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Why Blue Laser Pointers are Much More Expensive Than Green Laser Pointers

One of the most obvious differences between a blue laser pointer and a green laser pointer is price. A 10 mW blue laser pointer cost $700 compared to the price of the equivalent 15mW green laser pointer that cost $100.

It is not just blue laser pointers that are more expensive. Blue laser modules, OEM lasers and lab lasers are also much more expensive than their green counterparts. The reason for such a large price differences are the processes used to generate the laser beam, the components used that the manufacturing volumes.

Beam generation process

Both blue and green laser pointers use a pump diode that gives out infrared 808nm light that is used to pump the same type of crystals. The pumped crystals in turn give out light in the far infrared spectrum. The difference between blue and green lasers is the optical coatings on the pumped crystals and the type of far infrared light produced by these crystals.

The pumped crystals in a green laser pointer have an optical coating that causes the crystals to give out mostly 1064nm infrared light that is frequency doubled by another crystal to green 532nm light. The pumped crystals in a blue laser pointer have a different coating that causes the crystals to give out mostly 946nm infrared light that is also frequency doubled by another crystal to 473nm light.

The components

The process of producing 1064nm light is much more efficient than making 946nm light so blue laser pointers need a large pump diode to produce the same power. The larger pump diode makes blue laser pointers more expensive. The frequency doubling crystals in blue laser pointers are rarer and more expensive than those in green laser pointers.

Manufacturing volumes

Green laser pointers have better visibility than blue laser pointers and have less temperature problems at higher power levels. This means that green lasers are used for a larger number of diverse applications such as astronomy, pointing, burning and signaling and are manufactured in very high volumes. Blue laser pointers on the other hand are much more limited in their application and are manufactured in much lower volumes. Like any product, the lower the volume produced, the more expensive the product is.

Article is courtesy of Dragonlasers - No 1 lasers, laser pointer and green laser online store

About the Author

Frank is from Dragonlasers at http://www.dragonlasers.com

Harmonized code for Laser diodes and DPSS Lasers?

The present invention relates to bar code reading systems and particularly to a bar code reader which is adapted for portable operation by conserving the electrical power utilized to operate the reader while at the same time limiting output optical power in the form of laser radiation to those prescribed by governmental regulation.

The invention is especially suitable for use in laser bar code readers and scanners (the term reader including scanners which scan a light beam across the bar code). However, the invention may also be utilized in fixed station bar code systems where radiation level limitation and efficiency of operation is desired.

Limitation of laser radiation is subject to regulatory restrictions in output power. Present regulations in the United States by the Center for Devices and Radiological Health (CDRH) require the output power of a practical (i.e., Class II) laser bar code scanner operating in the visible region of the spectrum to an average of 1 milliwatt (mw). Visible laser diode scanners which are presently available exhibit cw output power of 3 to 5 mw. 3 mw output power is obtained from model TLD 9200 manufactured by the Toshiba Corporation of Japan. CW power output of laser diodes may shortly exceed 10 mw. These governmental restrictions and other approaches for their accommodation in bar code systems are discussed in U.S. Pat. No. 4,639,606 entitled "Bar Code Scanner Laser Radiation Limit Control System", issued to John Boles and Jay Eastman on Jan. 27, 1987.

In a typical laser diode bar code scanner as shown in FIG. 1, a DC voltage reference 10 serves as an input to a laser regulator circuit 12. The regulator powers the laser diode 14 in a cw manner. The output from the laser is shaped by suitable optics (not shown) and scanned across the bar code by a scanning mechanism (not shown). Scattered light from the bar code is detected by a photodetector 16, ac coupled by a capacitor 18 and amplified by a band limited preamplifier 20. The preamplifier typically utilizes high and low pass filters that surround the frequencies present in the analogue bar code signal. The preamplifier also commonly contains an automatic gain control function (AGC). The output from the preamplifier is presented to a digitizer circuit 22 that converts the analogue signal corresponding to the bar code to a digital representation of the bar code. This digitized bar code signal may be decoded by bar code decoder equipment. Such a system operates in a cw mode. The optical power is limited to the level (1 mw) specified by regulatory restrictions.

It has been discovered in accordance with the invention that the operating current applied to the laser may be substantially reduced without degradation in the reading performance of the system and power consumption (i.e., current consumption) may likewise be reduced thereby specially benefitting portable battery powered devices, such as hand held bar code scanners. Such power conservation and radiation limiting advantages are obtained by operating the light source (laser) in a pulse mode rather than a cw mode but in a portion of the optical power vs operating current characteristic of the light source which obtains the power conservation and radiation limitation (without degradation in reading performance) advantages.

for more info..link...click on

http://math.nist.gov/mcsd/savg/others/photonics/

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