Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by the optical properties
(effective scattering and absorption coefficient). A special Er:YAG device used for blood sampling without any pain is
presented. Our device emitting on 2940 nm has a special function. It can give four energy levels for four types of skin.
At 3000 nm there is an absorption peak in water, and the absorption in tissue is intense and the vaporization is immediate
and superficial without surrounding damages. Additionally, the very short duration of the pulse (a few hundred
microseconds) avoids the phenomenon of thermal diffusion.
To solve some microsurgical procedures in the anterior and posterior chambers using the photo disruptive effect, a
special Nd:YAG nanosecond laser device is presented. The Nd:YAG laser is q-switched (Cr<sup>4+</sup>:YAG). The laser beam is
expanded. After expansion, the laser beam is passed through a circular variable filter which is rotated by a processor,
allowing energy to be set at any value in the range of 0.5-10 mJ. Two infrared LED-phototransistor pairs are used to
position the filter. The laser beam is focused by the objective at 150 microns behind the object plane to avoid the damage
of the Intraocular Lens.
The main component of the free electron laser is the undulator. Besides the numerical computation approach of the
magnetic field generated by the undulator current, the other possibility is the analogic simulation. Such an approach is
more intuitive and also enables a validation of the numerical simulation. The undulator consists of a Huygens wires
stack. In each wire of the stack the current circulates alternatively from a wire to another. The magnetic field
mathematical model for a wire uses operations like multiplications, divisions, radicals, trigonometric functions and
integrations. These operations were simulated by using an harmonic oscilator (using MC1458 amplifiers), analog
multipliers (AD633) and integrators (using MC1458 amplifiers).
Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by optical properties (effective
scattering and absorption coefficient). In 2900 nm range, the effective scattering coefficient is much smaller than the
absorption coefficient. An Er:YAG skin puncher is presented. Thermal action of a laser beam can be described as one of
three types: hyperthermia, coagulation and volatilization, depending on the degree and the duration of tissue heating. We
are interested in the volatilization process that means a loss of material. The various constituents of the tissue disappear
in smoke at above 100<sup>0</sup>C in a relatively short time of around one tenth of a second. At the edges of the volatilization zone
there is a region of coagulation necrosis. In presented case of an Er:YAG laser operating in a free generation mode, the
mechanical effects can result from explosive vaporization. When the exposure time of the laser is lower than the
characteristic time of the thermal diffusion in the tissue, it produces a thermal containment with an accumulation of heat
without diffusion and an explosive vaporization of the target. The Er:YAG laser device has the pulse length of about 160
microseconds and four emitted energy levels. This device is used to punch the skin for blood sampling for different kinds
of analysis. The front panel of the device has four keys to select the desired energy according to the skin type.