Determination of microlens focal length

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Determining the focal length of a microlens can be approached using the lensmaker's equation, which is applicable if the microlens is spherical and surrounded by vacuum. The equation provided is 1/f = (n-1)(1/R1 - 1/R2 + (n-1)d/nR1R2). For experimental validation, one can either direct collimated light through the lens to measure the focal point distance or use the lens to image a distant object. Theoretical understanding of effective focal length is also sought, particularly regarding the use of the lensmaker's equation for microlenses. Clarification is needed on whether the microlens might be aspherical, which could affect the applicability of the equation.
milasiju
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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!
 
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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.
 
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
 
The lensmaker's equation that i meant is

1/f = (n-1)(1/R1 - 1/R2 + (n-1)d/nR1R2)
 
I don't understand- why *wouldn't* you use the lensmaker equation for a microlens? Is it perhaps an asphere?
 
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