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Monochromatic Light

Last updated date: 17th Apr 2024
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What is Monochromatic Light?

Light is the key wellspring of energy on Earth. Light is of different wavelengths grouped in view of its properties and behaviour. Light shows different properties like Diffraction, Reflection, Refraction, Polarisation, and Interference. Electromagnetic radiations comprise different wavelengths of light.

Innovations using monochromatic light have an extensive variety of applications, from astronomy and astrophysics to forensic science. To answer the question of what is monochromatic light or monochromatic light definition, let’s understand the term itself. The term monochromatic comes from the Greek words monos, meaning one or single, and chromos, meaning colour. Monochromatic light, or one-variety light, is basically electromagnetic radiation gotten from photon discharges from atoms. Photons engender, or travel, as energy wave fronts of various lengths and levels of energy. Energy levels decide the recurrence of light, and the length of a wave decides its colour. The groups of light frequencies that people can see are called visible light.

Theodore Maiman

Theodore Harold Maiman, an American engineer and physicist (July 11, 1927-May 5, 2007), is widely recognised as the father of the laser. Numerous more kinds of lasers were later developed as a result of Maiman's laser. On May 16, 1960, the laser was successfully fired. Maiman and his employer, Hughes Aircraft Company, introduced the laser to the world on July 7, 1960, in Manhattan.

Theodore Maiman

Theodore Maiman

Source of Monochromatic Light

Lasers are an essential source of monochromatic light. As opposed to narrow-band light obtained by bandpass filtering light from a broadband source, lasers can create semi-monochromatic light with high optical powers. A few lasers even show outrageous levels of monochromaticity, i.e., a tiny optical bandwidth. The most significant level of monochromaticity is accomplished with carefully balanced out single-frequency lasers.

The antonym of monochromatic is polychromatic. A normal model for polychromatic light is life made as thermal radiation, for example in an incandescent light; such light shows an expansive scope of optical frequencies.

Numerous computations in optics and photonics are performed for monochromatic light. For instance, the development of laser radiates is generally determined that way; there is only one given optical frequency or wavelength.

Monochromatic light can be separated from polychromatic light utilising a monochromator. Before the approach of the laser, delivering monochromatic light was very difficult. One chance was to utilise certain gas-release lamps and metal vapour lamps (for example, mercury vapour lamps and sodium vapour lamps), emanating light predominantly in specific narrow spectral lines and isolating one such line with a reasonable monochromator. The accomplished optical powers and intensities were very low.

A monochromator is basically a sort of optical channel which permits one to separate light in a narrow spectral interval from other light. Its result will be quasi-monochromatic. Nevertheless, the light at any remaining frequencies is then lost.

Properties of Monochromatic Light

Now, let us study a few important properties of monochromatic light.

  • Monochromatic light is made up of a relatively small bandwidth of wavelengths.

  • The intensity of monochromatic light is extremely high.

  • Because monochromatic light is coherent, it is focused in a very narrow area, and can not be spread apart from the point of focus.

  • In a straight line, monochromatic light can travel incredibly vast distances.

  • Since the light has a relatively small wavelength bandwidth, monochromatic light appears as a single colour in the visible region.

  • The energy of monochromatic light is extremely high.

Types of Monochromator

  • Prism monochromator

  • Grating monochromator

In prism monochromators, a prism is utilised as a dispersive component, and in grating monochromators, a reflecting diffraction grating is utilised as a dispersive component.

Monochromatic Light Examples

There exist different monochromatic sources of light in our day-to-day routine. Some of them are recorded beneath:

  • LASER is an abbreviation for light intensification by stimulated emission of radiation. A LASER light delivers a profoundly directional, single-coloured, and intense light emission. Generally, LASER radiates are red, green, or blue in variety.

  • Sodium light is normally light golden yellow in variety and is one of the most mind-blowing examples of monochromatic light utilised in our regular routine.

  • The light transmitted by a light-emitted diode(LED) is regularly monochromatic in nature as it doesn't contain photons that have a place with various wavelength bands.

  • A spark lamp is one of the most mind-blowing examples of monochromatic sources of light. They normally utilise a LED bulb to create light radiations into the environment.

Applications of Monochromatic light

  • Ultraviolet monochromatic gadgets are utilised in crime scenes to discover explicit and sensitive proof. Monochromatic light assists with perceiving hidden bloodstains, fingerprints, and sores under the skin.

  • The holograms engraved on credit cards, money notes, and different records are generally made with the help of monochromatic laser lights. Likewise, 3D holograms normally are shown with the help of monochromatic light beams.


Monochromatic light has definitively only one frequency, yet practically speaking this is not possible, and thus monochromatic light generally comprises a (little) bandwidth of wavelength. If monochromatic light is in the visible spectrum, the colour that can be seen by the natural eye is known as spectral colour.

A monochromator secludes monochromatic light from a broadband light source; lasers create monochromatic light directly. The monochromatic word comes from Greek where monos means single and chromos means colour. So, monochromatic light is a single wavelength light. The main source of monochromatic light is a Laser beam. Before the approach of the laser, monochromatic light can be separated from polychromatic light utilising a monochromator. Monochromatic lights are used in forensics to scan bloodstains, fingerprints, and so on.

Competitive Exams after 12th Science

FAQs on Monochromatic Light

1. What is the use of a spectrophotometer?

A spectrophotometer is an instrument that is used to measure the number of photons retained after it goes through the sample solution. With the spectrophotometer, we can also determine the chemical substance by estimating the intensity of light identified.

2. Does light behave like a wave or particle? Explain.

Light can behave both as a wave and as a particle. While we're considering light being made of particles, these particles are classified as "photons". Photons have no mass, and everyone conveys a particular measure of energy. In the interim, when we consider light propagating as waves, these are waves of electromagnetic radiation.

3. What is laser light?

Laser light has a property like that of light waves transmitted at the same time. They are coherent, and normally of one wavelength (or colour).