A report on Light, Infrared and Laser

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.
A pseudocolor image of two people taken in long-wavelength infrared (body-temperature thermal) radiation.
Red (660 & 635 nm), green (532 & 520 nm) and blue-violet (445 & 405 nm) lasers
The electromagnetic spectrum, with the visible portion highlighted
This false-color infrared space telescope image has blue, green and red corresponding to 3.4, 4.6, and 12 μm wavelengths, respectively.
A laser beam used for welding
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Plot of atmospheric transmittance in part of the infrared region
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Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily
Materials with higher emissivity appear closer to their true temperature than materials that reflect more of their different-temperature surroundings. In this thermal image, the more reflective ceramic cylinder, reflecting the cooler surroundings, appears to be colder than its cubic container (made of more emissive silicon carbide), while in fact, they have the same temperature.
A helium–neon laser demonstration. The glow running through the center of the tube is an electric discharge. This glowing plasma is the gain medium for the laser. The laser produces a tiny, intense spot on the screen to the right. The center of the spot appears white because the image is overexposed there.
Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.
Active-infrared night vision: the camera illuminates the scene at infrared wavelengths invisible to the human eye. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor.
Spectrum of a helium–neon laser. The actual bandwidth is much narrower than shown; the spectrum is limited by the measuring apparatus.
Hong Kong illuminated by colourful artificial lighting.
Thermography helped to determine the temperature profile of the Space Shuttle thermal protection system during re-entry.
Lidar measurements of lunar topography made by Clementine mission.
Pierre Gassendi.
Hyperspectral thermal infrared emission measurement, an outdoor scan in winter conditions, ambient temperature −15 °C, image produced with a Specim LWIR hyperspectral imager. Relative radiance spectra from various targets in the image are shown with arrows. The infrared spectra of the different objects such as the watch clasp have clearly distinctive characteristics. The contrast level indicates the temperature of the object.
Laserlink point to point optical wireless network
Christiaan Huygens.
Infrared light from the LED of a remote control as recorded by a digital camera
Mercury Laser Altimeter (MLA) of the MESSENGER spacecraft
Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.
Reflected light photograph in various infrared spectra to illustrate the appearance as the wavelength of light changes.
Aleksandr Prokhorov
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Infrared hair dryer for hair salons, c. 2010s
Charles H. Townes
IR satellite picture of cumulonimbus clouds over the Great Plains of the United States.
LASER notebook: First page of the notebook wherein Gordon Gould coined the acronym LASER, and described the elements required to construct one. Manuscript text: "Some rough calculations on the feasibility / of a LASER: Light Amplification by Stimulated / Emission of Radiation. / Conceive a tube terminated by optically flat / [Sketch of a tube] / partially reflecting parallel mirrors..."
The greenhouse effect with molecules of methane, water, and carbon dioxide re-radiating solar heat
Graph showing the history of maximum laser pulse intensity throughout the past 40 years.
Beta Pictoris with its planet Beta Pictoris b, the light-blue dot off-center, as seen in infrared. It combines two images, the inner disc is at 3.6 μm.
Wavelengths of commercially available lasers. Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The color codifies the type of laser material (see the figure description for more details).
An infrared reflectogram of Mona Lisa by Leonardo da Vinci
A 50 W FASOR, based on a Nd:YAG laser, used at the Starfire Optical Range
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A 5.6 mm 'closed can' commercial laser diode, such as those used in a CD or DVD player
Thermographic image of a snake eating a mouse
Close-up of a table-top dye laser based on Rhodamine 6G
Infrared radiation was discovered in 1800 by William Herschel.
The free-electron laser FELIX at the FOM Institute for Plasma Physics Rijnhuizen, Nieuwegein
Infrared hair dryer for hair salons, c. 2010s
Lasers range in size from microscopic diode lasers (top) with numerous applications, to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion, nuclear weapons research and other high energy density physics experiments.
The US–Israeli Tactical High Energy weapon has been used to shoot down rockets and artillery shells.
Laser application in astronomical adaptive optics imaging

Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light.

- Infrared

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.

- Laser

Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).

- Light

However, particularly intense near-IR light (e.g., from IR lasers, IR LED sources, or from bright daylight with the visible light removed by colored gels) can be detected up to approximately 780 nm, and will be perceived as red light.

- Infrared

Emission can also be stimulated, as in a laser or a microwave maser.

- Light

As ideas developed, they abandoned infrared radiation to instead concentrate on visible light.

