Glossary

Use this alphabetical glossary for some of the important terminology associated with cosmetic laser treatments to familiarize yourself with some of the words you may encounter as you browse this website or begin your aesthetic treatment experience. For the Candela Corporation's glossary of laser terms, click here.

A
 

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

Aiming beam

     A second low power coaxial laser which provides a defined visible target area. Used with infrared or other invisible wavelengths

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

Articulated arm

     A laser delivery system that utilizes a jointed arm and mirrors

Atrophic

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

 

B
 

Becker's nevus

     Similar to but less common than Café-au-lait macules, and typically larger (5-40cm). Also have course hair present within the patch, and usually located in the shoulder area    

 

C
 

Café au lait

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

Cavitation

     Formation of a cavity or erosion

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

Collimated

     All the waves of the laser beam are parallel to each other and don't converge or diverge

Congenital nevi

     Nevi which 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 which 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    

 

D
 

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, ie. Articulating arm, fiber, hand piece

Dermatitis

     Inflammation of the skin

Dermis

     The deeper, thicker layer of skin beneath the epidermis which 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

 

E

Ectatic

     Dilatation of a hollow organ or tubular structure such as an enlarged blood vessel

Edema

      Swelling due to collection of fluid in interstitial space

EMLA

     Topical anesthetic cream --> containing 2.5%lidocaine and 2.5% prilocaine

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

 

F

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 degeneration being fair skin, easily burned - to type 6 never burn very dark skin

Flashlamp-excited

      Utilizing high intensity flashlamps to excite a lasing medium to produce laser energy

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 which provides the proper beam size

Focusing lens

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

 

G

Gating or shuttered pulse

     Method of using a mechanical shutter to produce a "pulsed" effect in a laser beam

 

H

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

 

I

Incoherent light

     White light, many wavelengths present, i.e. does not have the properties of a laser

Inflammation/inflammatory response

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

Intraoperative

     Meaning "during" the surgical procedure

 

J

Joule (J /(cm2)

     A measurement of energy density within a given spot size

 

K

Keloid

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

 

L

LASER

     Light Amplification by Stimulated Emission of Radiation

Laser parameters

     Characteristics of a laser beam, or the settings used on the laser device

Lentigines

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

 

M

Medium

     Substance which produces laser energy

Melanin

     Pigment which 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 .5 cm 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

Monte Carlo Simulation

      Computer optical simulation of photons moving through tissue based on optical properties

 

N

Nanometer

      10-9 meters, or .000000001 meters

Nanoseconds

      10-9 seconds, or .000000001 seconds

Nevus of Ota

      Blue gray lesion on the face most commonly seen in Asian populations. Dermal in depth, and usually seen around the eye, temple and cheek area.

Non-ionizing/ionizing radiation

      Non-ionizing forms of radiation include

 

O

Optical density

      Resistance of a substance to light energy

OSHA

      Occupational Safety and Health Administration    

 

P

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-acoustic

     Light that generates an acoustic shock wave effect in tissue

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 flames.

Post-inflammatory pigmentation

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

Postoperative

     Pertaining to after a surgical procedure

Preoperative

     Pertaining to prior to a surgical procedure

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.

 

Q

Q-switching
 
     The use of a pockel cell to generate very high peak power for a very short period of time, usually in the nanosecond range

 

R

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

 

S

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.

Stimulated emission

     Process by which a molecule emits two photons of light after absorbing one

 

T

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

 

U

Ulceration

     A depressed or eroded area in the skin

 

V

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.

 

W

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