Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light.It is therefore generally invisible to the human eye, although IR at wavelengths up to 1050 nanometers (nm)s from specially pulsed lasers can be seen by humans under certain conditions.
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Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms.
Infrared (IR) radiation is a type of electromagnetic radiation (a wave with electricity) . The wave is longer than light which humans can see and shorter than microwaves. The word infrared means below red. It comes from the Latin word infra (meaning below) and the English word red. (Infrared light has a frequency below the frequency of red ...
- Focusing Infrared
- Film Cameras
- Digital Cameras
In infrared photography, the film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about 900 nm. Film is usually sensitive to visible light too, so an infrared-passing filter is used; this lets infrared light pass through to the camera, but blocks all or most of the visible light spectrum. When t
Until the early 20th century, infrared photography was not possible because silver halide emulsions are not sensitive to longer wavelengths than that of blue light without the addition of a dye to act as a color sensitizer. The first infrared photographs to be published appeared in the February 1910 edition of The Century Magazine and in the October 1910 edition of the Royal Photographic Society Journal to illustrate papers by Robert W. Wood, who discovered the unusual effects that now bear his
Most manual focus 35 mm SLR and medium format SLR lenses have a red dot, line or diamond, often with a red "R" called the infrared index mark, that can be used to achieve proper infrared focus; many autofocus lenses no longer have this mark. When a single-lens reflex camera is fitted with a filter that is opaque to visible light, the reflex system becomes useless for both framing and focusing, one must compose the picture without the filter and then attach the filter. This requires the use of a
Many conventional cameras can be used for infrared photography, where infrared is taken to mean light of a wavelength only slightly longer than that of visible light. Photography of rather longer wavelengths is normally termed thermography and requires special equipment. With some patience and ingenuity, most film cameras can be used. However, some cameras of the 1990s that used 35mm film have infrared sprocket-hole sensors that can fog infrared film. Other film cameras are not completely opaque
Digital camera sensors are inherently sensitive to infrared light, which would interfere with the normal photography by confusing the autofocus calculations or softening the image, or oversaturating the red channel. Also, some clothing is transparent in the infrared, leading to unintended uses of video cameras. Thus, to improve image quality and protect privacy, many digital cameras employ infrared blockers. Depending on the subject matter, infrared photography may not be practical with these ca
Far infrared (FIR) is a region in the infrared spectrum of electromagnetic radiation.Far infrared is often defined as any radiation with a wavelength of 15 micrometers (μm) to 1 mm (corresponding to a range of about 20 THz to 300 GHz), which places far infrared radiation within the CIE IR-B and IR-C bands.
- Health effects
An infrared heater or heat lamp is a body with a higher temperature which transfers energy to a body with a lower temperature through electromagnetic radiation. Depending on the temperature of the emitting body, the wavelength of the peak of the infrared radiation ranges from 780 nm to 1 mm. No contact or medium between the two bodies is needed for the energy transfer. Infrared heaters can be operated in vacuum or atmosphere. One classification of infrared heaters is by the wavelength bands of i
German-British astronomer Sir William Herschel is credited with the discovery of infrared in 1800. He made an instrument called a spectrometer to measure the magnitude of radiant power at different wavelengths. This instrument was made from three pieces. The first was a prism to catch the sunlight and direct and disperse the colors down onto a table, the second was a small panel of cardboard with a slit wide enough for only a single color to pass through it and finally, three mercury-in-glass th
The most common filament material used for electrical infrared heaters is tungsten wire, which is coiled to provide more surface area. Low temperature alternatives for tungsten are carbon, or alloys of iron, chromium, and aluminum. While carbon filaments are more fickle to produce, they heat up much more quickly than a comparable medium-wave heater based on a FeCrAl filament. When light is undesirable or not necessary in a heater, ceramic infrared radiant heaters are the preferred choice. Contai
Infrared heaters are commonly used in infrared modules combining several heaters to achieve larger heated areas. Infrared heaters are usually classified by the wavelength they emit: Near infrared or short-wave infrared heaters operate at high filament temperatures above 1800 °C and when arranged in a field reach high power densities of some hundreds of kW/m2. Their peak wavelength is well below the absorption spectrum for water, making them unsuitable for many drying applications. They are well
In addition to the dangers of touching the hot bulb or element, high-intensity short-wave infrared radiation may cause indirect thermal burns when the skin is exposed for too long or the heater is positioned too close to the subject. Individuals exposed to large amounts of infrared radiation over an extended period of time may develop depigmentation of the iris and opacity of the aqueous humor, so exposure should be moderated.
Electrically-heated infrared heaters radiate up to 86% of their input as radiant energy. Nearly all the electrical energy input is converted into infrared radiant heat in the filament and directed onto the target by reflectors. Some heat energy is removed from the heating element by conduction or convection, which may be no loss at all for some designs where all of the electrical energy is desired in the heated space, or may be considered a loss, in situations where only the radiative heat trans
Infrared communications are useful for indoor use in areas of high population density. IR does not penetrate walls and so does not interfere with other devices in adjoining rooms. Infrared is the most common way for remote controls to command appliances.
- Examples of use
- Infrared pyrometer
An infrared thermometer is a thermometer which infers temperature from a portion of the thermal radiation sometimes called black-body radiation emitted by the object being measured. They are sometimes called laser thermometers as a laser is used to help aim the thermometer, or non-contact thermometers or temperature guns, to describe the device's ability to measure temperature from a distance. By knowing the amount of infrared energy emitted by the object and its emissivity, the object's tempera
Some typical circumstances are where the object to be measured is moving; where the object is surrounded by an electromagnetic field, as in induction heating; where the object is contained in a vacuum or another controlled atmosphere; or in applications where a fast response is required, the accurate surface temperature is desired or the object temperature is above the recommended use point for contact sensors, or contact with a sensor would mar the object or the sensor, or introduce a significa
Infrared thermometers are characterized by specifications including accuracy and angular coverage. Simpler instruments may have a measurement error of about ±2 °C or ±4 °F. The distance-to-spot ratio is the ratio of the distance to the measurement surface and the diameter of the temperature measurement area. For instance, if the D:S ratio is 12:1, the diameter of the measurement area is one-twelfth of the distance to the object. A thermometer with a higher ratio of D to S is able to ...
The most common infrared thermometer is the spot infrared pyrometer or infrared pyrometer, which measures the temperature at a spot on a surface. These usually project a visible red dot onto the center of the area being measured that identifies the spot being measured, but plays no part in the measurement. The actual angular area being measured varies among instruments and is not restricted to the visible spot. Related equipment, although not strictly thermometers, include infrared scanning syst
Infrared was discovered in 1800 by Sir William Herschel as a form of radiation beyond red light. These "infrared rays" (infra is the Latin prefix for "below") were used mainly for thermal measurement. There are four basic laws of IR radiation: Kirchhoff's law of thermal radiation, Stefan-Boltzmann law, Planck's law, and Wien's displacement law.
Infrared thermography (IRT), thermal imaging, and thermal video are examples of infrared imaging science. Thermographic cameras usually detect radiation in the long-infrared range of the electromagnetic spectrum (roughly 9,000–14,000 nanometers or 9–14 µm) and produce images of that radiation, called thermograms.