Laser In Every Scientific Discipline

Published Date: 02 Nov 2017

words sends out light (http://en.wikipedia.org/wiki/Electromagnetic_radiationelectromagnetic radiation) through a process of http://en.wikipedia.org

wiki/Optical_amplificationoptical amplification based on the http://en.wikipedia.org/wiki/Stimulated_emissionstimulated emission of http://en

wikipedia.org/wiki/Photonphotons. The term "laser" originated as an http://en.wikipedia.org/wiki/Acronymacronym (A word formed from the initial

letters of a certain expression) for Light Amplification by Stimulated Emission of Radiation. The emitted laser light is remarkable for its high

degree of http://en.wikipedia.org/wiki/Coherence_%28physics%29coherence, both spatially and temporally. As stated above, the word laser started as

an http://en.wikipedia.org/wiki/Acronymacronym for "light amplification by stimulated emission of radiation"; in modern usage "light" roughly denotes

electromagnetic radiation of any frequency or several types of light, not only http://en.wikipedia.org/wiki/Visible_lightvisible light, hence are the

terms infrared laser, ultraviolet laser, X-ray laser,each according to the light frequency it emits, and so on. The maser preceded the laser which

was really the microwave predecessor of the laser. The maser was developed first, devices of this type operating at microwave and http://en

wikipedia.org/wiki/Radio_frequencyradio frequencies are referred to as "masers" rather than "microwave lasers" or "radio lasers". In the early

technical literature, especially at http://en.wikipedia.org/wiki/Bell_Telephone_LaboratoriesBell Telephone Laboratories, the laser was called an

optical maser; This term is now old-fashioned and hardly used. Fig (6.1). optical maser Wavelengths of commercially available lasers. Laser types

with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The height of the

lines and bars gives an indication of the maximal power/pulse energy commercially available, while the color codifies the type of laser material (see

the figure description for details). Most of the data comes from Weber's book Handbook of laser wavelengths, with newer data in particular for the

semiconductor lasers. Gas laser is a http://en.wikipedia.org/wiki/Laserlaser which functions when an http://en.wikipedia.org/wiki/Electric

currentelectric current is discharged through a http://en.wikipedia.org/wiki/Gasgas to produce coherent light. The earliest type of laser, the gas

laser, was the first continuous-light laser and the first laser to function on the physics principle of converting electrical energy to a laser light

output. Helium was the first gas to inter the laser technology. The first gas laser, the http://en.wikipedia.org/wiki/Helium%E2%80%93neon_laserHelium

neon laser (HeNe), was invented by joined research by the Iranian physicist http://en.wikipedia.org/wiki/Ali_JavanAli Javan and American physicist

http://en.wikipedia.org/wiki/William_R._Bennett,_Jr.William R. Bennett, Jr. in 1960. The output of their co-operation produced a coherent light beam

in the infrared area of the spectrum at 1.15 micrometre.6.2-Types of gas laser The gas lasers which convert electrical energy to a laser light output

use many gases for many purposes. The first to introduce is the Helium-neon or http://en.wikipedia.org/wiki/HeNeHeNe laser which can be made to

vibrate at over 160 different wavelengths when the cavity Q is adjusted to its maximum at the desired wavelength. This can be done by adjusting

spectral response of the mirrors or by using a dispersive element (http://en.wikipedia.org/wiki/Littrow_prismLittrow prism) in the cavity. Units

operating at 633ÿnm are very common in Schools and laboratories employ units which operate at 633 nm because of their low cost and they are

perfect in their beam qualities. Another gas is http://en.wikipedia.org/wiki/Carbon_dioxidecarbon dioxide, or CO2 lasers which can emit hundreds of

kilowatts at 9.6 http://en.wikipedia.org/wiki/%CE%9Cmæm and 10.6ÿæm, and are often used in industry for cutting and welding. The efficiency of this

kind of a CO2 laser is over 10%. http://en.wikipedia.org/wiki/Carbon_MonoxideCarbon Monoxide or "CO" lasers have the potential for very large outputs

however, the use of this type of laser is limited because Carbon Monoxide is highly poisonous gas. The persons operating this kind of gas laser

protect themselves from this fatal gas and it is extremely corrosive to many materials included seals, gaskets, etc. Therefore, extreme care must be

used when building and using CO lasers. An additional type of gas laser, http://en.wikipedia.org/wiki/Ion_laserArgon-ion lasers, which emit light in

the range 351-528.7ÿnm. Depending on The various types of optics and the laser tube produce a different number of lines which is usable but the most

commonly used lines are 458ÿnm, 488ÿnm and 514.5ÿnm. Nitrogen which is a cheep gas is used in the laser technology by http://en.wikipedia.org/wiki

