Microwave photons and microwave oven doors

[The Photon]

A microwave photon can not pass through a microwave mesh. If photons are point-like particles, I am confused how a photon of certain frequencies can not pass through a hole that is of significant size. When a photon of the same frequency or a photon from a radio station for example is absorbed by a material it does not excite a large group of molecules, it gets localized, hence the confusion.

[swansont]

Size of a photon is somewhat nebulous. It interacts electromagnetically, which has a spatial extent. When passing through a hole in a conductor, it may interact strongly if the hole is smaller than the wavelength - one has to look at the diameter and length of the opening. So you can filter out wavelengths above some threshold, with high efficiency, depending on the geometry of the hole.

Microwave oven photons are several cm in wavelength, and the mesh holes are much smaller.

[Sensei]

I created microwave mesh in 3D application:

 

It allowed for easy calculation of area of holes. It's 1/3. i.e. 33% of visible photons pass through and 66% of visible photons are reflected by metal (if there would be no glass). I suppose so manufacturers of glass used in microwaves additionally also use some metal admixture without significantly decreasing visibility. Metals are good microwave reflectors.

[swansont]

3 minutes ago, Sensei said:

Metals are good microwave reflectors.

The reflectivity of your mesh would be about 100%, because its wavelength is larger than the transmission cutoff, while for optical, the wavelengths are far below. Thus the reflectivity for optical in this case is dictated by the surface area vs hole area, and for RF/microwave it is not.