1/82
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Speed (Light)
3×108 m/s or 186,000 mi/s
Wavelength
Distance between two successive light waves
Shorter wavelengths have ___ energy, while longer wavelengths have ___.
More, less
Frequency
How many waves pass a given point in one second
Amplitude
Height of a wave
Absorption
Caused by impurities or loss
Specular reflection
Angle of incidence is equal to the angle of reflection
Diffuse reflection
Angle of reflection is random
Scattering (diffused)
Caused by impurites
Refraction
Bending of a wave when it enters a medium where its speed is different
Transmittance
The fraction of radiant energy that passes through a substance
Flat mirror
A mirror where angle of incidence is equal to the angle of reflection
Concave mirror
Light is directed/concentrated to a single point or focal spot
Convex mirror
Dispersion of light in an outward direction
Fiber Optic cable has three main parts:
Core
Cladding
Buffering coating
How to repair fiber optic cables
Cut
Polish and reconnect
Test
Check for black dots
Five parts of an optical microscopes:
Lenses
Focus adjustments
Support and alignment
Specimen control
Illumination
Brightfield
Uses transmitted light to observe targets at high magnification
Phase-Contrast
Modified brightfield microscope that uses additional lenses and angles to vary the light density on the specimen
Darkfield
Microscope that uses a special condenser lens with an opaque disc so that direct rays of light don’t enter the objective lens
Binocular stereoscopic
Allows easy observation of 3D objects at low magnification
Differential interference contrast
Provides better image than phase-contrast. Measures dry weight, thickness and water content of the specimen
Ultraviolet
This microscope illuminates the specimen using ultraviolet rays from a mercury or iodine-quartz lamp
Fluorescence
Uses mercury or xenon lamps to produce ultraviolet light
Two uses of microscopes in medicine
Surgery
Tests/treatment
Laser
Light Amplification by the Stimulated Emission of Raditation
Lasers produce photons of electromagnetic energy that can be…
Within, above, or below the range of visible light
Laser light contains three qualities:
Monochromatic
Collimated
Coherent
Monochromatic
Single, very precise, frequency which gives a specific color
Collimated
Tight, narrow beam that needs to be maintained over a long distance
Coherent
Waves of light are in phase
Spontaneous Emission
Emission of light induced by an external energy source
Stimulated Emission
Emission of light after population inversion of the medium has been achieved by the spontaneously emitted photons
Light
Type of electromagnetic radiation
Visible light
~400 nm to 700 nm on the electromagnetic spectrum
Ocular Focus Region
Human eye can focus light onto retina from 400 nm all the way up to 1,400 nm
Infrared and ultraviolet light are..
Outside of the visible spectrum
White light contains…
All the colors of the electromagnetic spectrum
Amplification
Taking small electronic signal and increasing it enough to have useful output
SE
Stimulated Emission is a process that starts with spontaneous emission
Spontaneous Emission
electron in an excited state (higher energy level) naturally falls down to a lower energy level on its own, without any external influence. When it does this, it releases a photon (light).
Stimulate Emission
electron in an excited state falls to a lower energy level because it is stimulated by an incoming photon (light)
Optical Resonator
A container that has an inner mirror-like finish to keep photons inside with Totally Reflective (TR) rear mirror and a Partially Reflective (PR) front mirror.
Population inversion
A state at which most of the atoms in the container have been stimulated
What is needed create laser light?
