What can pass through glass?

Transmission of Various Wavelengths Through Glass

Glass, a versatile material primarily made from silica, is known for its transparency and ability to transmit light. However, the spectrum of electromagnetic radiation that can pass through glass varies significantly depending on the type and thickness of the glass. Here, we delve into the details of what can and cannot pass through glass.

Visible Light

Visible light, which ranges from approximately 380 to 750 nanometers in wavelength, can readily pass through most types of clear glass. This property makes glass ideal for applications requiring illumination or visibility, such as windows and eyeglasses. The transparency to visible light is what gives glass its unique utility in countless optical applications.

Infrared Rays

Infrared (IR) radiation, which lies beyond the red end of the visible light spectrum, experiences varying degrees of transmission through glass. Short-wave infrared rays (up to about 3000 nanometers) can partially pass through glass, but as the wavelength increases, glass increasingly absorbs and blocks IR radiation. Special types of glass, such as borosilicate or quartz, can transmit IR to a greater extent than standard soda-lime glass.

Ultraviolet Rays

Ultraviolet (UV) rays, which are found on the opposite side of the visible spectrum from IR, are largely blocked by ordinary glass. While a small amount of UV radiation (especially long-wave UVA around 320-400 nm) can pass through glass, most UV radiation is absorbed. Special UV-transmitting glasses are required for applications needing UV transmission.

Radio Waves and Others

Longer wavelengths, such as radio waves, microwave radiation, and even longer terahertz waves, can pass through glass with varying effectiveness. The transmission depends on the glass composition as well as the wavelength and frequency of the waves.

In sum, glass's ability to transmit electromagnetic radiation varies widely across the spectrum, making it a diverse and invaluable material in both everyday and specialized applications.