- Laser
A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.

2 related topics with Alpha

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Electromagnetic radiation

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In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, propagating through space, carrying electromagnetic radiant energy.

In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, propagating through space, carrying electromagnetic radiant energy.

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Shows the relative wavelengths of the electromagnetic waves of three different colours of light (blue, green, and red) with a distance scale in micrometers along the x-axis.
In electromagnetic radiation (such as microwaves from an antenna, shown here) the term "radiation" applies only to the parts of the electromagnetic field that radiate into infinite space and decrease in intensity by an inverse-square law of power, so that the total radiation energy that crosses through an imaginary spherical surface is the same, no matter how far away from the antenna the spherical surface is drawn. Electromagnetic radiation thus includes the far field part of the electromagnetic field around a transmitter. A part of the "near-field" close to the transmitter, forms part of the changing electromagnetic field, but does not count as electromagnetic radiation.
Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This 3D animation shows a plane linearly polarized wave propagating from left to right. The electric and magnetic fields in such a wave are in-phase with each other, reaching minima and maxima together.
Representation of the electric field vector of a wave of circularly polarized electromagnetic radiation.
James Clerk Maxwell
Electromagnetic spectrum with visible light highlighted
Rough plot of Earth's atmospheric absorption and scattering (or opacity) of various wavelengths of electromagnetic radiation

It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

In addition to infrared lasers, sufficiently intense visible and ultraviolet lasers can easily set paper afire.

Blue, green, and red LEDs in 5 mm diffused cases

Light-emitting diode

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Blue, green, and red LEDs in 5 mm diffused cases
Parts of a conventional LED. The flat bottom surfaces of the anvil and post embedded inside the epoxy act as anchors, to prevent the conductors from being forcefully pulled out via mechanical strain or vibration.
Close-up image of a surface mount LED
A bulb-shaped modern retrofit LED lamp with aluminum heat sink, a light diffusing dome and E27 screw base, using a built-in power supply working on mains voltage
Green electroluminescence from a point contact on a crystal of SiC recreates Round's original experiment from 1907.
A 1962 Texas Instruments SNX-100 GaAs LED contained in a TO-18 transistor metal case
LED display of a TI-30 scientific calculator (ca. 1978), which uses plastic lenses to increase the visible digit size
X-Ray of a 1970s 8-digit LED calculator display
Illustration of Haitz's law, showing improvement in light output per LED over time, with a logarithmic scale on the vertical axis
Blue LEDs
Combined spectral curves for blue, yellow-green, and high-brightness red solid-state semiconductor LEDs. FWHM spectral bandwidth is approximately 24–27 nm for all three colors.
RGB LED
Spectrum of a white LED showing blue light directly emitted by the GaN-based LED (peak at about 465 nm) and the more broadband Stokes-shifted light emitted by the Ce3+:YAG phosphor, which emits at roughly 500–700 nm
LEDs are produced in a variety of shapes and sizes. The color of the plastic lens is often the same as the actual color of light emitted, but not always. For instance, purple plastic is often used for infrared LEDs, and most blue devices have colorless housings. Modern high-power LEDs such as those used for lighting and backlighting are generally found in surface-mount technology (SMT) packages (not shown).
Image of miniature surface mount LEDs in most common sizes. They can be much smaller than a traditional 5mm lamp type LED, shown on the upper left corner.
Very small (1.6×1.6×0.35mm) red, green, and blue surface mount miniature LED package with gold wire bonding details.
High-power light-emitting diodes attached to an LED star base (Luxeon, Lumileds)
RGB-SMD-LED
Composite image of an 11 × 44 LED matrix lapel name tag display using 1608/0603-type SMD LEDs. Top: A little over half of the 21 × 86 mm display. Center: Close-up of LEDs in ambient light. Bottom: LEDs in their own red light.
Simple LED circuit with resistor for current limiting
Daytime running light LEDs of an automobile
Red and green LED traffic signals
LED for miners, to increase visibility inside mines
Los Angeles Vincent Thomas Bridge illuminated with blue LEDs
LED costume for stage performers
LED wallpaper by Meystyle
A large LED display behind a disc jockey
Seven-segment display that can display four digits and points
LED panel light source used in an experiment on plant growth. The findings of such experiments may be used to grow food in space on long duration missions.

A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it.

Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light.

Unlike a laser, the light emitted from an LED is neither spectrally coherent nor even highly monochromatic.