Determination of microlens focal length

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Discussion Overview

The discussion centers around determining the focal length of a microlens, specifically addressing the applicability of the lensmaker's equation in this context. Participants explore both theoretical and experimental approaches to measuring focal length.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks an equation to determine the focal length of a spherical microlens in a vacuum and questions the use of the lensmaker's equation.
  • Another participant suggests an experimental method involving collimated light or imaging a distant object to measure the focal length directly.
  • A participant expresses interest in the theoretical effective focal length and reiterates the question about the lensmaker's equation's applicability to microlenses.
  • There is a query about the potential for the microlens to be aspherical, which may affect the use of the lensmaker's equation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the lensmaker's equation is suitable for microlenses, indicating a lack of agreement on this point. Multiple viewpoints regarding theoretical and experimental approaches are presented.

Contextual Notes

The discussion does not clarify assumptions regarding the shape of the microlens or the specific conditions under which the lensmaker's equation might apply, leaving these aspects unresolved.

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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