Test Questions Flashcards
(194 cards)
1
Q
The same lens will focus different __________ to different ____________
A
wavelengths , focal lengths
2
Q
What are the laser operator functions?
A
ensure policies are followed such as: signs on doors and windows covered, glasses available and worn in NHZ, aiming beam checked for alignment with surgical beam in EVERY case.
3
Q
Wavelength: ArFi Excimer
A
193nm
4
Q
Because different wavelengths will have different focal lengths through the same lens, the ______________ and the _______________ maybe dramatically different sizes on the tissue.
A
surgical beam , aiming beam
5
Q
Degraded dye solution can show up in what ways when operating the laser?
A
Lower energies, misfires, and wavelength instability
6
Q
How many optics should you clean, remove, or adjust at one time?
A
one
7
Q
What are the ANSI documents relevant to our industry?
A
136.1 parent technical document and 136.3 safe use of lasers in health care facilities.
8
Q
Wavelength: Argon
A
488nm and 515nm
9
Q
Wavelength: nd:YAG
A
1064nm or 1.064u
10
Q
Wavelength: nd:YAP
A
1.34u
11
Q
Wavelength: Er:YAG
A
2.94u
12
Q
What is typical laser divergence?
A
0.5-10 milliradians
13
Q
How much amp draw does a typical Ion Laser power supply have?
A
30-50 amp draw
14
Q
Ho:YAG lasers typically display and measure energy in what unit?
A
joules
15
Q
What is an example of a use for CW dye lasers?
A
photodynamic treatment for cancer
16
Q
What wavelengths of light can transmit through glass?
A
300nm to 2800nm
17
Q
How often are diode lasers calibrated?
A
annually
18
Q
In focusing handpieces for incisions/ablations, the shorter the focal length the ___________ the spot and the __________ the depth of field.
A
shorter and smaller
19
Q
What is shock wave used for in pulse dye laser (green)?
A
urology - lithotripsy
20
Q
What is thermal, non lethal heat used for from laser?
A
Tissue welding, skin rejuvenation
21
Q
What does ANSI require when laser plume is created?
A
smoke evacuator
22
Q
Wavelength: KTP/KDP
A
532nm
23
Q
Wavelength: Copper bromide
A
577nm, 511nm
24
Q
Wavelength: pulsed dye, vascular
A
594nm
25
When brewster windows are now kept clean, what is the result in Ion lasers?
Power loss
26
How often should your external meter be sent in for calibration to a national standard?
annually
27
In multiline lasers _____________ is the sum of all wavelengths when they may be emitted simultaneously.
max power output
28
In aligning a q-switch ophthalmic yag laser, because of the location of the target, what must be avoided?
pitting of the lens that sits against the capsule
29
Describe articulated arm alignment process.
Place tape mark on aim beam, then rotate 180 degrees and observe.
Adjust beam 1/2 way to mark, and continue back and forth until corrected.
Never adjust directly to center
30
CW Dye lasers use what as a power supply?
Incoming beam from an Argon or KTP laser.
31
Radiant exposure or energy density is measured in _________
j/cm2
32
What kind of meter is used to measure wavelength stability in a CW dye laser?
monochrometer
33
What is the most common crystal for frequency doubling?
KTP (Potassium Titanyl Phosphate), but KDP or others possible
34
What interior component is the greatest hazard to service people?
Power supply
35
What is combine to create the dye solution in dye lasers?
dye concentrate, antifreeze (ethylene glycol) carrier along with C.O.T.
36
What can mimic a failing flash lamp?
Bad D.I. water
37
What is adjusted to find peak power?
OC and HR mirrors are walked as a pair to find peak power.
38
How does an AR coating work?
works by destructive interference pattern
39
Why are laser repair technicians at greater burn and exposure risk?
They are exposed to open housings
40
Class 4 lasers are anything...
over 0.5W average power or anything that burns the skin and eye.
41
What can sometimes stop flow in water pumps and how is it corrected?
Vapor locks, purge lines
42
Which direction does the coating face, how is that determined, and what are the consequences if it is in the wrong direction?
