1001uses for laser

Imagine a narrow, one-way, coherent, moving, amplified beam of light, fired by excited atoms, powerful enough to slice through steel, carry television transmissions and detect 40 year old fingerprints. In 1917, Einstein speculated that under certain conditions atoms could absorb light and be stimulated to shed their borrowed energy. Charles Townes conceived of the laser (light amplification by stimulated radiation) in 1951. In 1960, Theodore Maiman invested the glare of a flash lamp in a rod of synthetic ruby, creating the first human-made laser. The laser involves exciting atoms and passing them through a medium such as crystal, gas, or liquid. As the cascade of photon energy sweeps through the medium, bouncing off mirrors, it is reflected back and forth, gains energy, and emerges as a high wattage beam of light. Little did the inventors realize how the laser would come to affect nearly every product, service, and profession. Lasers are used by professions as diverse as agronomy and photography to manufacturing and meteorology.

However, some of the most revolutionary advancements in laser technology have been through their use in medicine. Lasers can currently be found in the fields of dermatology, gynecology, cardiology, ontolaryncology, urology, dentistry, back care, oncology, and opthalmology. As a surgical tool the laser is capable of three functions. When focused on a point it can cut deeply, cauterizing as it cuts, reducing the surgical trauma caused by a knife. It can scan tissue, vaporizing the surface which it scans. Or, through optical fibers, it can permit a surgeon to see inside the body.

Skin Deep

Laser's earliest medical applications were in the field of dermatology. Impressively, in the treatment of skin problems, the laser causes little discomfort, carries no risk of infection, and produces no scarring. In 1986, the FDA approved dye lasers for use in the treatment of birthmarks. Firing a laser at a port-wine stain causes the dense network of blood vessels to close&emdash;photocoagulation&emdash;thereby reducing redness. Dramatic results have been seen in the treatment of infants.

In addition, lasers effectively bleach the dyes in unwanted tatoos, fade the pigments in age spots and moles, can reduce wrinkles, and help heal skin ulcer wounds. Dermatologists feel lasers may eventually be valuable in the treatment of varicose veins and skin cancer.

For Women Only

Lasers have also been used extensively in the field of gynecology. Again, the laser is faster, less invasive, reduces infection risks, and allows for a quicker recovery. Lasers have been used to treat ectopic pregnancies, dysmenorrhea, ovarian cysts, and endometriosis by vaporizing diseased or excess tissue. Lasers have also been used to perform hysterectomies, and to reconstruct damaged or blocked Fallopian tubes, allowing infertile women to conceive.

Additionally, lasers have aided in the screening and early detection of cervical cancer, which is nearly always curable in its early stages. Fluorescent-dyed tissue samples, when struck by laser light reveals quantities of normal and abnormal cells, leading specialists to diagnose cancer's presence and stage.

Have a Heart

In the field of cardiology, lasers have not perfomed as well as hoped. Lasers were hailed as an alternative to angioplasty. Doctors hoped that lasers could be threaded into arteries with a catheter to blast away calcium plaque build-up. In fact, some patients were operated on successfully. However, the procedure risks creating dangerous blood clots or puncturing an artery. Furthermore, catheters proved too stiff to pass through the body's convoluted blood vessels. Further research may still find the laser valuable in heart surgery.

Ear, Nose and Throat

Ontolaryncology has seen several practical advantages to the laser rather than a scalpel. In larynx surgery, any damage to the voice box can severely impair speech. The laser is able to vaporize lesions without additional damage to the larynx. Lasers have also been successful in treating snoring by trimming away part of a persons' uvula. Lasers have restored some people's hearing by effectively vaporizing defective, hardened or locked stape bones in the ear. And lasers have a 90% success rate in treating chronic rhinitis&emdash;persistent congestion and running nose. Applied to the surface of the swelled tissues in the nose, the laser creates scar tissue that acts to prevent future swelling. Lasers have also been used to remove nasal polyps and tumors, and to treat chronic nosebleeds by sealing off blood vessels.

