Hacker News Reader

A mirror reflects with specular reflection. When parallel rays of light hit a flat mirror they remain parallel after being reflected:

https://en.wikipedia.org/wiki/Specular_reflection

Paint reflects primarily with diffuse reflection. The rays of light are scattered in all directions:

https://en.wikipedia.org/wiki/Diffuse_reflection

View on HN

That's an awesome learning point; thank you.

What percent of the light does a mirror reflect in a specular way?

Like the design of paint, the design of a mirror can affect its reflectivity. For an extreme example:

https://www.semrock.com/maxmirrors.aspx

Mirrors that are a cheaper coating on glass or metal can be in the 95% range without too much effort. If you don't care about actually forming an image with a mirror, it can be quite cheap, e.g., plain aluminum (with whatever oxide forms on its surface) or aluminized mylar film.

I was going to ask this same question, thinking it would be a dumb question, glad this got answered! Thank you

Reply on news.ycombinator.com