Glossary

Absorption
The act of tissue taking up laser energy, causing a reaction within the tissue

Absorption peak
Place on an absorption curve where light absorption by a chromophore in tissue is significant

Acne
A disorder of the skin caused by inflammation of sebaceous glands and hair follicles

Anatomical parts of hair
Follicle, bulb, bulge, vascular, supply (matrix) and hair shaft

Angioma (Cherry, spider)
Capillary hemangiomas. Flat or raised tumor composed of a mass of tiny blood vessels, bright red in color, usually 2-5mm in size

ANSI
American National Standards Institute – voluntary nationally recognized group establishing standards for equipment use. The ANSI Z136.3 standard pertains to the use of medical lasers

Atrophic
A wasting, progressive degeneration and loss of function of any part of the body

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Café-au-Lait
Light tan to light brown macules often apparent at birth, epidermal in depth, ranging from 1cm -20cm in diameter

Chloasma/Melasma
Light to medium brown discoloration of the face commonly associated with pregnancy; called “mask of pregnancy”

Chromophore
A target that absorbs light.

Class of lasers
Broad classification of lasers based on the ability to cause injury, Class I-IV, Class IV devices are the most dangerous / powerful

Coherent
All the waves of the laser beam are lined up in phase with each other in time and space

Collagen
An insoluble fibrous protein that is the chief constituent of the fibrils of connective tissue (as in skin and tendons) and of the organic substance of bones

Congenital nevi
Nevi that are present at birth

Congenital vascular malformation
General term for vascular lesion present at birth, such as Port Wine Stains, hemangiomas, and venous malformations

Corneal Shield
Protective covering that is inserted under the eyelid and placed directly onto the surface of the eye.

Cryogen
A substance used to induce a low temperature in an object

DCD
Dynamic Cooling Device which sprays a cryogen cooling agent on the skin prior to the laser pulse being fired or during a laser procedure

Delivery system
Components used to apply laser energy to a patient, i.e. Articulating arm, fiber, handpiece

Dermatitis
Inflammation of the skin

Dermis
The deeper, thicker layer of skin beneath the epidermis that contains blood vessels, nerves and hair

Distance gauge
A spacer between the handpiece lens and the treatment site, which if placed in contact with the skin, ensures that the beam is the proper focal distance

Edema
Swelling due to collection of fluid in interstitial space

Energy density
The amount of energy contained within a given spot size – see Joules

Epidermis
The outermost thin layer of skin

Epilation
The removal of hair

Erythema
Redness of the skin

Facial Telangiectasia
Dilation of a group of capillaries on the face, also called spider veins

Fiber
A quartz or glass filament used as a delivery system for laser energy

Fitzpatrick skin types
Classification system of skin types based on tanning characteristics and melanin content (Types 1-6). Type 1 being fair skin, easily burned – to type 6 never burn very dark skin

Fluence
The amount of energy delivered to the tissue calculated by Watts x Time divided by the spot size in cm2

Focal length
Distance between the lens and the focal point, or the distance from the lens that provides the proper beam size

Focusing lens
Lens used to focus the laser beam to a specific spot size

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Hair anatomy
Folicle, bulb, bulge, vascular supply, matrix, shaft

Hair growth cycle
The growth phases of hair

Hemangioma
Benign tumor made up of blood vessels

Hirsuitism
Excessive hair growth on cheek, chin, lip or chest; especially in women due to an increase in androgenic production

Hyperpigmentation
Increased pigmentation in tissue or skin

Hypertrophic
Enlargement of an organ or part due to the increased size of the cells composing it.

Hypopigmentation
Decreased pigmentation in tissue or skin

Inflammation/inflammatory response
Tissue reaction to irritation, infection, or injury marked by localized warmth, swelling, redness, and pain

Joule (J /(cm2)
A measurement of energy density within a given spot size

Keloid
A nodular mass of scar tissue that has grown well outside the original boundaries of a scar

Laser
Light Amplification by Stimulated Emission of Radiation

Laser parameters
Characteristics of a laser beam, or the settings used on the laser device, which may include

Lentigines
Small tan to brown epidermal lesions or macules usually arising from sun exposure which increase in number as a person ages.

Medium
Substance that produces laser energy

Melanin
Pigment that is produced by melanocytes in the skin

Melanocytes
Pigment producing cells in the skin

Melanocytic nevi
Medium to dark brown macules which are dermal in depth and tend to occur on the trunk and extremities. Can be from .5cm to several centimeters in diameter, and have a relative higher risk of becoming malignant.

Melanosomes
Melanin containing organs within the melanocytes

Microseconds
10-6 seconds, or .000001 seconds

Milliseconds
10-4 seconds or 1/1000th of a second

Monochromatic
Meaning one color; one specific wavelength of light.

