KaVo KEY Laser III 1243 User manual

Technician's instructions
KEY Laser III 1243
Always be on the safe side.

Sales:
KaVo Dental GmbH
Bismarckring 39
D-88400 Biberach
Tel. [phone]
Fax [phone]
Manufacturer:
Kaltenbach & Voigt GmbH
Bismarckring 39
D-88400 Biberach
www.kavo.com

Technician's instructions KEY Laser III 1243
Contents
Contents
Contents ............................................................................................................................................................1
1 Overview of functions ....................................................................................................................................3
1.1 Physical basics .........................................................................................................................................3
1.1.1 What does the term laser mean? .....................................................................................................3
1.1.2 What is laser radiation? ....................................................................................................................4
1.1.3 How does laser radiation form? ........................................................................................................8
1.1.4 Processes involved in the creation of laser radiation Excitation of the laser medium ....................11
1.1.5 Laser wavelengths ..........................................................................................................................19
1.2 Optical system ........................................................................................................................................20
1.3 Electrical system ....................................................................................................................................21
1.3.1 Control unit .....................................................................................................................................21
1.3.2 Software /start-up process ..............................................................................................................22
2 Measuring and configuration .......................................................................................................................24
2.1 Control unit service program ..................................................................................................................24
2.1.1 Service mode overview ..................................................................................................................24
2.1.2 Connect service notebook ..............................................................................................................26
2.1.3 Communicating with KEY Laser 1243 ............................................................................................27
2.1.4 Direct communication with the control unit .....................................................................................30
2.1.5 Switch KEY Laser service mode on/off ..........................................................................................36
2.1.6 The service mode main menu ........................................................................................................37
2.1.7 Operating control ............................................................................................................................38
2.1.8 System control/tests .......................................................................................................................46
2.1.9 Commissioning adjustments ...........................................................................................................55
2.1.10 Static data setup ...........................................................................................................................61
2.1.11 Diagnodent service .......................................................................................................................68
2.1.12 Start without security system ........................................................................................................68
2.1.13 Software download .......................................................................................................................69
2.1.14 User mode error messages/causes ..............................................................................................71
2.1.15 Control computer status LEDs ......................................................................................................73
2.2 Optical system ........................................................................................................................................75
2.2.1 General cleaning of optical components ........................................................................................75
2.2.2 Er:YAG crystal ................................................................................................................................76
2.2.3 HR/PR mirror ..................................................................................................................................85
2.2.4 Deflection mirror .............................................................................................................................94
2.2.5 Lens coupling ...............................................................................................................................103
2.2.6 Measure laser hose coupling ........................................................................................................125
2.2.7 Laser angle piece 2060 ................................................................................................................139
2.2.8 Laser Handpiece P 2061 ..............................................................................................................141
2.2.9 Laser handpiece E 2062 ...............................................................................................................143
2.3 Electrical system ..................................................................................................................................146
2.3.1 Removal of supply connection 230 Volt ~ 50/60 Hz .....................................................................146
2.3.2 Install external voltage transformers .............................................................................................151
2.3.3 Adjust the KEY 3 Diagnodent electronics when the distance standard is mounted .....................161
3 Maintenance work on KEY Laser 1243 .....................................................................................................164
3.1 Ignition system .....................................................................................................................................164
3.2 Cooling system .....................................................................................................................................165
3.3 Spray system ........................................................................................................................................166
3.4 Optical system ......................................................................................................................................169
3.5 Laser contraangle handpiece 2060 ......................................................................................................170
3.6 Laser handpiece P 2061 ......................................................................................................................171
3.7 Laser handpiece E 2062 ......................................................................................................................172
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Technician's instructions KEY Laser III 1243
Contents
3.8 Safety devices ......................................................................................................................................173
3.9 Control unit ...........................................................................................................................................174
3.10 Mechanical system .............................................................................................................................175
3.11 KEY Laser complete ...........................................................................................................................176
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
1 Overview of functions
1.1 Physical basics
Note
The physical design is largely the same as the KEY Laser.
