Laser Pointer's types and history

By Josh Edward | 21 December 2016 | 1 Comments
Early laser pens used helium-neon (HeNe) gas lasers with a wavelength of 633 nanometers (nm) and were typically used to generate laser beams with energy not exceeding 1 mW. The cheapest laser pen uses a deep red laser diode with a wavelength close to 670 / 650nm. A slightly expensive red-orange diode with a wavelength of 635 nm is used, which is more easily identified by the human eye. There are other colors of the laser pen, the most common is the 532nm wavelength of green light.

In recent years, 593.5nm yellow - orange laser pen also began to appear. September 2005 appeared in the 473nm blue laser pointer. At the beginning of 2010 there was a wavelength of 405nm "blue violet" laser pointer.

The apparent brightness of the laser beam illuminating the spot depends not only on the power and surface reflectivity of the laser, but also on the color perception of the human eye. For example, since the human eye is most sensitive to green light having a wavelength of 520-570 nm in the visible spectrum, the wavelength sensitivity to redder or bluer wavelengths decreases, so that green light appears brighter than other colors at the same power.

The power of the laser pointer usually in mW units. In the United States, lasers are classified by the American National Standards Institute and the US Food and Drug Administration (FDA). (Class 2 or Class II) with a power of less than 1 mW (wavelength 400-700 nm); Class A (Class 3A or IIIa) with a power rating of 1-5 mW. Class III (Class 3B / IIIb) lasers (5-500mW) and Class 4 / IV lasers (power greater than 500mW) can not be marketed under the laser pen.

Red Laser

Due to the wavelength of the laser diode, so the structure of the most simple, basically just a battery to do energy diodes. Red laser pen first appeared in the 1980s, is a huge bulky value of hundreds of dollars of units; now is very small and very cheap. In recent years, a diode-pumped solid-state laser (DPSS) red laser with a wavelength of 671 nm has been developed. Although this wavelength can be obtained with inexpensive diodes, DPSS technology can produce higher quality, narrower band laser.

Yellow light

The market appeared on the 593.5nm wavelength of the yellow laser pointer. Based on the DPSS technique, two laser beams with wavelengths of 1064nm and 1342nm are added through a nonlinear crystal. The complexity of the process makes the yellow laser pointer unstable and low efficiency, with the temperature output power in the 1-10mW, if the overheating or overheating will occur mode jump. This is because the size of the laser pen does not provide the required temperature stability and cooling components. In addition, most 593.5 nm laser pens operate in pulsed mode to use pump diodes with reduced size and power.

Green Laser

Using 808nm wavelength infrared laser excitation nonlinear crystals, resulting in 1064nm infrared light, and then generated by the multiplier frequency 532nm green light, are solid-state lasers.
Some green lasers operate in either pulse or quasi-continuous mode to reduce cooling problems and extend battery life.
The announced green laser that does not require multiplier has a higher efficiency.
At night even low-power green light can be seen because of the Rayleigh scattering of atmospheric molecules, which are often used by astronomers for pointing stars and constellations. Green laser pointer can have a variety of output power. 5mW is safest to use, and is also visible under dark lighting, so there is no need for more power for pointing purposes.

Blu-ray

The original only by DPSS produced 473nm blue laser, power is low and unstable. As CASIO developed mixed-source high-brightness projectors with blue laser diodes (445nm), blue-light semiconductor diodes with power exceeding 1000mW (Class 4) were mass-produced and mass-produced.

Purple light

The use of wavelength 405nm blue-violet laser diode, a semiconductor laser, close to the UV band, low visibility, but can stimulate fluorescence, with the notes and test chemicals.
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