In news- Scientists have found that the natural indigo dye extracted from leaves of a plant of the bean family is capable of protecting human eyes from harmful laser radiation.
About the dye-
- The blue dye is extracted from Indigofera Tinctoria or the famed Indigo plants that has been used over the years to colour clothes and clothing materials.
- Researchers from the Raman Research Institute (RRI), Bengaluru, and Kensri School and College, Bengaluru, studied the optical properties of the natural Indigo dye and found that it can act as a device to protect human eyes from harmful laser radiation.
- The study is funded by the Department of Science and Technology, Government of India and was published in the journal ‘Optical Materials’.
- The researchers extracted the dye and stored it in a refrigerator below 4º Celsius to preserve its natural properties.
- Their study on how much it absorbed light at different wavelengths of the electromagnetic spectrum showed that the absorption is maximum in the ultraviolet region of the spectrum.
- The absorption is comparatively high for the green light as well.
- The absorption’s variation with wavelength indicated that chlorophyll, an organic compound that takes part in photosynthesis, is present in the dye.
- The team found that when the intensity of the laser pulse is increased, the dye absorbs more light.
- Thus it is more opaque to higher intensity light and is referred to as an ‘optical limiter’.
- Optical limiters are useful in weakening the potentially harmful radiation emitted by powerful lasers and protecting both eyes and sensitive optical instruments.
- It is also called true indigo, is a species of plant from the bean family that was one of the original sources of indigo dye.
- It is a shrub one to two meters high and may be an annual, biennial, or perennial, depending on the climate in which it is grown.
- It has been naturalized to tropical and temperate Asia, as well as parts of Africa, but its native habitat is unknown.
- The natural dye from I. tinctoria is known as tarum in Indonesia and nila in Malaysia.
- In Iran and areas of the former Soviet Union it is known as basma.
- It has light green pinnate leaves and sheafs of pink or violet flowers.
- The plant is a legume, so it is rotated into fields to improve the soil.
- The plant’s leaves are soaked in water and fermented in order to convert the glycoside indican naturally present in the plant to the blue dye indigotin.
- The precipitate from the fermented leaf solution is mixed with a strong base such as lye.
- Marco Polo (13th century) was the first European to report on the preparation of indigo in India.
- Indigo was quite often used in European easel painting, beginning in the Middle Ages.