640 nm light

640 nm light DEFAULT

What Wavelengths and Colors do

To understand how your crops are going to react on different wavelengths and colors, you have to keep in mind that every crop and every growth stage requires an individual approach.

LED Grow Light Absorption curves of plants

The amount of light affects the photosynthesis process in the plant.

This process is a photochemical reaction within the chloroplasts of the plant cells in which CO₂ is converted into carbohydrate under the influence of the light energy.

The spectral composition of the different wavelength regions (blue, green, yellow, red, far red or invisible e.g. UV or IR) is important for the grows, shape, development and flowering (photomorphogenesis) of the plant.

For the photosynthesis, the blue and red regions are most important.

The timing / light duration which is also called photoperiod is mainly affecting the flowering of the plants. The flowering time can be influenced by controlling the photoperiod.

Photosynthetic efficiency is mainly driven by chlorophyll a and b.

Chlorophyll a and b are mainly responsible for the photosynthesis and responsible for the definition of the area for the photosynthetically active radiation PAR.

The Photosynthetically active radiation (PAR) shows further photosynthetic pigments also known as antenna pigments like carotenoids - carotene, zeaxanthin, lycopene and lutein etc.

Wavelength range [nm]PhotosyntesisFurther EffectsFurther EffectsFurther Effects
200 – 280
Harmful

280 – 315
Harmful

315 – 380



380 – 400Yes


400 – 520YesVegetative growth

520 – 610SomeVegetative growth

610 – 720YesVegetative growthFloweringBudding
720 – 1000
GerminationLeaf building and growthFlowering
> 1000
Converted to heat

The Phytochromes Pr (red) and Pfr (far red) are mainly influencing the germination, plant growth, leave building and flowering.

The phytomorphogenic effects are controlled by applying a spectrum with a certain mix of 660nm and 730nm in order to stimulate the Pr and Pfr phytochromes.



Sours: https://www.horti-growlight.com/en-gb/what-wavelengths-colors-do

Visible spectrum



The visible spectrum is a very small portion of the electromagnetic spectrum that can be seen by the human eye. This is summarized in the figure below, which is not to scale. The exact boundaries of each type of wave are not precisely defined and often different authors have slightly different values. This is not really relevant since this classification is just indicative.

Electromagnetic spectrum (not to scale)
The electromagnetic spectrum (not to scale).

As frequency increases the wavelength becomes smaller and the energy associated to each photon increases. Visible light, infrared and radiation with longer wavelengths are non-ionizing radiations. UV light, X rays, gamma rays and radiations with shorter wavelength are ionizing radiations, meaning that each photon carries enough energy to ionize matter. When a ionizing photon with enough energy impinges on an atom or on a molecule, it can knock off one electron from it. Having lost an electron, the atom (or molecule) becomes electrically charged and is called an ion. Because of their electrical charge, ions are chemically very active and tend to react with nearby molecules. The limit between ionizing and non-ionizing radiations is located somewhere in the UV region, but it's not clearly defined and somehow fuzzy. A photon energy1 of 10 eV (corresponding to a wavelength of 124 nm) is often considered the threshold between ionizing and non-ionizing radiation, but there is no consensus on this topic.

The wavelengths2 of the visible spectrum are usually between 400 nm and 700 nm. The energy carried by each visible photon is between 3.1 eV and 1.8 eV respectively and the frequency is in the 750 THz to 428 THz range

The sensitivity of the eye to wavelengths beyond this range drops dramatically and they are represented as black in the figure below. The maximum sensitivity is usually between 500 and 550 nm.

Visible spectrum
The visible spectrum.

The perceived color dependens on the wavelength and the table below will give a rough idea. Of course, this varies from one person to another.

Red700...630 nm
Orange630...600 nm
Yellow600...570 nm
Green570...530 nm
Cyan530...490 nm
Indigo490...450 nm
Blue450...400 nm

You may be surprised that the color called violet actually looks blue and that there is no purple nor pink: this is because in the 17th century when Newton discovered the spectrum of the sunlight, the names of the colors corresponded to slightly different hues. He called violet what we would call blue today and blue what we would call cyan. You may also think at the famous poem "roses are red and violets are blue", the hue of the violets is actually blue...

