Explain how the lasers used in

Medical Uses of Lasers Photo by:

Explain how the lasers used in

Remember we calculated the power density intensity of a 50 Watt laser at 0. Back to where you were! The laser beam contribution.? Theoretical laser beams have this property you must have heard of called TEMoo.

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Let us again assume you have obtained a perfect laser with a perfect TEMoo beam. The smallest size you can focus this beam to assume the lens is perfect too is: Therefore to minimize spot size due to laser beam properties diffraction and divergence we want the largest beam diameter and the shortest focal length 2.

Suppose you ask an optics manufacturer to design and then manufacture the best possible lens that man can make for your particular application we are already losing the game because this by itself is not realistic; no one could afford such a lens for industrial applications.

What is it, you ask? In short, the rays of light that impinge on the lens further away from the lens center, come to focus at the other side nearer to the lens. Therefore if our laser beam is 6 mm wide and we use a 6 mm diameter, 6 mm focal length ZeSe meniscus lens not very common!

Note that, in the example, we chose ZnSe as our lens material and meniscus as its shape, good for CO 2. Can you see how nature is fighting us? To reduce spherical aberration a property of lenseswe want the smallest beam diameter and the longest focal length lens. Remember 3 paragraphs ago?

To minimize spot size that comes about from laser properties diffraction, divergence we wanted the largest beam diameter and the shortest focal length. As you see, these two will always fight each other and compromises have to be made.

In addition no man made, affordable lens is perfect and no real laser beam can be a truly perfect TEMoo diffraction limited beamthat is a reality of life.

They maybe called close to perfect but never perfect.! Further down we continue the TEMoo discussion but for now let us reiterate our conclusions: The smallest theoretical diameter is, roughly, wavelength of the beam.

That adds another factor of 5 or more to the spot size diameter. A convenient parameter was defined and is now called M 2 M squared. The size of the beam is M 2 times larger, the divergence is M 2 times worse and so on. M 2 measures how close the actual laser beam is to a theoretical TEMoo beam profile keep on reading!

TEMoo is a property of the beam that is determined by the physical construction of your laser. The designer has to choose some mirrors for the laser, has to choose some length for the laser and has to choose a cross section for his laser beam these chosen boundaries cause diffraction which is bad.

There always has to be a compromise between the above three and output power and then between output power and final price of the product. A theoretical TEMoo beam has a perfect Gaussian profile. For our discussion of the laser beam, the chosen parameters of the laser structure determine the FWHM of the expected perfect TEMoo beam.

Why say all this? Remember that we said a perfect beam sometimes called diffraction limited would focus to the smallest spot size.

If it is not perfect, its M 2 is larger than one 1then it has excess divergence and will focus to a larger size than a perfect beam would.

In our particular case of CO 2 laser, the wavelength is You need large D to focus the beam to smaller spot but large diameter laser beams can not be made to be TEMoo and large diameter lenses are expensive like crazy.

At the same time you need a short focal length lens to make the spot small but very short focal length lenses are difficult, expensive an impractical to manufacture. Depth of Field The above formula lets us calculate the spot size, or the diameter of the laser beam, at the focal point of a given lens.

Let us think of two cones with their apex attached. The question before us is this; If at the focal point of the lens the apex of the two cones the beam is of a given size, how far away from this point is the beam still in good focus i.

How about 1 mm away? How far do we have to go before the spot size increases to micron? What is so special about micron?

You stop and measure how far from the minimum spot size you have moved. This is half the Depth of field the other half is on the other side of the focal point!. Did I lose you?Back to Sam's Laser FAQ Table of Contents.; Back to Diode Lasers Sub-Table of Contents.

Basic Characteristics, Structure, Safety, Common Types Introduction to Diode Lasers and Laser Diodes Note: Throughout this document, we will use the terms 'laser diode' and 'diode laser' somewhat interchangeably although we will tend to use the term 'diode laser' when referring to a complete system or module.

Laser therapy techniques vary based on the procedure. If a tumor is being treated, an endoscope (a thin, lighted, flexible tube) may be used to direct the laser and view tissues inside the body. Lasers For Skin Rejuvenation Best Anti-aging Products For Asian Skin Skin Tag Removal Products Amazon Lasers For Skin Rejuvenation Does Wrinkle Cream Work Skin Tag Removal Washington Dc Best Otc Skin Care Products For Women Over 50 How To Make Anti Aging Cream At .

The electronic data from your computer is used to control a laser beam—and it's the laser that gets the ink on the page, using static electricity in a similar way to a photocopier. How a laser printer works. Lasers found their first use in the s in local grocery stores, in the product scanner.

The next major accomplishment for laser technology was the CD player. Today, uses span from hospitals to battlefields, to electronics, to factories. The First Ruby Laser.

Watch Theodore Maiman explain the first ruby laser..

Explain how the lasers used in

Theodore Maiman invented the world's first laser, known as the "ruby laser" in

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