The coating faces the incoming beam. It is identified by the V or seeing the backside edge at a critical angle. Placing them in the wrong direction can reduce power or destroy proximal optics.
43
All other things equal, smaller focal length lens results in what?
Smaller spot and smaller depth of field
44
What guidelines are used for enforcement by OSHA, JCAHO, and various state agencies?
ANSI
45
What axis are used to align Ophthalmic Ar or Kr lasers into fiber?
x, y, z
46
Define the Maximum Permissible Exposure (MPE)
maximum exposure limit for eyes and skin before a burn will occur.
47
Explain how Nd:YAG, KTP, Argon, etc (other than CO2 and Er:YAG) lasers measure internal power and provide readout during use?
beam splitter creates a small optical "shunt" into the meter, so the meter reflects actual value during use.
48
What is "harder" on optics in terms of wavelengths and energy pusles?
higher energy pulse and shorter wavelengths
49
What does dichroic filter allow for?
selective transmission of wavelengths
50
Wavelength: XeCl Excimer
308nm
51
What are the power supply characteristics of flowing gas and DC excited sealed tube lasers?
high voltage and low current: 15-20kv and 15ma
52
How many shots pulsed is the typical life of a flashlamp?
150K to 250K
53
Wavelength: Ruby
694nm
54
What is the active medium in CO2 lasers?
CO2
55
What is a symptom of deionizer cartridge/crystals deteriorating?
power losses or intermittent firing
56
What is the process called that makes surgical instruments black to reduce reflections?
ebonization
57
What is the "far" beam alignment?
The beam combiner which passes surgical laser and reflects the HeNe aiming beam.
58
In a flowing gas CO2 laser vacuum system, what does higher vacuum create?
Thins out the molecules and lowers max power output, but increases stability at low power outputs.
59
What is the fastest way to change power density in the laser?
Spot size
60
How many hours is the typical life of a flash lamp in a CW laser?
150-200 hours
61
Are ANSI recommendations law?
No
62
What is the range of visible light in nm?
400nm - 700nm
63
At their maximum, can longer or shorter wavelengths be focused to a smaller spot size?
shorter wavelengths
64
Repeated start up attempts and a "cracking" noise can be a symptom of what?
gradually failing flash lamp
65
Should optics be removed to be cleaned?
not if it is safe to clean them in place.
66
why are collimated handpieces considered a hazard at a distance?
They will keep their spot size regardless of distance.
67
How are flash lamps cooled?
A flow tube is used to direct water tightly around the lamp for cooling.
68
At full operational power, what is the best indication of tube condition in an Ion Laser?
power or current, a combination of both is best.
69
In CW dye lasers, ______________________ are required to measure energy from many types of diffusers.
Spherical integrators
70
How do you work the near/far adjustment into alignment?
Alternate between near and far, bringing the HeNe back on top of burn spot each time
71
Laser output calibrations are recommended how often?
annually
72
Class 4 lasers require what precautions in what areas?
All precautions required in the NHZ
73
Increasing the beam diameter (and lens) at the same focal length will result in what?
Smaller spot
74
Why is depth of focus important when aligning beam into fiber?
You want to cover as much of the face of fiber as possible to avoid small point that bruns it.
75
What is the active medium in Ruby lasers?
chromium ions
76
What is the active medium in KTP laser?
neodymium
77
In a multiline laser, a single line emission will have more or less power output than the maximum multiline power?
less
78
List the components of an Ion laser tube.
-Ceramic or glass bore (tube).
-Surrounding magnet to "squeeze" the ionized plasma into the middle of the bore.
-anode and cathode
-"Getter" which pulls out impurities such as hydrogen which may be in the tube
-Brewster window at each end to seal the tube.
79
Describe the rear mirror in of the lasing medium?
Highly reflective mirror, isolated from the optical train. Can be adjusted independently.
80
What do ion lasers have to prevent overheating? What do they do when overheating occurs?
Ion lasers have overheat sensors (thermistors) that will shut the unit down.