TEA_lasertransversing electrical discharge in gas at atmospheric pressure (TEA) producing UV light at 337.1ÿnm. http://en.wikipedia.org/wiki

CopperCopper laser ( more specifically, copper vapor, and copper bromide vapor), with two spectral lines of green (510.6 nm) and

is considered as the most powerful laser which has the highest efficiency in the visible spectrum. Metal ion lasers are another type of gas

that typically produce http://en.wikipedia.org/wiki/Ultravioletultraviolet wavelengths. http://en.wikipedia.org/wiki/HeliumHelium-http://en.wikipedia

org/wiki/SilverSilver (HeAg) 224ÿnm http://en.wikipedia.org/wiki/NeonNeon-http://en.wikipedia.org/wiki/CopperCopper (NeCu) 248ÿnm and http://en

wikipedia.org/wiki/HeliumHelium-http://en.wikipedia.org/wiki/CadmiumCadmium (HeCd) 325ÿnm are three examples. These lasers have particularly narrow

oscillation http://en.wikipedia.org/wiki/Linewidthline widths of less than 3 http://en.wikipedia.org/wiki/GHzGHz (0.5 http://en.wikipedia.org/wiki

Picometerspicometers), making them possible candidates for use in http://en.wikipedia.org/wiki/Fluorescencefluorescence suppressed http://en

wikipedia.org/wiki/Raman_spectroscopyRaman spectroscopy.Here Are the AdvantagesHigh volume of http://en.wikipedia.org/wiki/Active_laser_mediumactive

materialActive material is relatively inexpensiveAlmost impossible to damage the active materialHeat can be removed quickly from the http://en

wikipedia.org/wiki/Optical_cavitycavityThe ApplicationsHe-Ne laser is mainly used in making holograms.In laser printing He-Ne laser is used as a

source for writing on the photosensitive material.He-Ne lasers were used in reading the Bar Code which is imprinted on the product. They have been

largely replaced by http://en.wikipedia.org/wiki/Laser_diodeslaser diodes.Nitrogen lasers and excimer laser are used in pulsed dye laser pumping.Ion

lasers, mostly argon, are used in CW dye laser pumping.Table (6.1) : Laser Type6.3-Gas LasersTypes of gas lasers are used in holograms In the field

of holography, there are two types of laser in order to produce holograms: these are the continuous wave laser and the pulsed laser. The first, the

continuous wave laser, emits a continuous stream of laser light, the other type, the pulsed laser, emits laser light in bursts. Continuous wave

lasers are preferred to the other type and more commonly used in standard holography. It was said earlier that the recording of an interference

pattern on the film forms a hologram. Holograms formed in this way could risk being dim or not visible at all if the subject moved even a microscopic

amount, from one moment to the next, because two different interference patterns would be recorded. This defect could be overcome by an exposure with

a continuous wave laser which can take from less than a second to several minutes. During this time there can be no motion at all, including pulses

coming from the ground; therefore, the laser, optics, and subject must be placed on a table which isolates vibration. For the system to work at all

no movement whatsoever should be emitted from the objects being photographed at all. Or as the writer sarcastically puts it " subjects that

holographed with continuous wave lasers must be `dead' or immobile objects that can be bolted or glued to the optical table surface". Pulsed lasers

quite the opposite of continuous wave lasers, pulsed lasers emit extremely quick bursts of very powerful laser light. Exposures can be made in

nanoseconds' (billionths of a second). Vibration tables are not needed and holograms can be made of all kinds of objects including people, animals

or even splashing water because no significant movement takes place in a nanosecond in no time. However, pulsed lasers are not used more because they

are significantly more expensive than the typical continuous wave laser.6.4-RGB color model The RGB color model is an http://en.wikipedia.org/wiki

Additive_coloradditive http://en.wikipedia.org/wiki/Color_modelcolor model in which http://en.wikipedia.org/wiki/Redred, http://en.wikipedia.org/wiki

