How Do Infrared Goggles Work?

What Are Humans Lacking?

Why is it that humans cannot see in the dark and need assistance from infrared goggles? Humans are missing a layer of the eye that other vertebrates have. This missing piece is a layer of tissue called the tapetum lucidum. This tissue can be found behind the retina, and in some animals, in the retina. It works by reflecting light back into and through the retina. This increases the amount of light that photoreceptors have to work with and improves vision in conditions that are low in light. A comparable process is that of thin-film optics where the reflective iridescent properties are available due to the thinness of wavelengths of light, usually around 500 nanometers thin. The tapetum lucidum is different in that it uses a reflective white hue, instead of iridescence, that is the result of a more organized crystal quality that reduces diffraction.

Infrared Goggle Results

Infrared goggles are used to see in the dark, an ability that humans have on a very limited basis. Infrared goggles work by utilizing the light spectrum, allowing the infrared portion of the spectrum to be converted so that the human eye can see it.

There are many ways for the human eye to see infrared light but generally two methods are the easiest to use for results with night vision infrared goggles. One is image enhancement and the other is the process of thermal imaging. Image enhancement works by finding the infrared light that the eye cannot see and amplifying the light until we can see it. Thermal imaging grabs the higher level of infrared light, which emits as heat, and reveals it to the eye. In thermal imaging, a warm body glows and colder objects like buildings or cars emit less light.

Using Infrared Goggles

By cutting out levels of the light spectrum and enhancing those that are in the infrared portion, the human eye can see at night. A series of discs, or lenses, are used in the goggles to allow the eye to see differently. The drawbacks with many infrared goggles are a distinct inability to perceive depth and a tendency toward a fuzzy image. Products can vary in their magnification, resolution, and viewing range. The price tag can be a general indicator of an advanced technology being used and therefore the possibility of a clearer image. Goggles with a binocular ability usually allow for further vision capability. Intense light should not be viewed with infrared goggles.