Microwave doors block radiation using a metal mesh with holes smaller than the wavelength of microwaves, but larger than visible light waves.
The metal mesh in a microwave door acts as a Faraday cage for microwave radiation. Microwaves have a relatively long wavelength, typically around 12 cm. The holes in the mesh are significantly smaller than this wavelength, preventing the microwaves from passing through and escaping the oven. However, visible light has a much shorter wavelength, on the order of nanometers, allowing it to easily pass through the same holes, which is why you can see inside the microwave.
While microwave doors are designed to contain radiation, it's always wise to ensure your appliance is in good condition and not damaged.
How is the microwave metal grid manufactured?
The microwave metal grid is typically manufactured using precision techniques like stamping or laser cutting. A sheet of conductive metal, such as aluminum or stainless steel, is precisely cut or pressed to create the pattern of small, uniform holes. The exact size and spacing of these holes are critical for effective microwave containment and are determined by the specific microwave frequency the oven uses. The resulting perforated sheet is then often laminated or integrated into the glass door assembly to ensure durability and safety.