LASERS CERTIFICATION EXAM QUESTIONS AND CORRECT ANSWERS, WITH COMPLETE SOLUTION 2024.

LASERS CERTIFICATION EXAM QUESTIONS AND CORRECT ANSWERS, WITH COMPLETE SOLUTION 2024. Theorized the concept of stimulated emission Einstein Theorized that an excited electron will spontaneously return to its ground state Bohr First ruby laser was created in _____ by ______. 1960, Ted Maiman _________ reported in 1965 that a ruby laser could vaporize enamel. Stern and Sognnaes First pulsed Nd:YAG laser released in ______ and cuts ______ tissue. 1990, soft tissue In _____ the first dental hard tissue was FDA cleared and is called _______. And the ______ laser a year later. 1997 Er: YAG laser Er, Cr: YSGG The word LASER is an acronym standing for _________. Light Amplification by Stimulated Emission of Radiation Laser parameters include what 3 things? 1)Duration of exposure 2)Fiber Diameter 3)Wavelength Lasers are: ______chromatic? _____directional? coherent or noncoherent? emitted from a stimulated ____________. monochromatic: made of a single wavelength (visible or infrared) unidirectional coherent (all peaks and valleys of each wave travel in unison) active medium What states can the active medium be in? solid, gas, semiconductor What type of active medium is used in Er: YAG? solid state using crystal matrix (erbium laced yttrium, aluminum and garnet) What type of gas is used when the active medium is sealed in an air tight chamber? CO2 Diode lasers have what type of active medium? semiconductor what photons form the laser? light that leaks from the output coupler Stimulated emission: atoms of the active medium are stimulated to a higher energy level-- released as a photon as the atom returns to a more stable lower energy level. Amplification Released photons can go on to stimulate more atoms in the crystal, thus producing more photons Energy density depends on what 3 things? energy, divergence (tendency of a laser beam to spread outward=laser beam diameter increases), and distance Energy is measured in ______ Joules (millijoules) Power is ______ and is measured in _______ rate of doing work, or energy used over a period of time and is measured in Watts (J/sec) Frequency is measured in _____. Hertz ( laser pulses/sec) What is the most important variable dictating how the laser beam will interact with the target tissue? Peak Power Define Peak Power: power level in each individual laser pulse, however it is not visible to the operator Describe Peak Power in the 3 types: 1) Continuous 2) Gated 3) Free running pulsed 1) the peak power equals the average power displayed 2) Average power is half of peak power 3) Low Average power, very high peak power What are the two basic forms of pulsed laser modes? Gated wave Free running pulsed How is the gated wave pulse created? created with a shutter that blocks the laser beam from reaching the handpiece and target tissue at varying speeds: the laser is on constantly but the shutter device blocks the light from transmitting. (example: flashlight moving hand in front of it) How is the Free running pulse created? Not on constantly, but emit photons in powerful bursts of energy measured in millionths of seconds. (example: turning flashlight on and off) Which lasers operate in continuous mode? (can be mechanically turned into a gated mode when a shutter is used) CO2, Diode Which lasers operate in free running pulsed mode? Nd:YAG, Erbium lasers Shorter pulses ______ peak power (increase or decrease?) Which laser uses shorter pulses? increases Hard tissue lasers Define Thermal relaxation ability of the target tissue to absorb heat produced by laser interaction When does thermal relaxation occur? soft or hard tissue? ONLY occurs during soft tissue procedures Describe thermal relaxation in the three types of lasers. -Continuous mode: No thermal relaxation (damaging heat can build in the tissue quickly) -Gated wave mode: half on/half off exposure and the ability of the tissue to absorb the heat is limited -Free running pulsed: Thermal relaxation occurs the most (each pulse is very short so there is adequate time between each pulse to allow the tissue to absorb and dissipate the heat to minimize thermal damage: allows for lowered post op discomfort and predictable healing so some procedures can be done without anesthetic) ** analogy is if a finger is moved rapidly through a candle flame it will not burn as the tissue can absorb and dissipate the momentary high heat Placing the finger in the flame and holding it there will cause rapid thermal damage.** Describe the 4 types of interactions the laser has with the target 1) Absorption: chromophores absorb the photons, the light energy is then converted into thermal or mechanical energy to perform work (Preferred) 2) Reflection: The laser beam bounces off the surface with no penetration or interaction. (usually NOT preferred) 3) Transmission: laser can pass through superficial tissues to interact with deeper areas. (Nd:YAG and diode lasers) 4) Scattering: laser energy enters the target tissue will scatter in various directions. Define Chromophore: Light-Absorbing compounds or molecules normally occurring in tissues that are attractors of specific wavelengths What are absorbed by Nd: YAGs and Diodes? pigments: hemoglobin and melanin What part of the eye can diodes and Nd:YAGs cause damage to? Retina (because it has pigment) What are absorbed by Erbium and CO2? Water and erbium also does hydroxyappetite Which lasers penetrate tissue deeply? Nd: YAG ( shorter near infrared wavelengths) penetrate tissue deeper than the longer mid infrared wavelengths like Erbium and CO2 Which lasers are soft tissue cutting? Nd:YAG, Diode lasers,CO2, and Erbium (all 4) Which lasers are hard tissue cutting?