Nanometer
10-9 meters, or .000000001 meters

Nanoseconds
10-9 seconds, or .000000001 seconds

Non-ionizing/ionizing radiation
Non-ionizing forms of radiation include

Optical density
Resistance of a substance to light energy

OSHA
Occupational Safety and Health Administration

Perifollicular edema
Swelling due to collection of fluid in the interstitial space in the area around the depression in the skin from which the hair emerges. Positive sign of proper energy delivered for hair removal

Photo-ablation
The act of removing tissue by vaporization with light

Photo-chemical
Act of light causing or initiating a chemical reaction

Photo-thermal
Action of turning light energy into heat.

Photons/ molecules of light
Light energy given off by an excited atom

Photosensitivity
Increased sensitivity to light

Pigmented Lesions
Congenital or acquired brown to black skin lesions

Poikiloderma of Civatte
Hyperpigmentation and telangiectasias of the sides of the neck and chest associated with chronic sun exposure

Port Wine Stain (PWS)
A pink to purple macular congenital vascular malformation of dermal vessels. Also called nevus flammeus.

Post-inflammatory pigmentation
Area(s) of darkening or increased pigment in a laser treated area after treatment.

Protons, neutrons, electrons
Basic components or building blocks of atoms

Pruritis
Itching

Pseudofolliculitus Barbae (PFB)
Beard bumps or razor bumps

Psoriasis
A common chronic skin disease characterized by varying sized reddish patches with white/silver scaly appearance. Occurs mostly on the elbows, knees, scalp, and trunk.

Pulse duration/length
The length of time a laser pulse lasts, usually in nanoseconds, microseconds, or milliseconds.

Pulse repetition rate
The rate at which a laser fires pulses, usually in pulses per second or Hertz (Hz)

Pulsed dye
Laser that produces light from an organic dye in solution

Pulsed vs. CW lasers
Lasers that generate short bursts or pulses of light vs. lasers that emit a continuous beam of light

Purpura
A purplish or blue/black discoloration of the skin after laser treatment, a bruise.

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Reflection
The act of light bouncing off of a surface after striking it

Resonator
Laser head or laser cavity, or laser tube. The place where the lasing medium is housed and the laser energy is produced

Rhytides
Wrinkles, lines or creases that appear most notably on the face as a person ages. Can increase with sun damage and smoking

Rosacea
Dilation of capillaries in the cheeks, nose, forehead and chin; adult onset acne and blushing or flushing induced by a variety of triggers

Scars
Fibrous tissue formed during the healing of a wound

Scattering
Process in which a light beam is split apart in many different directions after striking a object or tissue

Sclerotherapy
The injection of a chemical into a vein to obliterate the vessel

Sebaceous Hyperplasia
Enlargement of sebaceous glands.

Seborrheic Keratosis
A benign pigmented lesion which is raised, tan, brown or black colored, usually on the face, back and chest of older adults; may have a greasy wart-like appearance

Selective Photothermolysis
Theory on which lasers are designed which states that one chooses a laser wavelength that a target absorbs strongly, while surrounding structures do not, and having an exposure time less than the thermal relaxation time of the target

Selectivity
Absorption by a particular target, without effecting surrounding structures

Skin Rejuvenation
Erasing fine lines and wrinkles through the use of laser or light-based treatments

Spider Hemangioma
Arterial spider. A dilated arteriole of the skin with radiating capillary branches.

Spot size
Usually denotes the size of the treatment beam, can be expressed in circular diameter, or in the case of scanner handpieces, other geometric shapes.

Target
Tissue or substance a laser beam is directed at

Telangiectasia
Dilation of a group of capillaries, also called spider veins

Thermal injury
Damage to tissue from a heat source or photo-thermal reaction

Topical anesthesia
Anesthetic applied to the surface of the skin, usually a cream, liquid, or gel.

Transient / Transitory
Temporary

Transmission
The passage of energy through a medium

TRT
Thermal Relaxation Time – the time a target takes to release ½ the heat it had gained after being heated

Ulceration
A depressed or eroded area in the skin

Vascular Lesions
Vascular tissue exhibiting altoreal pathology.

Venous Lake
A superficial vein-like malformation usually located on the lips or ears. It is soft, compressible, flat or slightly elevated, bluish/red.

Warts
A small horny outgrowth on the skin, usually of viral origin, also called verucca

Wavelength
The distance between two consecutive peaks on a wave of light. Usually measured on micrometers or nanometers. Also determines the color of the light.

Wheal
Round or ridge-like transitory swelling on skin.

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