81
When measuring average power at 10hz, how do you calculate the J/pulse?
divide by 10
82
Pulse energy in Joules x rate (PRR) =
an average power in watts
83
In flowing gas CO2 laser, what is intermittent firing, especially at low levels, potentially a sign of?
Vacuum leak
84
In a CO2 laser, what is the laser gas mixture?
Mostly helium (He), some nitrogen (N2), and least of all CO2. The N2 gives it the characteristic pink/purple color.
85
Who is the father of lasers in medicine?
Dr. Goldman
86
What is purge gas in a CO2 laser and what does it do?
Compressed air or bottled nitrogen, which is filtered and used to keep smoke off the lens.
87
What are the units of measurement for electromagnetic "radiation"?
angstrom, nanometer, or micrometer. 5320A = 532nm =.532u
88
Why should eye protection be worn when handling flash lamps?
pressurized and can explode
89
Higher Flux in laser pulses results in what for applications such as hair removal, skin resurfacing, vascular treatment, fine incisions, etc?
Less thermal spread from intended target
90
What problems develop if Dye lasers sit unused for too long?
coating of the dye and solvent on the optics and tubes
91
CW lasers generally display and measure energy in what unit?
watts
92
CO2 lasers typically display and measure energy in what unit?
watts
93
What is the cause of a beam that is easily controlled but causes charring, burning, and scarring in tissue?
Power density too low
94
List multiline laser types.
Argon, Krypton, CuBr
95
Wavelength: Alexandrite
755nm
96
Wavelength: Diodes
~530nm - 1500nm
97
Who determines the frequency of RF excited CO2 lasers?
manufacturer
98
How do some lasers reduce dust on brewster windows?
Protective covers with pressurized gas flow
99
In Ho:YAG lasers, what is used to protect laser optics from fiber fragments when exploded?
Blast shield
100
What is shock wave used for in Ho:YAG laser?
Urology, lithotripsy
101
What is the most common frequency doubled in lasers?
nd:YAG 1064nm to 532nm
102
Why does higher average power not necessarily mean a more powerful impact?
because average power is energy in joules x rate. A low energy at a high rate can have a higher average power than a high energy at a low rate.
103
What alignment is closest to HeNe and is reflective?
"near" beam adjustment
104
Argon lasers typically display and measure energy in what unit?
watts
105
Why do high energies have lower maximum rate?
They require longer recovery time
106
What can be said about power density if the cut is clean but uncontrollable?
Power density is too high
107
Wavelength: CO2
10.6u (micrometers)
108
What type of light is produced by a CW dye laser?
CW 630nm red light
109
What are indirect laser hazards?
Laser plume
Electrical (greatest hazard to repair tech, including direct beam)
Dyes and Solvents
Laser gases
110
Who invented the first Ruby laser?
Ted Maiman
111
Why can't sapphire contact tips or urological side firing fibers be fired into calibration port?
They will burn up
112
What does the Birefringent Tuner in a dye laser use to select wavelength?
dichroic filter in resonator cavity
113
What laser is the greatest burn hazard to laser technicians?
Co2 lasers
114
What is the partially reflective optic at the beginning of the optical train?
Output Coupler
115
1.5 Joules at 10hz will show as _____W average power. (or _____ J in one second)
15W or 15J
116
What is low level light therapy used for? (photobiomodulation)
chronic pain treatment, hair growth, wound healing, skin rejuvenation, etc. Also called cold therapy
117
When is radiant exposure / energy density used as a measurement?
When a "dosage" parameter of the laser is required, also used in IPLs
118
In aligning a q-switch ophthalmic yag laser, explain how the spark and red dot are aligned using the X, Y, and Z axis?
The red dot and spark are aligned on the X and Y axis. On the Z axis, the spark is placed just behind the red dot in the Z axis (depth) so that the dot focuses on the capsule and the spark occurs just behind it to create a shock wave that rips the membrane but spares the lens.
