Welcome to the UCANDO video on lasers.
The word ‘laser’ stands for ‘light amplification by stimulated emission of radiation / device amplifies / intense beam of light as a result of __ being stimulated.
Basically speaking, a laser is a device which generates a coherent electro-magnetic radiation in or near / many different materials / process / occur in many different ways. Lasers may be categorized in the following categories: chemical, gas, liquid, semiconductor, and solid materials. As you will soon see, lasers are used in many different applications.
They are used in communicating devices. These are typically low-powered devices, which / visible light beam / short-range communication requirements. Lasers are used for bar-code scanning, and as reading devices / commonly found on CD records / and compact discs used in computers. Lasers are also used in fiber-optic communication systems as a means of producing the data to be transmitted through the fiber cable. Lasers are also used as measuring devices. These are used to measure distances and velocities / by measuring / the time it takes / to reflect back / object / laser beam / the distance or / velocity / can be measured. Lasers are also commonly being used in medical/surgical procedures. Lasers have been used for everything / marks / to / __ing / the eye / for surgery. High power lasers are used for welding and cutting applications. __ __ __ typically a CO2 gas device / generate / watts of power. CO2 / extremely / safety precautions must be followed when working on these devices.
Before proceeding into the subject of laser theory, you must first be knowledgeable / safety precautions / used / operating or working on any type of laser devices. First: Never look into a laser device when the power is turned on. / low / laser will cause damage / your eyes / Second: Never point a laser beam at anyone. / to a direct laser beam / or / reflection / severe skin burns and eye damage. Third: Never shine a laser beam on a reflective surface unless the surface is designed for this purpose. / is a concentrated form of light energy, / it will reflect / most materials. / レーザーというのは要するに光ですから、何にぶつかっても、たいてい反射します。 Fourth: Always wear / proper / when working on / device / Fifth: Never point the laser beam at flammable or combustible materials. Even / power / can start fires. Sixth: Most laser devices / very high voltages / which can be fatal / always / laser power supplies. Seventh: When building a laser system from a kit, or working on a laser system, / follow the manufacturer’s safety / included / laser data / safety precautions are provided for your protection.
5.21
Now, let’s examine __ laser theory. / earlier, ‘laser’ stands for / stimulated emission / radiation / intense / light energy / several unusual / and useful properties. To start with, laser light energy is monochromatic. A monochromatic light is a light which / just one wavelength / we / use / and / shine / crystal prism. As you can see, as the light passes through / wavelength / depending upon the light source used, __ color __ __ __ __ exiting the crystal prism. / laser / the same crystal prism, the only / laser light beam. Since the laser light beam / single / energy / cannot be separated. As you can see from the simple illustration, the conventional light / rainbow effect / laser beam, on the other hand, is not separated since it only consists of / single wavelength. Laser light is also coherent. This means / all / single wavelength / beam / one another / Since / they / tend to stay together for a much longer distance. Natural light and most artificial light / beam of light / consist of several / which / randomly together. Since the wavelengths are not uniform, they __ tend to diverge / out / as / farther away / source. Because / and coherent, / laser / able to possess a great deal of energy. This / in its concentrated form / for greater distances / proper object, will only spread / between the earth and the moon. When you consider the distance between the earth and the moon, __ __ __ __ miles / To comprehend how / we need to understand exactly how a laser works.
Before proceeding with how a laser device works, we will pause for __ short review / material__ just discussed.
A laser is a device which produces a coherent electro-magnetic radiation in or near the visible part / light spectrum. There are many types / to generate the stimulated emission of radiation / some of these substances / include chemical, gas, liquid, / and solid materials / Lasers are used for communication purposes; scanning and reading data, as measuring devices, for cutting and welding, and for many medical procedures. When working on or using laser devices, always follow all safety precautions. / Never / beam / no matter how small the power output is. / Never point / anyone / low / damage the skin / you should not make it a habit / aiming / at yourself or other people. / do not / aim / reflective / it will reflect off most surfaces. Always wear proper eye protection designed / you are using. Never aim a laser beam at flammable or combustible materials. Always use extreme caution when working on / laser device. Always follow all manufacturer safety precautions when working on or using any laser device. A monochromatic light is a light / consist of a single frequency. A coherent light is a light which / single frequency / all the light energy __ in phase with itself.
This concludes Review No.1. At this time, you should stop the video and complete Section A in your Student Workbook.
10:20
In this part of the video, we will examine how a laser device is able to produce a monochromatic, coherent beam of light energy.
