Laser Pointer

Laser pointer is a kind of pen, portable or handheld designed laser devices manufactured from laser module (laser diode). Common laser pointers includes red (635nm, 650nm), green (515nm, 520nm, 532nm), blue violet (405nm), blue (445nm, 450nm, 460nm), yellow (589nm), infrared (808nm, 980nm) infrared laser pointers. Laser pointer is able to emit a long distance visible beam for presentation on targeted objects. However, it might corrupt or affect the workplace navigation objects, such as museum of art or zoo etc. Laser pointer is not recommended in these places.

History
The earliest laser pointer with a wavelength of 633nm is helium-neon (HeNe) gas laser, typically used to generate energy less than 1mW laser beam. The cheapest laser pointer uses red laser diode of wavelength close to 670/650nm. Slightly more expensive laser pointer uses 635nm red-orange laser diode, which is more easily identified by human eyes. There are also other color laser pointers such as 532nm green laser pointer is also available on the market. Early in 21st century, 5933.5nm yellow-orange laser pointer appeared, 473nm blue laser pointer appeared in Sep. 2005, and 405nm blue violet laser pointer appeared in 2010.

Features of laser pointers
Brightness
The irradiated laser light spot from laser pointer not only depends on the power and apparent brightness of surface reflectance of laser beam, also the color vision of the human eyes since human eyes are most sensitive to green light among wavelength range of 520nm-570nm. Human eyes have weaker sensitivity to blue or red light, thus green laser pointer seems brighter than other color lasers with the same power.

Power
Laser pointer power uses milliwatt. In United States, laser is classified by American National Standards Institute and U.S. Food and Drug Administration (FDA). Laser pointers are classified as below:
Class 2 or II: visible laser pointer (400-700nm) less than 1mW
Class 3A or IIIa: laser pointer among 1mW to 5mW
Class 3B/IIIB: laser pointer among power 5mW to 500mW
Class 4/IV: laser power up 500mW

Laser pointer classification
Red Laser Pointer or Red – Orange Laser Pointer
Red laser pointers are being designed with the simplest structure of 635nm or 650nm red laser diodes, easily operable by battery. Red laser pointer appears on the market in the early 21st century at low price and compact design, and 671nm DPSS red laser pointer appears at the same time. DPSS red laser technology assures high product quality and narrower band laser pointer.

Yellow Laser Pointer
593.5nm yellow laser pointer appeared in the early 21st century, available on basis of DPSS technology through a nonlinear crystal adding by 1064nm and 1342nm laser beam. The complex process has made yellow laser pointer inefficient and unstable, low output power of 1mW to 10mW. In addition, majority 593.5nm yellow laser pointers operate in pulse mode using a smaller size and low power pump diode.

Green Laser Pointer
Utilizing 808nm infrared laser excitation nonlinear crystal to produce 1064nm infrared laser light, and then multiplier produces 532nm green laser pointer, belongs to solid-state laser. Some green lasers operate in pulse or quasi-continuous mode to reduce cooling problem and prolong battery life.

Low power green laser pointer is visible even at night since scattering by atmospheric molecules. This laser device is often used for astronomy star and constellation pointing by astronomy enthusiasts or astronomers. 5mW green laser pointer (Class IIIa) is the safest laser for astronomy with visible beam in darkness. There is no need to select higher power laser for astronomy projection.

Blue Laser Pointer
473nm DPSS green laser pointer is low power and unstable. Early in 21st century, high power 445nm blue laser came in market usually in portable or handheld design. 460nm blue laser with the purest blue light is always available in pen design mainly used for projection.

Blue violet laser pointer
405nm blue violet laser pointer belongs to semiconductor laser, close to ultraviolet light, low visibility, but can stimulate fluorescence. It is applicable for paper money detection, chemicals test.

Laser Pointer Applications
Laser pointers are usually used as an eye-catching point in education, business presentation, and visual demonstrations.
● Red laser pointer can be used in almost any indoor or low light situations, pointing out details by hand may be convenient.
● Green laser pointer can be used for astronomy enthusiasts.
Green laser beam in moonless light, often can be seen clearly, accurately pointing out individual stars to others nearby. In addition, green laser pointer can be used by astronomers in astronomy lectures, which can direct a specific location of star or constellation accurately. Laser alignment is more easily by using eyepiece.
● Tour guide
Laser pointer makes convenient and rapid targeting of tentacles difficult objectives. It can accurately indicate target.
● Wide travelers and explorers
Laser pointers can be used in outdoor adventure, indicating distant targets and issuing distress signal to make travel more secure.
● Construction sites and mining field
Laser pointers makes precise instructions for remote buildings, avoids approaching the danger zone, and commander kilometer away field easily.
● Fire, rescue, help, and earthquake
Laser pointer is especially important in many emergency life-saving occasions.
● Entertainment
Low level power laser pointers can add good entertainment atmosphere in bars, gatherings.
● Industry lasers
Laser pointers can be used in industrial field. For instance, Construction Company may use high quality laser pointer in order to improve accuracy of specific distance from the display in large project.
● Scientific research
Laser pointers can also be applicable in scientific research field, such as photonics, chemistry, physics, and medicine and so on.

Laser pointer hazards and Laser Safety

● Laser pointer is harmful to human eyes. Never point lasers to human eyes directly, keep it away from child in order to avoid accidental injury. Please wear laser safety glasses while using a laser pointer indoor or close operation. Avoid direct eye stare at laser beams.

● Do not continuous light laser pointer too long (especially green laser), in summer no more than 30 seconds. Please stop laser pointer immediately if laser pointer feels hot until completely cooled.

● Green laser pointer may need to warm-up for some time in winter. It can be placed in a pocket to warm it up, put in battery, continuous light time is not more than one minute. It can prevent excessive aging of laser pointer or overheating to damage laser diode or laser module of laser pointers.
● Laser pointers cannot be used in the zoo for free frightened animal.
● Astronomy amateurs in the use of laser pointer for star pointing should not frequent and prolonged use of laser pointer, so as not to interfere with other people stargazing and photography.
● Stop using laser pointer in crowed public places in order to avoid harming others.
● High power laser pointers with significant thermal effects cannot be used continuously for a long time, especially for temperature sensitive solid state laser.
Article Resource: http://www.berlinlasers.com/laser-tech