For Men Only

While the laser has not gained widespread acceptance in urology, it appears that they soon will. Lasers have been used for years to treat early-stage bladder cancer. Advancements have also been in using lasers to treat enlargement of the prostate. A Nd-YAG laser is used to remove tissue. Over 100,000 laser prostate operations are done each year. Within five years, over 60% of the prostate surgery will be done using lasers. Doctors feel that lasers may also be valuable in reversing vasectomies by welding the gap that is cut during a vasectomy.

Open Your Mouth

While not widely used, lasers may make visits to the dentist more pleasant for patients. Experimental uses hold hope for the future. Lasers have been used to clean out root canals, in surgery for TMJ jaw disease, in the vaporizing of plaque and the cleaning of teeth, in melting dental filling material, and in 3-dimensional imaging to record minute changes by orthodontists checking for misaligned teeth or the effects of braces upon teeth.

My Aching Back

Patients suffering from herniated disks, and unable to recover using physical therapy, can now be treated with lasers. Over 500,000 Americans undergo back surgery each year. Lasers can be used to vaporize tissue in a disk, creating a vacuum. This causes the disk to shrink away from the pressed nerve, relieving pain. Such surgery eliminates the need for cutting, scarring, hospitalization, postoperative instability, immobility, and the need for general anesthesia. The cost is only $6,000&emdash;one third of traditional disk surgery.

Cancer Fighter

In addition to the laser's use in detecting cervical cancer, lasers have been used as probes, aiding in the imaging and detection of tumors. A new laser probe allows surgeons to see layers of tissue beneath and around the scalpel without having to make a wide, destructive incision. By inserting the probe into an incision as small as 3 mm, surgeons are able to see instant pictures of a patient's anatomy as the surgeon is operating, resulting in direct, immediate evidence of his or her progress in vaporizing a tumor.

Lasers also hold a promising role in the treatment of certain types of cancer. In experiments, HPD (hematoporhyrin derivative), a laser sensitive dye, is injected into the body and absorbed by all the body's cells. The HPD remains in malignant cells. Activated by a laser, the HPD can be used to dissolve the malignant cells, eliminating the need for radiation treatment and chemotherapy.

The Eyes Have It

No field has seen greater accomplishments with lasers as opthalmology. The advantage in this field is that the laser beam can enter the eye without injuring it. Lasers have been successfully used for photocoagulation to seal leaking blood vessels, repair retinal hemorrhages, or weld detached retinas. Through iridectomy, lasers can relieve the fluid build up of glaucoma. In photodisruption, lasers remove tissue, allowing the insertion of an artificial lens behind the iris. With photoradiation and photovaporization, the laser is used as a bloodless scalpel to destroy eye tumors. In cases of diabetic retinopathy (degeneration of the retina), lasers have prevented blindness by destroying excess blood vessels on the retina's surface. Lasers can also correct scars and remove calcium deposits on the eye.

Just last year, the FDA approved the use of Summit Technology's blue-light, diode excimer laser for the treatment of nearsightedness, which affects over 60 million Americans. During the 20 minute bloodless procedure, a cold laser is fired at the cornea, shaving and reshaping it to provide 20:40 vision. Called photorefractive keratectomy (PRK), the procedure has been done on over 250,000 patients so far and will soon be commercially available for $1,500 per eye. Doctors hope that PRK may lead to similar procedures to replace corneal transplant surgery, and to correct astigmatism and congenital farsightedness.

These procedures represent just the beginning. Ongoing research shows additional medical uses for the laser, including laser accupuncture, laser induced fluorescence to detect chemicals in blood, endoscopic gastrointestinal treatment, the treatment of the affected limbs of cerebral palsy patients, and a cold laser that reduces the swelling and onset of carpal tunnel.

Lasers have come a long way since their creation in the 1960s. They are a prime example of how the movement of an idea can truly change the world. While they are not a medical cure-all, there have been major medical advancements because of them. Hurdles remain. Many procedures await FDA approval. Some doctors are reluctant to use new, unfamiliar tools. And, the equipment cost remains high. For many patients, however, lasers are a promising tool that offers much hope. According to a Liquid Vision developer, "Laser advancements in the 1990's will rival computer advancements of the 1980's."