119
1W at .2s (.2J) is lower or higher flux than 2W at .1s (.2J)
lower flux (less energy more time)
120
In aligning a q-switch ophthalmic yag laser, the __________ is that target, which sits right against the new lens.
capsule
121
What are the typical power supplies of CO2 lasers?
Flowing gas and DC excited sealed tube or RF excited
122
How is AR coating calculated?
Coating is 1/4 of the wavelength of beam?
123
Ophthalmic diode lasers typically display and measure energy in what unit?
milliwatts
124
In flowing gas CO2 laser, what does excessive vacuum cause in anode and cathode?
Causes arcing and potential damage to laser electronics
125
What is the active medium in Ho:YAG?
holmium
126
List in order the hierarchy of laser eye hazards:
Pulse dye Yellow - high peak power and absorption by retina.
Infrared lasers - no aversion response
Visible light lasers - aversion response
CO2, Er:yag, and ArFl lasers - have lenses that focus short distance. Corneal hazard.
Ho:YAG - because of divergent fiber. Corneal hazard
127
Proximal changes affect all optics in which direction?
all "downstream" optics
128
What is the active medium in diode lasers?
the semiconductor
129
Lasers that operate at 632nm
Helium-Neon (HeNe), Gold Vapor, CW Dye (PDT)
130
What is the polarity of an anode vs cathode?
anode is negative and cathode is positive
131
How is RF transmitted in laser cavity?
transversely across cavity
132
Name the properties that make laser light different from "normal" light?
Collimated, coherent, monochromatic
133
What lasers don't transmit through glass?
CO2, Er:YAG, ArFl
134
Wavelength: Pulsed dye green, lithotripsy
604nm
135
How are transmitting fibers that diverge at 10-20 degrees used on tissue?
can touch tissue or be used off tissue
136
How should flash lamps be cleaned?
Clean like an optic, never rub rigorously
137
What is the primary reason for overheating in Ion lasers?
Forgetting to turn on the external water source
138
What is the formula for angular measure?
ratio of the arc length on the circumference of a circle by that angle, divided by its radius
139
What liquid is used in CO2 cooling systems?
distilled water, sometimes antifreeze solution if transported in cold environments.
140
Passbank currents or voltage regulation are characteristic of what kind of laser power supply?
Ion Lasers
141
How does anodizing surgical equipment reduce reflections?
It creates a micro-rough surface.
142
Most surgical diode lasers typically display and measure energy in what unit?
watts
143
What does the Maximum Permissible Exposure determine?
Boundaries for the NHZ
144
How much does lens of eye increase power density?
100,000
145
What are direct beam hazards?
eye burns or damage
skin burns
fires or burning of material
accidental surgical perforations
146
RF excited CO2 lasers measure their power in _______.
watts
147
Dichroic filters placed inside the resonator cavity will do what?
Allow lasing of only that wavelength.
148
What happens if Argon and Krypton lasers sit for too long unused
overgassing, use weekly
149
Define flux
concept of delivering more energy in shorter time periods to reduce thermal spread
150
How does beam diameter impact divergence? (all other things equal) on test for sure
The larger the diameter of the beam the lower the divergence.
151
List the ANSI recommendations for service training:
must have laser safety training
must have laser repair training commensurate with the level of work
no requirement for any educational background or certification
no requirements for authorization or approval from manufacturer
152
Wavelength: Krypton
647nm, 568nm, 531nm
153
What is the formula to calculate Joules?
watts x seconds = Joules
154
Is laser radiation a risk to pregnant women?
No, and this is on the test.
155
What are attenuators used for in lasers?
-aiming beam brightness
-some sealed tube CO2 lasers because they are unstable at very low currents
156
What is the spot size range in ophthalmic argon lasers?
~50u to .5mm
157
Pulsed dye lasers typically display and measure energy in what unit?
joules
158
In a flowing gas CO2 laser vacuum system, what does insufficient vacuum allow?
Allows more molecules in tube and higher power output, but becomes stable at low powers.