Same wavelength
Same energy source that excited them
Same amplitude and wavelength
In phase
Totally Reflective (TR) rear mirror
100% reflective
Partially Reflective (PR) front mirror
Typically 80-95% reflective
Radiation
Refers to all of the electromagnetic spectrum
Types of Surgical Laser Systems
Gas
Solid State
Dye
Diode
Coherence
Light waves that are monochromatic and in phase
Photothermolysis
Heat damage by use of electromagnetic waves produced by lasers
Thermal relaxation time
Cooling rate of an object, meant to minimize damage to the surrounding tissue not targeted by the laser
Four types of surgical laser system run off:
Continuous wave (CW)
Long-pulse
Short-pulse
Q-switch
Delivery devices include:
Fiber optic cables
Articulate arms
Specialty glass components
CO2 lasers
Referred as “Surgical laser” that achieves both cutting and hemostasis photothermally, operating at 10,600 nm infrared light CW
Argon lasers
Blue-green light @ 488 nm and 514 nm
Significant non-selective heating
Excimer laser
disrupts the molecular bonds of surface tissue, causing ablation rather than burning or cutting
Argon: Fluorine laser @ 192 nm
Used in PRK and LASIK
YAG (Yttrium-aluminum-garnet)
Uses rare earth metals as lasing medium and operate in all types of modes
Nd:YAG lasers
1064 nm (sometimes 946 nm, 1120 nm, 1320 nm, & 1440 nm)
Used for black tattoo ink and hair removal
KTP lasers
Brilliant green light @ 532 nm
CW to cut tissue
Pulsed for vascular lesions
Q-switched for red/orange tattoo removal
Er:YAG lasers
2940 nm
Ablate tissue for cosmetic laser resurfacing
Benefits include: short downtime, less invasive, & minimal thermal injury
Also effective in tooth decay removal
Ho:YAG lasers
2070 nm
Ablate bone and cartilage
Lithotripsy
ENT
Prostate
Orthopedics
Ruby lasers
Red @ 694 nm
Extensively used in tattoo and hair removal
Alexandrite lasers
Chromium-doped solid-state laser
Hair removal for light/olive colored skin
Causes burns towards darker skin colored individuals
Pulsed Dye or Rhodamine Dye lasers
Yellow @ 577-585 nm
Peak absorption of hemoglobin in blood
Causing unsightly purpura (black and blue marks)
Diode lasers
"Injection Laser” or “Injection Laser Diode”
Often used in dentistry
500-900 °C
Laser systems are either:
Mounted to wheeled carts
Sit on top of a countertop
Laser safety classifications
Levels 1, 2, 3, & 4
Class 2 lasers
Limited to 1 mW
Less than 250 ms of exposure is not hazardous
Class 3R lasers
Limited to 5 mW in CW
Momentary unintentional exposure is not considered hazardous
Class 3B lasers
Can cause eye and tissue damage
Equipped with a key switch and a safety interlock
Class 4 lasers
Pulsed or CW
reflected or diffused reflected beams are hazardous
Greater than 0.5 W
Medical laser safety classification
Class 4 lasers
Nominal ocular hazard distance
Distance from source which intensity of energy per surface unit becomes lower than Maximum Permissible Exposure on cornea or skin
Nominal ocular hazard area
Depends on the area around the laser and refers to all space around the laser
Class 3B and 4 lasers have five main safety features:
Key switch
safety interlock dongle
power indicator
aperture shutter
emission delay
Safe use regulations adopted by CDRH
ANSI Z136.1 - American National Standards for the Safe Use of Lasers
ANSI Z136.3 - American National Standards for the Safe Use of Lasers in Health Care
Laser Safety Officer’s responsibilities:
Evaluation of Class 3B and 4 laser system
Recommend PPE or screens
Enforcing procedures to limit personnel exposure
Conduct operational checks
Comply with prescribed safety procedures
Maintain records required by government regulations
Posted warning signs must include:
Type of laser
Wavelength
Maximum output
Pulse duration (if applicable)
Cataracts (clouding of the eye lens)
Lens of eye can absorb the NEAR ultraviolet radiation (315-400 nm)
Cornea absorbs ___ and ___ waves which can cause severe pain, conjunctivitis and/or corneal damage
Far ultraviolet (180-315 nm), Far infrared (1,400-100,000 nm)
Safety glasses/goggles must have the correct…
Optical Density (OD) and wavelength
How to assure maximum flow rate of the smoke evacuator?
Within 5 cm of the treatment site
Change filters regularly