Greengreen, and http://en.wikipedia.org/wiki/Blueblue light are added and mixed together in various ways to reproduce a broad array of an out of http

en.wikipedia.org/wiki/Colorcolors. The name of the process, RGB, comes from the initial letters of the three http://en.wikipedia.org/wiki/Additive

primariesadditive primary colors, R from red, G from green, and B from blue. The RGB color system has a main purpose which is for the sensing

representation, and display of images in electronic systems, for example, televisions and computers, in addition to its use in traditional http://en

wikipedia.org/wiki/Photographyphotography. Before the electronic age, the RGB color model was based on the way human beings perceive colors. RGB is a

device-dependent color model which consists of different devices which sense or reproduce a certain RGB value in a different form, since the color

elements (such as phosphors or dyes) and their response to the individual R, G, and B levels differ from one manufacturer to another, or even in the

same device as time changes. If an RGB value to define the same color across devices there must be some kind of http://en.wikipedia.org/wiki/Color

managementcolor management. The typical RGB input devices are color http://en.wikipedia.org/wiki/Professional_video_cameraTV and video cameras, http

en.wikipedia.org/wiki/Image_scannerimage scanners, and http://en.wikipedia.org/wiki/Digital_cameradigital cameras. Typical RGB output devices are TV

sets of different technologies (http://en.wikipedia.org/wiki/Cathode_ray_tubeCRT, http://en.wikipedia.org/wiki/Liquid_crystal_display_televisionLCD

http://en.wikipedia.org/wiki/Plasma_displayplasma, etc.), http://en.wikipedia.org/wiki/Computer_displaycomputer and http://en.wikipedia.org/wiki

Mobile_phonemobile phone displays, http://en.wikipedia.org/wiki/Video_projectorvideo projectors, multicolor http://en.wikipedia.org/wiki/LEDLED

displays, and large screens such as http://en.wikipedia.org/wiki/JumboTronJumboTron, etc. Color printers. On the other hand, there are devices which

are not RGB, but http://en.wikipedia.org/wiki/Subtractive_colorsubtractive color devices (typically the http://en.wikipedia.org/wiki/CMYK_color

modelCMYK color model). The present article deals with concepts common to all the different color spaces that use the RGB color model, and ones which

are used in various types of implementation in color image-producing technology.6.5-Additive Primary Colors How is a color formed with RGB? Here

three colored light beams (one red, one green, and one blue) must be superimposed (for example by having them emitted from a black screen, or by

reflection from a white screen). Each of the three beams is called a component of that color, and each of them may have various arbitrary intensities

from fully off to fully on, in the output mixture .The RGB color model is additive. This can be illustrated as follows: the three light beams are

added simultaneously, and their light spectra add, wavelength for wavelength, to make the final color's spectrum.Fig (6.2). RGB Various intensities

produce different colors: Zero intensity for each component gives the darkest color (no light, considered the black), and full intensity of

gives a http://en.wikipedia.org/wiki/Whitewhite; the quality of this white depends on the nature of the primary light sources, but if they are

properly balanced, the result is a neutral white matching the system's http://en.wikipedia.org/wiki/White_pointwhite point. When the intensities for

all the components are the same, the output is a shade of gray, darker or lighter naturally depends on the intensity. When the intensities are

different, the result is a colorized http://en.wikipedia.org/wiki/Huehue, more or less http://en.wikipedia.org/wiki/Saturation_%28color_theory

saturated depending on the difference of the strongest and weakest of the intensities of the primary colors being employed. Primary and secondary

colors are a direct result of the strength of intensity: when one of the components has the strongest intensity, the color is a hue near this primary

color (reddish, greenish, or bluish), and when two components have the same strongest intensity, then the color is a hue of a secondary color (a

shade of http://en.wikipedia.org/wiki/Cyancyan, http://en.wikipedia.org/wiki/Magentamagenta or http://en.wikipedia.org/wiki/Yellowyellow). A

secondary color is formed by the sum of two primary colors of equal intensity: cyan is the result of green+blue, while magenta is red+blue, and

yellow is red+green. Every secondary color is the complement of one primary color; when a primary and its complementary secondary color are added

together, the result is white: cyan complements red, magenta complements green, and yellow complements blue, To put it differently, primary and

secondary colors are in a complementarity relationship. The RGB http://en.wikipedia.org/wiki/Color_modelcolor model itself does not define what is

meant by red, green, and blue colorimetrically, and so the results of mixing them are not specified as absolute, but relative to, and based on

primary colors. When the exact http://en.wikipedia.org/wiki/Chromaticitychromaticities of the red, green, and blue primaries are specified and

isolated, the color model then becomes an http://en.wikipedia.org/wiki/Absolute_color_spaceabsolute color space, such as http://en.wikipedia.org/wiki