Optics

Optics (ὀπτική appearance or look in Ancient Greek) is the science that describes the behavior and properties of light and the interaction of light with matter. Optics explains optical phenomena.

The field of optics usually describes the behavior of visible, infrared, and ultraviolet light; however because light is an electromagnetic wave, similar phenomena occur in X-rays, microwaves, radio waves, and other forms of electromagnetic radiation and analogous phenomena occur with charged particle beams. Optics can largely be regarded as a sub-field of electromagnetism. Some optical phenomena depend on the quantum nature of light relating some areas of optics to quantum mechanics. In practice, the vast majority of optical phenomena can be accounted for using the electromagnetic description of light, as described by Maxwell's Equations.

The field of optics has its own identity, societies, and conferences. The pure science aspects of the field are often called optical science or optical physics. Applied optical sciences are often called optical engineering. Applications of optical engineering related specifically to illumination systems are called illumination engineering. Each of these disciplines tends to be quite different in its applications, technical skills, focus, and professional affiliations. More recent innovations in optical engineering are often categorized as photonics or optoelectronics. The boundaries between these fields and "optics" are often unclear, and the terms are used differently in different parts of the world and in different areas of industry.

Because of the wide application of the science of "light" to real-world applications, the areas of optical science and optical engineering tend to be very cross-disciplinary. Optical science is a part of many related disciplines including electrical engineering, physics, psychology, medicine (particularly ophthalmology and optometry), and others. Additionally, the most complete description of optical behavior, as known to physics, is unnecessarily complicated for most problems, so particular simplified models are used. These limited models adequately describe subsets of optical phenomena while ignoring behavior irrelevant and/or undetectable to the system of interest.

Classical optics

Before quantum optics became important, optics consisted mainly of the application of classical electromagnetism and its high frequency approximations to light. Classical optics divides into two main branches: geometric optics and physical optics.

Geometric optics, or ray optics, describes light propagation in terms of "rays". Rays are bent at the interface between two dissimilar media, and may be curved in a medium in which the refractive index is a function of position. The "ray" in geometric optics is an abstract object which is perpendicular to the wavefronts of the actual optical waves. Geometric optics provides rules for propagating these rays through an optical system, which indicates how the actual wavefront will propagate. Note that this is a significant simplification of optics, and fails to account for many important optical effects such as diffraction and polarization.

Geometric optics is often simplified even further by making the paraxial approximation, or "small angle approximation." The mathematical behavior then becomes linear, allowing optical components and systems to be described by simple matrices. This leads to the techniques of Gaussian optics and paraxial raytracing, which are used to find first-order properties of optical systems, such as approximate image and object positions and magnifications. Gaussian beam propagation is an expansion of paraxial optics that provides a more accurate model of coherent radiation like laser beams. While still using the paraxial approximation, this technique partially accounts for diffraction, allowing accurate calculations of the rate at which a laser beam expands with distance, and the minimum size to which the beam can be focused. Gaussian beam propagation thus bridges the gap between geometric and physical optics.

Physical optics or wave optics builds on Huygen's principle and models the propagation of complex wavefronts through optical systems, including both the amplitude and the phase of the wave. This technique, which is usually applied numerically on a computer, can account for diffraction, interference, and polarization effects, as well as aberrations and other complex effects. Approximations are still generally used, however, so this is not a full electromagnetic wave theory model of the propagation of light. Such a full model would (at present) be too computationally demanding to be useful for most problems, although some small-scale problems can be analyzed using complete wave models.

 Topics related to classical optics

Conceptual animation of light dispersion in a prism.

• Aberrations
• Coherence
• Diffraction
• Dispersion
• Distortion
• Fabrication and testing (optical components)
• Fermat's principle
• Fourier optics
• Geometric optics of:
  • Lenses
  • Mirrors
  • Optical instruments
  • Prisms
• Gradient index optics
• Interferometry
• Optical lens design
• Optical resolution
• Polarization
• Ray (optics)
• Ray tracing
• Reflection
• Refraction
• Scattering
• Spectrum
• Wave

Modern optics

Modern optics encompasses the areas of optical science and engineering that became popular in the 20th century. These areas of optical science typically relate to the electromagnetic or quantum properties of light but do include other topics.