As you learned earlier, a laser produces a stimulated / radiation / process / is what makes the laser energy / different from man-made / natural light sources. Stimulated emission occurs when an atom or molecule absorbs excess energy / until stimulated / external energy source, such as a photon / proper wavelength / or / electron / when / atom / are stimulated, / in __ form of light. This process / stimulated emission / makes / being produced by the laser device different from / by natural or man-made devices. Visible light energy / which / lose excess energy without the need / To better understand how / laser device / let’s first examine / associated energy level.
Here you see a helium atom / neutrons / radiation occurs the same way / as it does / basic / laser materials. Therefore / will apply to / other / laser substances as well. All atoms contain spherical shells / nucleus / exist / orbit around the nucleus. An atom, in its __ state, / contain / uncharged state / as / its nucleus. That is why the helium atom / two electrons / two protons. A certain amount of energy, which is strictly defined by nature, / orbiting shell / energy / orbit. In its lowest / natural / in its ground state. When a precise amount of energy is added to / said be excited / for __ period of milliseconds to microseconds / normal ground state
In 1911 / Danish / N__ B__ / provided / lose / emit / from a higher energy orbit to a lower energy orbit. This theory / upon / by Albert Einstein / atom or molecule / emit / particular / energy source / atom / molecule. This was the birth / stimulated emission.
According to / emit energy / orbiting / to a lower energy orbit. Therefore, / to occur / atom / excited / orbiting / only be accomplished by causing / absorb energy from an external / are photons and electrons / the photon / electro-magnetic radiation / extremely high velocity particle__ / energy waves / high / energy waves / are called photons. The shorter / more / contain / now / absorbs energy.
When / more energy than / normal / orbiting shell / jump to the next / level / said / be excited / electron / quickly / to its normal orbiting shell / does / release / in the form of photon / particle of light / typical / in which the transition / Under normal conditions, the majority of / remain / level / when the atoms becomes excited / source / move / level to the next higher energy level / When it occurs, / called / population inversion / spontaneous emission / higher / lower energy level / laser light begins.
To maintain the stimulated / photon / requires / excited / as you can. / excited / same type of material / enough / together / emission / as the electrons / excited atoms / undergo / to the ground state. When / an interesting phenomenon happens / when / strikes / already excited / of its own / two photons / whereas / two / then continue / strike more / each time / new / struck / new photon / generated / process / is referred to as ‘stimulated emission’. only / same wavelength / therefore / monochromatic / source, is a single frequency.
/ laser / be / coherent since / are in phase / of / stimulated emission. Because / energy / single / much more powerful and intense beam of light energy / incoherent light source / these characteristics / to travel in parallel with one another / means / scatter / over long distances. You have seen a very / into / particles. However / foundation / energy is produced.
At this time we will pause for a short review / discussed.
An electron / at its lowest natural orbit / ground state. By applying a precise amount of energy / orbiting / jump / next higher / shell / happens / in its excited state. The / excited condition for a period of / When / normal orbit / emit / energy / called / photon / the photon / high / energy waves. When a photon strikes / be generated. A photon of a particular wavelength / same wavelength.
This concludes Review No.2. / stop / in your Student Workbook.
In this part of the video, we / systems / how / only / take place. There must be a / pumping / and / optical cavity. / several / available / As long as / achieve / can maintain / population inversion / take place / suitable / medium. Even / energy / emission / orbital / take place, many / more than one / simultaneously operate on / As you / case / CO2 / gas laser. The energy / often referred to as / material / enable / sufficient energy / levels / inversion / optical pumping / optical / means / exciting the atoms / generally / electron pumping / current / gas laser / electron / passes through / gas molecules / in turn / necessary / to / obtain / output / the / part / system / cavity / mirrors / each / back / stimulated / photons / medium / each / number / increase / now / required / basic / examine / typical / laser / begin / ruby / rod / laser / composition / basic / crystal / and / only / purpose / photons / both / polished / parallel / also / both / crystal / one / end / rear / point / total / in other words / generated / within / the rod / the other end / front end / only partially / only / approximately / escape / surface / here you see / typical / notice / surrounded / basically / operation / very similar / today’s / cameras / when / energized / portion / this energy / atoms / as / absorbs / energy / next / this / excited / as / earlier / excited / microseconds / ground / when this happens / then / other / as / travel / collide / which / in turn / more / continues / escape / laser / crystal / fact / pumped / by means of / laser / light / continuous / difficult / need / well / majority / produced / heat /