1.1.1 What does the term laser mean?
The term "laser“ is actually an acronym of terms describing the basic process in‐
volved in the operation of lasers.
L ight Light
a multiplication by Multiplication by
s timulated stimulated
e mission of Emission of
r adiation Radiation
The designation “KaVo Key Laser“ is derived from the first letters of the company
name and the substances of the laser medium used.
K aVo
E rbium
Y ag
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
1.1.2 What is laser radiation?
Laser radiation is an electromagnetic wave. The electromagnetic wave does not
require a material substrate for propagation.
Thus, its maximum propagation rate of c = 299,792,458 m/s is reached in the va‐
cuum. The other parameter of interest besides the speed of propagation is the
wavelength or frequency of the electromagnetic wave.
The wavelength is of great relevance for medical laser applications. The wavelength
and intensity together determine the effect on biological tissue.
Electromagnetic waves display all the characteristics a wave must possess in phy‐
sics. However, it is also possible to consider an electromagnetic wave as having a
particle character.
Photons are the particles of the electromagnetic wave. From a different point of view,
however, it is also possible to say that the particle has a wave character. This is
termed "wave-particle dualism“.
Depending on whether the wave or particle character is the essential aspect, waves
or particles (photons) are used to describe the physical processes involved in the
generation of laser radiation.
Of course, the desired wavelength can also be generated with other energy sources.
However, the selective radiation produced by a laser is characterised by the follo‐
wing three advantageous, phenomenal and essential properties:
Note
It is true that all of these features can be achieved with conventional individual
energy sources. However, the laser is the only light source that combines all of
these features.
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
Collimation
Laser radiation is strongly collimated, i.e. the light rays are almost parallel. This
means that the laser beam does not increase much in diameter over extended di‐
stances.
Laser
1
① Conventional light source
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
Monochromasia
Laser radiation is monochromatic, i.e. all light wave trains have the same frequency,
energy and wavelength (the wavelength of the Er:YAG laser is 2.94 µm).
2
3
4
5
② Intensity ④Laser light
③ normal light ⑤Wavelength
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
Coherence
Laser radiation is coherent, i.e. all light wave trains are exactly in phase with regard
to both time and space.
6
7
Laser
⑥ spatial coherence ⑦temporal coherence
⑥ Spatial coherence
⑦ Temporal coherence
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
Transverse electromagnetic modes
The local intensity distribution in the beam is of great importance in addition to the
three essential characteristics of laser radiation mentioned above. This intensity
distribution is described by "transverse electromagnetic modes" (TEM).
The KEY Laser operates in multiple modes, i.e. several modes are superimposed
on each other. Multimode is similar in image to the TEM00 type. ①
It is not the purpose of this section to explain the various modes in detail.
1
Note
With the KEY Laser, it is important to achieve even intensity distribution while ad‐
justing the resonator.
Photographic paper or thermal paper can be used to approximately detect and eva‐
luate the intensity distribution in the cross-section of the beam.
1.1.3 How does laser radiation form?
The following prerequisites must exist to produce laser radiation.
The laser medium
To construct a laser, you must first find a substance - the "laser medium" - which
has an induced emission effect that produces sufficient amplification. The laser me‐
dium then represents the “amplifier“. The laser medium is also a determining factor
of the basic wavelength.
Lasers are grouped into solid-state, liquid, gas and semiconductor lasers according
to state of aggregation and type of laser medium. The characteristics of each group
greatly influence the design of the entire laser system.
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
In the KEY Laser, which belongs to the family of solid-state lasers, an yttrium alu‐
minium garnet laced with the rare-earth element erbium (abbreviated Er:YAG) is
used for the therapeutic laser.
A semiconductor laser is used for the pilot laser.
The following lasers are most commonly used in medical applications: Nd:YAG la‐
ser, CO2 laser, argon/krypton ion laser, dye laser, helium/neon laser, gallium
arsenide laser, excimer laser and the Er:YAG laser which is the one used in the KEY
Laser.