Purple and pink, on the other hand, are colors that do not correspond to an unique wavelength, they are perceived by eye when both blue and red light are superposed. Since blue and red are at opposite sides of the visible spectrum, no single wavelength will appear purple or pink.

Talking about missing colors, there is no brown nor grey light neither: these colors are just perceived when compared with other brighter colors, gray is a dim white and brown is a dim yellow/orange.

Wavelengths shorter than 390 nm are part of the UV spectrum and are not visible; UV meaning ultra violet, beyond violet (meaning blue). Wavelengths longer than 750 nm are part of the IR spectrum and are not visible neither; IR meaning infrared, below red. It's not possible to give a precise boundary between visible and invisible wavelengths since that's very subjective: some people may still see some light at 720 nm and some others may not.


White light, a superposition of all colors, can be decomposed with a prism to observe its spectrum. Just shining light at a prism is not enough; the light has to go through a narrow slit to let only a small ray pass through. The quality of this slit is very important for the precision of the result. In the example below, the slit is just a crude cut in a piece of cardboard and makes a very rough spectrometer, but still enough to observe a "rainbow".

Visible spectrum of white light observed with a prism
Visible spectrum of white light observed with a prism.


Bibliography and further reading

[1]Warren J. Smith. Modern Optical Engineering - The Design of Optical Systems. 3rd Edition, McGraw-Hill, 2000, section 1.1.
[2]Eugene Hecht. Optics. 4th Edition, Addison Wesley, 2002, section 3.6.

Notes

1: The energy of a photon of a given wavelength id given by Planck's law E = hν or E = hc/λ where E is the photon energy in electronvolt (eV), h is Plank's constant 4.135'667'517·10−15 eV·s, c is the speed of light 299'792'458 m/s, ν is the photon frequency in Hertz and λ is the photon wavelength in meters.
2: 1 nm = 10–9 m = 0.000'000'001 m
1 THz = 1012 Hz = 1'000'000'000'000 Hz


Sours: https://www.giangrandi.org/optics/spectrum/spectrum.shtml
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Wavelength vs. Color

Each wavelength in nanometers is displayed in its approximate color

By Oguz Yetkinhttp://www.cs.wisc.edu/~yetkin

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Sours: http://pages.cs.wisc.edu/~yetkin/code/wavelength_to_rgb/wavelength.html
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Light 640 nm

Red light therapy involves exposure to fairly strong sources of visible red light (610-700nm).

As a natural, non-invasive method there are a wide variety of applications being studied.

Most of the studies and interest is around the use to treat skin conditions, but there are a whole host of further applications.
The beauty of this type of treatment is that there are no significant side effects doucmented, yet a long and well studied list of applications.

Contents

How it works
The Wavelengths of Red Light Therapy
What does it do in the cell?
Who does it benefit?
Can it be used for beauty?
What is the standard treatment like?
How often can it be used?
Risks?
Which light source is best?

How it works

red light through hand
Red light interacts with the body in a similar way to infrared light – This it thought to involve a few mechanisms including by increasing energy (ATP) generation on the cellular level.

The key difference between red and infrared is that red wavelengths of light are absorbed and used in the first 25mm of skin tissue, whereas infrared light can penetrate much deeper into the body.

This same mechanism is also responsible for many of the benefits of sunlight, which contains the red wavelengths as part of its spectrum. Sunlight however, comes bundled with potentially harmful UV (and potentially beneficial) & blue light, making red light therapy different in various respects.

Most red light devices on the market are weak and will only penetrate 2 – 3mm of skin tissue. Stronger devices such as 100mW/cm²+ LED light devices can reach through the entire skin layer, healing from the bottom up.