Topics related to modern optics

• Adaptive optics
• Circular dichroism
• Crystal optics
• Diffractive optics
• Fiber optics
• Waveguide (optics)
• Holography
• Integrated optics
• Jones calculus
• Lasers
• Lens flare
• Microlens
• Non-imaging optics
• Nonlinear optics
• Optical pattern recognition
• Optical processors
• Optical vortex
• Photometry
• Photonics
• Quantum optics
• Radiometry
• Statistical optics
• Thin-film optics
• X-ray optics

 Other optical fields

• Abbe number
• Color science
• Image processing
• Information theory
• Lighting
• Machine vision
• Optical communication
• Optical computers
• Optical data storage
• Optical feedback
• Pattern recognition
• Photography (science of)
• Radiative heat transfer
• Thermal physics
• Visual system

 Everyday optics

Optics is part of everyday life. Rainbows and mirages are examples of optical phenomena. Many people benefit from eyeglasses or contact lenses, and optics are used in many consumer goods including cameras. Superimposition of periodic structures, for example transparent tissues with a grid structure, produces shapes known as moiré patterns.

لیزر

Two European scientists won the 2007 Nobel Prize in physics on Tuesday for a discovery that lets computers, iPods and other digital devices store reams of data on ever-shrinking hard disks.
France's Albert Fert and German Peter Gruenberg independently discovered a physical effect in 1988 that has led to sensitive tools for reading the information stored on hard disks. That sensitivity lets the electronics industry use smaller and smaller disks.
"The MP3 and iPod industry would not have existed without this discovery," Borje Johansson, a member of the Royal Swedish Academy of Sciences told The Associated Press. "You would not have an iPod without this effect."
The two scientists discovered a phenomenon called giant magnetoresistance. In this effect, very weak changes in magnetism generate larger changes in electrical resistance. This is how information stored magnetically on a hard disk can be converted to electrical signals that the computer reads.
Smaller disks mean fainter magnetic signals, so the ability to detect them is key to shrinking hard disks.
The first disk-reading device based on the effect was launched in 1997 "and this soon became the standard technology," the Nobel committee said.
Phil Schewe, a physicist and spokesman for the American Institute of Physics, said the prize honored "a terrific combination of great physics and huge practical application.
"I can hardly think of an application that has a bigger bang than the magnetic hard drive industry. Every one of us probably owns three or four or five devices, probably more, that depend on billions of bits of information stored on something the size of a dime."
Fert, 69, is the scientific director of the Mixed Unit for Physics at CNRS/Thales in Orsay, France, while Gruenberg, 68, is a professor at the Institute of Solid State Research in the west German city of Juelich.
Asked if he'd thought his discovery would have such wide application, Fert told The Associated Press, "You can never predict in physics.... These days when I go to my grocer and see him type on a computer, I say "'Wow, he's using something I put together in my mind. It's wonderful.'"
In a telephone conference with the award committee, Fert said he was very happy to win, and to share the $1.5 million prize with Gruenberg.
"This is a surprise for me but I knew that it was possible," he said. "I knew I was among the many candidates."
A former rugby player and now avid sailboarder, Fert told France's Inter Radio that he planned to share some of the spoils of his winnings with colleagues.
"As usual when I get prizes, I share a little with my associates and then I will see," he said. "I don't know. I think I need new sails for my windsurfers."
Last year, Americans John C. Mather and George F. Smoot won the physics prize for their work examining the infancy of the universe, studies that have aided the understanding of galaxies and stars and increasing support for the Big Bang theory of the beginning of the universe.
On Monday, two American scientists, Mario R. Capecchi and Oliver Smithies, and Briton Sir Martin J. Evans, won the 2007 Nobel Prize in medicine for groundbreaking discoveries that led to a powerful technique for manipulating mouse genes.
Prizes for chemistry, literature, peace and economics will be announced through Oct. 15.
The peace award is announced in Oslo, while the other prizes are announced in Stockholm. The prizes, each of which carries a cash prize of $1.5 million, were established in the will of Swedish industrialist Alfred Nobel.
The Nobel prizes are always presented to the winners on the Dec. 10 anniversary of the death of its creator.