In fact, any substances which are able to generate a population inversion (see
Energy levels section) may be used as the laser medium.
1
2
3
① Metal holder ③KaVo pilot laser
② KaVo Er:YAG laser crystal
The optical resonator
To explain how the optical resonator works, we first need to turn our attention briefly
back to electronics.
To generate a specific frequency or wavelength in high frequency technology or
radio technology, you usually need an oscillatory circuit.
This oscillatory circuit may be created by an amplifier ① and a feedback loop ⑥/
③. Feeding back a fraction of output signal 5 into the input of the amplifier ① causes
an oscillatory structure - an oscillatory circuit - to be created.
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
If the energy that is fed to the oscillatory circuit by the amplifier is greater than the
loss in the oscillatory circuit, the signal in the oscillatory circuit greatly increases and,
as a result, so too does the output signal ②.
Theoretically, the output signal would become infinitely large; in reality, although
muffled by losses and absorption effects, the output signal reaches high levels ne‐
vertheless.
The feeding back of the amplifier results in the output signal being independent of
the input signal.
A self-exciting oscillator is thus formed from the fed back amplifier.
The self-excition in a fed back amplifier is created by the existing background noise
of the amplifier ①.
The laser works in much the same way as high frequency or radio technology.
Different components must be used because of the extremely high frequencies that
are obtained. A feedback loop 6/3 (HR and AR mirrors) is used to achieve an ex‐
tremely high total amplification (induced emission) even though the amplifier 1 is
usually weak.
Only the high total amplification can cause the oscillator (amplifier ① and feedback
loop ⑥/⑦) to make the transition to the self-excited state. The laser reaches this
state by itself due to its background noise (spontaneous emission).
This is when the laser becomes active.
The laser's amplifier ①, the laser medium, requires a suitable form of input energy
④ to achieve this.
The energy for this type of laser is supplied by the flashlamp ⑤. The process this
involves is termed “optical pumping“ and will be explained in more detail in a sepa‐
rate section.
A suitable substance must be chosen for the laser medium (see other section) in
order to obtain an effective amplifier in the resonator (induced emission).
An efficient feedback loop must also be implemented. Two mirrors (the HR and AR
mirrors) reflect the light emitted by the laser medium ① back into the laser medium.
This mirror arrangement makes up the optical resonator.
In the case of the KEY Laser, the laser resonator consists of two plane mirrors in a
parallel arrangement.
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
KaVo Er:YAG
653
4
ll/2
2,94 µm
~ 700 - 950 nm
1
6/3
1 2
4
HR PR
2
5
⑥ Totally reflecting mirror (HR) with op‐
tical resonator - feedback. λ = wave‐
length
④Input energy for the amplifier (laser
medium)
③ Partially reflecting mirror (PR) with
optical resonator - feedback.
②Output energy, signal, frequency and
wavelength (KEY Laser 2.94 µm)
① Amplifier/laser medium ⑤Flash lamp/power source
1.1.4 Processes involved in the creation of laser radiation Excitation
of the laser medium
Excitation of the laser medium
Laser activity can only be obtained by population inversion of two energy levels in
the laser medium.
To achieve this population inversion, energy of a suitable form must be applied to
the laser medium.
This may be achieved in various ways depending on the laser process.
The excitation process to be used must be adapted to the laser type in question.
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
The process used for the therapeutic laser employed in the KEY Laser is excitation
by high-intensity light, referred to as optical pumping.
Contrary to this, the semiconductor laser used as the pilot laser in the KEY Laser is
excited directly by electric current.
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
Optical pumping
If the laser medium is exposed to high intensity light, higher energy levels can be
populated by means of absorption. This process is referred to as optical pumping.
The light source used for the KEY Laser is a high-intensity xenon flashlamp.
However, since only wavelengths with the exact energy differential between two
levels contribute to pumping the laser medium, it is very important that you choose
the correct flashlamp (a xenon one for the Er:YAG laser) and flashlamp operating
mode.
