\(power \ of \ a \ lens \ (D) = \frac{1}{focal \ length \ (m)}\) A lens has a power of -3.33 dioptres. Calculate the focal length and state what type of lens it is.

[Dusjagr] has another take on building a laser projection microscope. Last year we saw ... led [Dusjagr] to the discovery that a lens re-purposed from a webcam can achieve similar focus results ...