The so-called optical band refers to the electromagnetic spectrum band of interest in the optical field, and the electromagnetic waves in the optical band can be analyzed by optical theory, and can be easily generated and processed by optical methods. Light is a very frequent electromagnetic wave, so where is the optical band in the whole electromagnetic wave? Is it possible to divide the optical bands further?
The optical wavelength band we are talking about can be partly from the shadow in the diagram, which has a wavelength range from 10 nm to 300 μm, corresponding to frequencies from 1012 to the power of 1016 Hz, which spans about 4 orders of magnitude. Optical bands can be further divided into visible, infrared, and ultraviolet bands according to whether they are visible to our human eyes.
Visible wavelength range
The wavelength range of visible light is about 390 nm to 760 nm, and it corresponds to a frequency of 1014 Hz. The visible light bands can be further distinguished by color, and the wavelength range corresponding to different colors of light is roughly as follows:
- Red 620~760nm
- Orange light 600~620nm
- Yellow 570~600nm
- Green light 490~570nm
- Blu-ray 450~490nm
- Violet light 390~450nm
Infrared wavelength range
The wavelength of the infrared range is from 0.76~300μm, and the infrared (IR) band can be further divided into, near infrared (NIR), middle infrared (MIR) and far infrared (FIR).
- Near-infrared（NIR）0.76~2μm
- Mid-infrared（MIR）从2~20μm
- Far infrared（FIR）从20~30μm
Ultraviolet wavelength range
The ultraviolet (UV) band ranges from 10~390nm, and the ultraviolet band can be further divided into near ultraviolet (NUV), medium ultraviolet (MUV), far ultraviolet (FUV) and extreme ultraviolet (EUV).
- Near-ultraviolet（NUV）390~300nm
- Medium ultraviolet（MUV）200~300nm
- Far ultraviolet（FUV）100~200nm
- Extremely far ultraviolet（EUV）10~100nm
The 10~200nm band of ultraviolet light can only be applied in a vacuum environment due to the strong absorption effect of the atmosphere, so this band is also called vacuum ultraviolet band (VUV).
Other ranges
High-energy ray region
In the electromagnetic spectrum, which is shorter than ultraviolet, belongs to the region of high-energy rays, X-rays and γ-rays.
Terahertz band range
The shortest wavelength of radio waves is on the order of millimeters, and electromagnetic waves with longer wavelengths than millimeters are relatively easy to generate and process using electronic methods. There is a gap between the far infrared and microwave electromagnetic spectrum that is inconvenient to generate and process with electronic and optical methods, the frequency range of this gap is about 0.1THz~10THz, and the wavelength range is between 30um~3mm. This band is called the terahertz band, because the terahertz band has strong penetration ability and high security, it has a very important application prospect in radar, security, non-destructive testing and other fields.
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