scientific way of explaining it but i hope you understand :D
 
Joined
Sep 2, 2007
Messages
251
Points
0
I think i do, so the smaller/shallower the curve the further the focal point would be...?
 
Joined
Jul 20, 2007
Messages
220
Points
0
Randomer3 said:
I think i do, so the smaller/shallower the curve the further the focal point would be...?
I think so, not 100% sure, i know that is true for mirrors where it curves inside..
 
Joined
Aug 15, 2007
Messages
1,880
Points
0
paper183 is correct. The shallower the lens, the further the focal point. You can go into using multiple lenses and adjusting them (like the Aixiz modules) but I don't know so much on that.
 




Top