We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What Is an IR Light Source?

By Jeremy Laukkonen
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

An infrared (IR) light source is any object capable of emitting light with wavelengths between about 1 and 400 terahertz (THz). Many sources emit infrared light in addition to visible and ultraviolet light, though some are designed or modified to only release wavelengths that fall within the IR band. Most sources of white light can be modified into exclusively infrared light sources using optical filters, though an IR light emitting diode (LED) requires no such modifications. The other type of IR light source is thermal radiation, which is created by the thermal motion of matter. Infrared cameras that make use of thermography can use the differing intensity of these IR light sources to determine temperature.

Most conventional light sources emit both ultraviolet and infrared light in addition to visible light. Over half of the energy that reaches Earth from the sun is invisible infrared light, a little less than half is visible and a small amount of ultraviolet accounts for the remainder. Conventional light bulbs, flashlights and other sources of light typically reach into the infrared band as well. In order to turn this type of broad spectrum light into an IR light source, an optical filter can be used.

Optical filters are designed to only allow the transmission of certain wavelengths of light. A red optical filter will appear red to the naked eye, as it is designed to only allow the transmission of wavelengths between about 400 and 480 THz. These filters can use a number of different methods to affect the passage of light, such as either absorbing or reflecting the unwanted wavelengths. When a properly designed optical filter is applied to a flashlight or light bulb, it can result in a practical IR light source.

Another type of IR light source emits only infrared light without any modifications or filters. The infrared LEDs that are commonly used in remote controls are one example of this type of IR light source. There is no optical filter involved, and the surface of these LEDs appear colorless. When electricity is applied to this type of LED, it can emit invisible infrared light.

Every object that emits heat also emits light, and in the case of normal matter at room temperature that light typically falls within the infrared spectrum. This is the basis of thermography, which involves the photography of thermal images. These images can be displayed in false-color, which assigns darker hues to cooler areas and lighter colors to warmer areas. Thermography is sometimes used for night vision, though it is also possible to use an invisible IR light source to illuminate a dark area.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.