The Wavelengths of Red Light Therapy

Red light therapy uses any wavelength between 610 nm and 700 nm.

red-wavelengths
red light therapy optimum wavelength spectrum graph

The most common wavelengths you will see are 630 nm (orange-red) and 660 nm (deep red) which roughly coincide with the absorption peaks of cytochrome c oxidase (the target of light therapy), plus they are cheaply available and efficient. While effective, these are not necessarily the perfectly optimal wavelengths.

The absolute optimal spectrum ranges are 610-625nm & 660-690nm.

The absolute optimal single wavelengths are 620nm and 670nm.

These optimal wavelengths vary to some degree in different studies and different cells. 615nm and 680nm are also sometimes optimal.

What specifically does it do in the cell?

It is thought by researchers that there are a variety of cellular structures that absorb light energy, most notably the mitochondria:

  • Our mitochondria can absorb red light due to a key energy producing copper enzyme (cytochrome c oxidase – link) which absorbs light at various wavelengths between 600-1000nm.
  • Metabolism in the mitochondria is usually restricted by a biologically active molecule called nitric oxide, which binds to cytochrome oxidase and prevents it from using oxygen. Red light acts by photodissociating (or detaching) this nitric oxide molecule, allowing cytochrome to resume its energy producing metabolic function.
  • Red light has been shown to improve the structure of water in cellular cytoplasm and other areas of the body, potentially providing a functional benefit to all cellular processes. The improved surface tension of cells may also improve ion exchange.
  • Through a complex but well understood process, cytochrome helps to synthesise ATP
  • Red light increases ROS (reactive oxygen species) which have a positive stimulatory effect in low amounts.

 

Who can use it?

Red light therapy is entirely safe and non-invasive, meaning it can be used by anyone – young or old.

The current hyptohesis (on the mechanism of action) points to a foundational level of the body, meaning a potentially wide array of useful applications.

What is the standard treatment like?

The light is simply used for a short amount of time (5 – 15 minutes), after which further therapy would show quickly diminishing returns.

This is known as a biphasic dose response – lower doses give a good effect, very high doses cancel out this effect. The reason why longer session times gives diminshing returns is not very well understood, possibly involving heating of the skin cells, ROS or nitric oxide release.

Regardless, a short therapy session gives better results than constant use for hours on end.

red light device with cytochrome absorption

How often can it be used?

The red light would ideally be used 3-4 days per week to start off with and continue like that for 4-6 weeks.

For general maintenance and health once or twice a week is acceptable.

Are there any risks from red light therapy?

There are many interesting applications for red light therapy, but what about the risks?

  • There are no serious side effects documented in the literature.

LED, incandescent, heat lamp, etc. Which light source is best?

There are a wide variety of devices capable of outputting beneficial wavelengths of red light, including; LED, lasers, incandescent, halogen, low level laser, fluorescent, etc.graph of led vs light efficiency

All sources of red light are not equally useful however, with some being inappropriate for light therapy. Research focuses on the energy efficient and low heat sources of red light such as LEDs and lasers. Devices like red heat lamps have some overlapping wavelengths with red light therapy, but heat denatures the target cytochrome enzyme.

The reasons why red LED devices stand out from the rest include:

  • The most energy efficient
    • Most lumens per watt
    • Less energy wasted as heat
  • The longest lasting (50000 hours)
  • More specific wavelengths available
  • Does not heat the skin (or denature target enzymes)
  • Very well studied
  • Safe all over the body

 

Medical & Healthcare Disclaimer
The information contained in this article is not intended or implicitly suggested to be an alternative for professional diagnoses, or profesionally recommended treatments & medical advice. Absolutely all of the content, including the article text itself, images, comments and other information, contained on this web page is for non-specific information purposes only. We strongly suggest that one should never ignore professional health/medical advice and we strongly suggest that one must not delay seeking a professionally recommended medical treatment because of information attained via reading this article/website. The products sold or recommended on this web site are absolutely not for the diagnosis, prevention, monitoring, treatment or alleviation of any specific disease, injury or disability.

Sours: https://redlightman.com/light-therapy/red/
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