Under optimal conditions, the flashlamp should only emit light at the frequency best
suited to pumping the laser medium (Er:YAG) up to the higher energy level.
Since the laser transition uses only a part of the excitation energy, the laser wave‐
length generated (Er:YAG: 2.94 µm) is greater than the optimal pumping wavelength
(approx. 780 nm to 840 nm for Er:YAG).
Figure I shows the theoretical curve of the light energy emitted by the flashlamp in
a specific operating mode as a function of wavelength.
1
2
Picture 1
① Relative light energy ②Wavelength (nm)
Figure II shows the theoretical curve of the absorption coefficient of the Er:YAG laser
medium as a function of wavelength.
3
2
Picture II
② Wavelength (nm) ③Absorption coefficient
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
Energy levels
The beginning of laser activity is reached by spontaneous emission. The process
of induced emission is then the basis for laser amplification.
In order to make use of this process, electrons in an atom (ion, molecule, solid body)
must have been raised from a lower energy level to a higher level. This process
involves a large number of atoms.
However, in order to actually generate a population inversion, the number of atoms
in which the higher energy level is populated must always be greater than the num‐
ber of atoms in which the lower level is populated. Only this can trigger the laser
amplification.
Optical pumping cannot, however, cause a population inversion in a two-level sys‐
tem. Multi-level systems offer different conditions. The KEY Laser uses a 4-level
system.
The figure is a simplified diagram of a 4-level system.
E3
E2
E1
E0
2,94 µm
Er:YAG
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
The 4-level system
First, the upper energy level E3 is reached by optical pumping from base level E0.
Level E3 is very short-lived.
A rapid transition to level E2 - without radiation - follows. Then the laser transition
from the longer lasting level E2 to the shorter lasting level E1 begins.
Due to its short life, this level E1 drops to the base level E0 very rapidly at the onset
of laser activity. An important characteristic of this system is that the changes in
population at the different energy levels occur in a cycle and therefore always end
in the basic state, ready for the next pump cycle.
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Technician's instructions KEY Laser III 1243
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Absorption in the laser medium
Absorption is a transition from a lower energy level (base level EA) to an excited
higher energy level EB. This is caused by a quantum of radiation (photon) from the
pumping energy source which must have exactly the energy differential EB-EA to
allow the transition from energy level EA to EB and absorption of the photon to take
place.
The diagram shows the absorption process.
① The electron is raised to a higher orbit
② Photon with the energy differential EB-EA from the flashlamp or from the adjacent
atom after spontaneous or stimulated emission.
1
2
EB
EA
2
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Technician's instructions KEY Laser III 1243
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Spontaneous emission in the laser medium
Electrons that are now at the excited higher energy level EB have a tendency to
spontaneously return to the base level EA after a very brief lingering period.
This process is termed “spontaneous emission“. During this process, the electron
releases its energy in the form of electromagnetic radiation, i.e. as a photon. This
photon possesses the energy EB-EA.
The figure shows the process of spontaneous emission.
① The electron drops back to a lower orbit
② Photon (laser radiation) with energy differential EB-EA.
1
2
2
EB
EA
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Technician's instructions KEY Laser III 1243
1 Overview of functions | 1.1 Physical basics
Induced emission in the laser system
If a photon with the energy EB-EA impinges on an excited electron located at the
higher energy level EB, the drop to the basic energy level EA is greatly accelerated.
During this drop of the electron to level EA, an identical photon is released. The
triggering original photon remains in existence. This process is called induced emis‐
sion. Both photons have the same energy, direction, temporal and spatial phases.
This starts an avalanche effect which is amplified by the optical resonator since
these photons, reflected by the HR and AR mirrors, move through the laser medium
several times. The result is a radiating laser light source.
The figure shows the process of induced emission.
All of these processes are required for the laser to become active.
① Triggering photon
② Induced photon
③ Induced drop from excited electron
1
2
1
3
1
21
EB
EA
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