منبع : http://www.nobelprize.org

آلبر فر، فيزيكدان فرانسوي در سال 1938 در كاركاسون متولد شده است. او نيز هم زمان با گرونبرگ در سال 1988 در دانشگاه پاريس - جنوب در اورسي به شيوه ديگري پديده اثر مقاومت بزرگ مغناطيسي GMRرا كشف كرد.
استفاده از اين پديده اين امكان را فراهم مي آورد كه داده هايي كه به صورت مغناطيسي در ديسك هاي سخت CD ذخيره شده اند به سيگنال هايي الكتريكي تبديل شوند كه براي رايانه ها قابل پردازش و فهم باشند.
به اين ترتيب امكان توليد قطعات مينياتوري در دستگاه هاي الكترونيكي و رايانه اي فراهم آمد كه حاصل آن دستگاه هايي مانند رايانه هاي همراه و يا «آي پاد» iPod است.
پتر گرونبرگ در زماني برنده جايزه فيزيك نوبل مي شود كه در دوران بازنشستگي خود به سر مي برد اما آلبر فر همچنان در دانشگاه پاريس - جنوب تدريس مي كند.

پروفسور حسابي

سيد محمود حسابي در سال 1281 (ه.ش), از پدر و مادري تفرشي در تهران زاده شدند. پس از سپري نمودن چهار سال از دوران كودكي در تهران, به همراه خانواده (پدر, مادر, برادر) عازم شامات گرديدند. در هفت سالگي تحصيلات ابتدايي خود را در بيروت, با تنگدستي و مرارت هاي دور از وطن در مدرسه كشيش هاي فرانسوي آغاز كردند و همزمان, توسط مادر فداكار, متدين و فاضله خود (خانم گوهرشاد حسابي) , تحت آموزش تعليمات مذهبي و ادبيات فارسي قرار گرفتند.

استاد, قرآن كريم را حفظ و به آن اعتقادي ژرف داشتند. ديوان حافظ را نيز از برداشته و به بوستان و گلستان سعدي, شاهنامه فردوسي, مثنوي مولوي, منشات قائم مقام اشراف كامل داشتند.

شروع تحصيلات متوسطه ايشان مصادف با آغاز جنگ جهاني اول, و تعطيلي مدارس فرانسوي زبان بيروت بود. از اين رو, پس از دو سال تحصيل در منزل براي ادامه به كالج آمريكايي بيروت رفتند و در سن هفده سالگي ليسانس ادبيات, در سن نوزده سالگي, ليسانس بيولوژي و پس از آن مدرك مهندسي راه و ساختمان را اخذ نمودند. در آن زمان با نقشه كشي و راهسازي, به امرار معاش خانواده كمك مي كردند. استاد همچنين در رشته هاي پزشكي, رياضيات و ستاره شناسي به تحصيلات آكادميك پرداختند. شركت راهسازي فرانسوي كه استاد در آن مشغول به كار بودند, به پاس قدرداني از زحماتشان, ايشان را براي ادامه تحصيل به كشور فرانسه اعزام كرد و بدين ترتيب در سال1924 (م) به مدرسه عالي برق پاريس وارد و در سال 1925 (م) فارغ التحصيل شدند.

همزمان با تحصيل در رشته معدن, در راه آهن برقي فرانسه مشغول به كار گرديدند و پس از پايان تحصيل در اين رشته كار خود را در معادن آهن شمال فرانسه و معادن زغال سنگ ايالت "سار" آغاز كردند. سپس به دليل وجود روحيه علمي, به تحصيل و تحقيق, در دانشگاه سوربن, در رشته فيزيك پرداختند و در سال 1927 (م) در سن بيست و پنج سالگي دانشنامه دكتراي فيزيك خود را , با ارائه رساله اي تحت عنوان "حساسيت سلول هاي فتوالكتريك", با درجه عالي دريافت كردند. استاد با شعر و موسيقي سنتي ايران و موسيقي كلاسيك غرب به خوبي آشنايي داشتند وايشان در چند رشته ورزشي موفقيت هايي كسب نمودند كه از آن ميان مي توان به ديپلم نجات غريق در رشته شنا اشاره نمود.