159
What laser has no optical assemblies except for delivery optics, and no optical adjustments? (it either works or does not)
Diode laser
160
In a 3 phase pump such as older nd:yag lasers, what does the polarity control?
direction of motor rotation
161
Ion Laser power supplies are powered by what kind of line voltage and at what voltage?
rectified AC line voltage ~240V
162
Frequency doubling in "quasi continuous" pulse systems operate at high frequencies over ________khz
20Khz
163
What is the required sequence of alignments in any laser?
Power tweaking, aiming beam coincidence, delivery system
164
Diode lasers are used as the pump source on some of these types of lasers?
Solid state
165
In free beam lasers (fibers or focused) what is generated when light is absorbed into tissue?
Heat is generated
166
If a CO2 laser completely stops working, and the tube lights up more purple/pink than normal, what is the likely problem?
A mix up of the purge gas and the laser gas. (tank swapping). Won't hurt the laser.
167
What are AR coatings used for?
Used to increase efficiency of optical coupling into optic and reduce losses
168
"Contact" fibers that have sharp or ball tips are used in what manner?
They get hot and cut tissue.
169
What is thermal, destructive heat used for with lasers?
cutting, ablating, photocoagulation, aesthetics, selective photothermolysis
170
You can use a power meter head to measure a pulsed laser by adjusting what?
repetition rate
171
What is the purpose of a Brewster Window?
enhances transmission (reduces reflection)
172
What can happen if water supply is turned on suddenly after overheating of an Ion laser?
cold water can crack the turb and cause extensive damage.
173
How do sapphire contact tips work?
Added to the end of the fiber catheter that converts the light energy into heat and work almost exclusively as a "hot knife".
174
What is the most important property of laser light in medical use? (on the test for sure)
Collimation because this is a "point source" of light with rays travelling parallel. Optics will focus this down to diffraction limited spot sizes (very small spots)
175
What is the biggest problem in CO2 cooling systems and what is done for it?
algae growth, change water and add inhibitors
176
What is indicated by an Ion laser tube having too low of voltage?
tube is underpressure. Fill from reservoir -ballast tank - with caution to not overfill.
177
In a 3 phase pump such as older nd:yag lasers, what happens if the polarity is reversed?
The pump spins the impellor in the wrong direction, possibly shearing it from the shaft and stopping water flow.
178
Pulsed lasers typically display and measure energy in what unit?
Joules or millijoules
179
In sterile procedures, what must be done for the calibration of a fiber?
sleeve sterilized and fiber handled with sterile gloves
180
At 1 milliradian, a spot would increase by ______ for every 1000 feet in distance travelled.
1 foot
181
What is the unit of measurement of beam divergence?
radian
182
What is "shock wave" used for in q-switched Nd:YAG lasers?
In Ophthalmology for posterior capsulotomy, and for tattoo removal
183
What is the active medium in Argon/Krypton lasers?
Argon and Krypton gasses
184
How large should the spot be on the laser meter/detector?
Fill about 75% of the face of the detector
185
Q-switched ophthalmic nd:YAG lasers (pulsed dye green for lithotripsy) typically display and measure energy in what unit?
millijoules
186
Explain how CO2 and Er:YAG lasers measure internal power and provide readout during use?
they use a shutter to totally dump the beam into calorimeter, during use the reading is only memory or current.
187
What wavelengths are retinal hazards?
between 400nm and 1400nm (includes all visible light lasers)
188
What is indicated by an Ion laser tube have too high of voltage?
tube is overpressure, burn off is needed.
189
What lasers are brewster windows typically used in?
Ion lasers: Argon and Krypton
190
List and describe the desired order of optic cleaning:
Drop and drag - sheet of lens paper
Twist and wipe - folded paper in hemos
Roll and wipe - cotton tip applicator
Rub and Scrub - cotton tip applicator
191
What angle are brewster windows?
57.3 degrees (for quartz) - where the surface does not reflect the light of one linear polarization.
192
Wavelength: Ho:YAG
2.1u
193
Because different wavelengths will have different focal lengths through the same lens, it can cause a loss of ______________ between the aiming and surgical laser.
coaxialness
194
How much variance is acceptable in laser output calibration?
+/-20%
