Very concise, handy and useful, both the functionality and the article.

Excellent instruction

Very useful for MM fiber coupling or PIN detector coupling

A helppful article. However, you did not address the effect of spherical aberration which is large for the lens you use. The lens should be either aspheric or a microscope lens. Also, you did not mention the match of the numercal aperture of the lens to the fiber NA. Modifying the fiber coupling example in zemax\samplesnon-sequential\fibers shows that reducing the input lens NA by 1% reduces the coupling efficiency into the fiber from 99% to 73%. Increasing the spot size from 2/3 the fiber diameter to 100% of the fiber diameter decreases it to 45%, the typical value the most neophyte fiber users get.