پروفسور حسابي به دليل عشق به ميهن و با وجود امكان ادامه تحقيقات در خارج از كشور به ايران بازگشت و با ايمان و تعهد, به خدمتي خستگي ناپذير پرداخت تا جوانان ايراني را با علوم نوين آشنا سازد.

پايه گذاري علوم نوين و تاسيس دارالمعلمين و دانشسراي عالي, دانشكده هاي فني و علوم دانشگاه تهران, نگارش ده ها كتاب و جزوه و راه اندازي و پايه گذاري فيزيك و مهندسي نوين, ايشان را به نام پدر علم فيزيك و مهندسي نوين ايران در كشور معروف كرد.

حدود هفتاد سال خدمت علمي ايشان در گسترش علوم روز و واژه گزيني علمي در برابر هجوم لغات خارجي و نيز پايه گذاري مراكز آموزشي, پژوهشي, تخصصي, علمي و ..., از جمله اقدامات ارزشمند استاد به شمار مي رود كه براي نمونه به مواردي اشاره مي كنيم:

_ اولين نقشه برداري فني و تخصصي كشور (راه بندرلنگه به بوشهر)

_ اولين راهسازي مدرن و علمي ايران (راه تهران به شمشك)

_ پايه گذاري اولين مدارس عشايري كشور

_ پايه گذاري دارالمعلمين عالي

_ پايه گذاري دانشسراي عالي

_ ساخت اولين راديو در كشور

_ راه اندازي اولين آنتن فرستنده در كشور

_ راه اندازي اولين مركز زلزله شناسي كشور

_ راه اندازي اولين رآكتور اتمي سازمان انرژي اتمي كشور

_ راه اندازي اولين دستگاه راديولوژي در ايران

_ تعيين ساعت ايران

_ پايه گذاري اولين بيمارستان خصوصي در ايران, به نام بيمارستان "گوهرشاد"

_ شركت در پايه گذاري فرهنگستان ايران و ايجاد انجمن زبان فارسي

_تدوين اساسنامه طرح تاسيس دانشگاه تهران

_ پايه گذاري دانشكده فني دانشگاه تهران

_ پايه گذاري دانشكده علوم دانشگاه تهران

_ پايه گذاري شوراي عالي معارف

_ پايه گذاري مركز عدسي سازي اپتيك كاربردي در دانشكده علوم دانشگاه تهران

_ پايه گذاري بخش آكوستيك در دانشگاه و اندازه گيري فواصل گام هاي موسيقي ايراني به روش علمي

_ پايه گذاري و برنامه ريزي آموزش نوين ابتدايي و دبيرستاني

_ پايه گذاري موسسه ژئوفيزيك دانشگاه تهران

_ پايه گذاري مركز تحقيقات اتمي دانشگاه تهران

_ پايه گذاري اولين رصدخانه نوين در ايران

_ پايه گذاري مركز مدرن تعقيب ماهواره ها در شيراز

_ پايه گذاري مركز مخابرات اسدآباد همدان

_ پايه گذاري انجمن موسيقي ايران و مركز پژوهش هاي موسيقي

_ پايه گذاري كميته پژوهشي فضاي ايران

_ ايجاد اولين ايستگاه هواشناسي كشور (در ساختمان دانشسراي عالي در نگارستان دانشگاه تهران)

_ تدوين اساسنامه و تاسيس موسسه ملي ستاندارد

_ تدوين آيين نامه كارخانجات نساجي كشور و رساله چگونگي حمايت دولت در رشد اين صنعت

_ پايه گذاري واحد تحقيقاتي صنعتي سغدايي (پژوهش و صنعت در الكترونيك, فيزيك, فيزيك اپتيك, هوش مصنوعي)

_ راه اندازي اولين آسياب آبي توليد برق (ژنراتور) در كشور

_ ايجاد اولين كارگاه هاي تجربي در علوم كاربردي در ايران

_ ايجاد اولين آزمايشگاه علوم پايه در كشور

منبع :www.hessabi.com