a In a laser if there were no mirror at all more photons cou

a) In a laser, if there were no mirror at all, more photons could get out. Why should there be two mirrors, oneof them partially reflecting instead of no mirror at all?

b) List laser properties which are suitable for medical applications. Discuss whyeach property listed above is different from normal light. You can answer this question by listing the laser properties in a table including comparison with normal light.

Solution

a. the process of aligning a laser beam using two adjustable mirrors in such a way that it will reach a specific point in space with a specific angle. Since laser beams are straight lines, this is equivalent to making the beam pass through two consecutive apertures. This purpose will be defeated if we do not use any mirror or usw only one mirror.

b. There are surgical operations that are difficult to perform with the conventional scalpel and that a laser beam might be used instead. Initial trials showed that a finely focused beam from a carbon dioxide gas laser could cut through human tissue easily and neatly. The surgeon could direct the beam from any angle by using a mirror mounted on a movable metal arm.

Several advantages of laser surgery quickly became apparent. First, the light beam is consistent, which means that it gives off the same amount of energy from one second to the next. So as long as the beam is moving along, the cut it makes (the incision) does not vary in depth; whereas when using a scalpel a doctor can accidentally make part of the incision too deep.

A second advantage of the surgical laser is that the hot beam cauterizes, or seals off, the open blood vessels as it moves along. (This works well mainly for small vessels, such as those in the skin. The doctor still has to seal off the larger blood vessels using conventional methods.)

Still another advantage is that the cells in human tissue do not conduct heat very well, so the skin or any other tissue near the laser incision does not get very hot and is not affected by the beam. This advantage of laser surgery is very helpful when a doctor must operate on a tiny area that is surrounded by healthy tissue or organs.

Nomal light energy does not have energy of this magnitude. It is also subject to other properties such as interference hence consistency will not be there.