SRGB_color_spaceRGBs or http://en.wikipedia.org/wiki/Adobe_RGB_color_spaceAdobe RGB; (For more information, see http://en.wikipedia.org/wiki/RGB

color_spacesRGB color spaces for more details).6.6-Physical principles for the choice of red, green, and blueFig (6.3). Physical principles An RGB

laser is a kind of laser that emits a single beam of light, but consisting of three beams combined together: red (R), green (G) and blue (B)

are prime colors and by mixing them in the correct proportions it's possible to get any other color one wishes to get. By simply mixing these three

colors (without adjusting the brightness, just turn on or off a component) the following colors can be obtained: red (R), green (G), blue (B), yellow

R+G), magenta (R+B), cyan (B+G), white (R+G+B), and that are possible colors of light emitted by my RGB laser described here. There are also other

RGB lasers which are based on a single Ar-Kr gas laser that manipulates different spectral lines and emits white light. That white beam goes through

switched color filters to obtain different beam colors. However, nowadays RGB lasers are made of three separate lasers and three laser beams are

combined to one white beam. Dichroic filters are used for beam combining. Then, to obtain any color you just need to adjust the power of each laser

R, G and B laser), and that is quite simple in case of diode lasers. This is exactly how my laser is made, below you can see a diagram showing three

lasers and beam combining optics.6.7-Dichroic filter A dichroic filter is defined as a thin-film filter, or http://en.wikipedia.org/wiki

Interference_filterinterference filter which is a highly accurate http://en.wikipedia.org/wiki/Colorcolor http://en.wikipedia.org/wiki/Filter

optics%29filter used to selectively pass http://en.wikipedia.org/wiki/Lightlight of a small range of colors at the same time http://en.wikipedia.org

wiki/Reflection_%28physics%29reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color(s

of light that they reflect, rather than the color(s) they pass. (See http://en.wikipedia.org/wiki/Dichroismdichroism for the etymology of the term

To sum up, dichroic filters either pass or reflect colors of light. Used before a light source, a dichroic filter produces light that is http://en

wikipedia.org/wiki/Perceptionperceived by humans to be highly http://en.wikipedia.org/wiki/Saturation_%28color_theory%29saturated (intense) in color

Even though dichroic filters are very expensive, such filters are commonly used for http://en.wikipedia.org/wiki/Architecturearchitectural http://en

wikipedia.org/wiki/Dichroic_filter[1] and http://en.wikipedia.org/wiki/Stage_lightingtheatrical purposes.Fig (6.4). Dichroic filterFig

Dichroic filter experimentRed2x 650nm 200mW diode from LPC-815 DVD-RW sledGreen532nm 100mW DPSS moduleBlue405nm 115mW diode from PHR-803T HD DVD

sledor 488nm 80mW argon laserTotal output powerabout 500mWScannersGSI G100PD closed-loop galvos with GSI amplifierDichrosdisassembled from broken

computer equipmentDACPopelscanTable (6.2). details6.8-The Laser inside the Projector Fig (6.6): Optical Table of Typical Laser Projector The

application for the laser projectors is in the entertainment industry. Most high-end laser projectors are custom-built and some functions are

incorporated according to the type of effect that is required. Figure 1 shows the optical function diagram of typical laser projector. It seems

made laser projectors have only X-Y scanner which can be used for the most generic effects. In this project, I chose only an X-Y scanner and aimed to

project exact laser graphics and animations as a goal.6.9-Blanking/Modulator The blanking mechanism is a modulator which gets red of an unnecessary

laser beam by interrupting it. Most gas lasers require this mechanism in front of laser output window because the gas laser the output power quickly

A galvanometer is used for the blanking mechanism as its actuator to move the interrupter. For multi-colored system, such as mixed-gas laser, an

optical modulator, called PCAOM, is used to control each color line. The mechanical blanking other than safety shutter is often omitted on the laser

projector using PCAOM or solid state lasers which can be modulated directly.6.10-Beam switcher/Effector The beam switcher is another mechanism that

feeds a laser beam to the selected effector, and the effector interrupts a laser beam with any optical filter. Switching speed and accuracy are

particularly required, therefore the open-loop galvos, stepping motors and solenoids are used to move the optics. The optical filter used for the

effector is to spread or diffuse the laser beam. Some grating disks are often used to obtain such an effect. The laser beam passed through the

effector creates splashed beams as beam effect, and an abstract pattern as screen effect