Determination of microlens focal length

[milasiju]

Hi guys! I face some difficulty in finding the focal length of a microlens. Assuming that the microlens is spherical, and the medium of the surrounding is vacuum. I really need an equation to get me going for my research task. I actually found the lensmaker's equation which is
/=(−)(/−/+(−)/ ). I am not sure should i use this equation for microlens?
Thanks guys!

 

[Andy Resnick]

The most straightforward method is to either shoot collimated light though the lens and measure the distance to the focal point, or use the lens to image a distant object (usually an overhead light is sufficiently far away) and measure how far the lens is from the image.

 

[milasiju]

Yeap Andy that one will be helful in terms of getting experimental result. But i would know more about the theoretical effective focal length. It would be very helpful if you could tell me if the lensmaker's equation can be used for microlens. Thanks

 

[milasiju]

The lensmaker's equation that i meant is

1/f = (n-1)(1/R₁ - 1/R₂ + (n-1)d/nR₁R₂)

 

[Andy Resnick]

I don't understand- why *wouldn't* you use the lensmaker equation for a microlens? Is it perhaps an asphere?