As the use of laser technology becomes a more integral tool in the field of aesthetic treatments, the ability to manipulate the output of the laser is increasingly important. Diffractive Optical Elements (DOE) provide a unique solution by allowing for the beam to be manipulated in a myriad of ways, and at the same time are thin and compact.
Skin resurfacing includes a wide range of treatments meant to rejuvenate the appearance of the skin from imperfections caused by many factors, including acne, scarring, and excessive sun exposure. Multispot elements have proven to be effective in assisting with more efficient skin resurfacing procedures. Creating a 2D matrix of smaller laser beams covers more area of the skin than a single laser beam, thus reducing procedure time. Moreover, healing time is shorter and more effective because the laser affects the skin in an even pattern, and the uneffected skin between spots allows for a shorter migration path for epidermal stem cells to develop and rejuvenate the skin.
Relevant products: Beam splitter
Common wavelengths: 10600 nm (CO2), 2940 nm (Er:YAG)
Figure 1. A gaussian input beam split into a 9x9 array.
Figure 2. Multispot set-up.
When using a non-uniform, or gaussian, beam when performing tattoo removal, this can cause "hot spots" on the skin of the patient since such a small area is so highly concentrated with laser power. This has several disadvantages, including increased healing time, increased procedure difficulty due to overlap of the laser pulses, and longer procedure duration. Using a top-hat beam shaper or homogenizer DOE creates a uniform beam that decreases the presence of hot spots, allowing for a shorter healing time; this is thanks to the less concentrated and more uniform energy distribution on the skin. Also, a homogenizer DOE makes it easier for the technician to perform the procedure in an effective way that provides uniform treatment on the entire effected area and minimal overlap between pulses. Moreover, the duration of the procedure is shortened because the DOE provides a larger effective area on the skin than an uneven beam profile.
Figure 3. A gaussian input beam converted into a round or square homogenized spot.
Figure 4. Homogenizer set-up.
Hair removal is another area of aesthetics where laser homogeneity provides a big advantage. Laser hair removal utilizes a technique called selective photothermolysis (SPTL), where targeted tissue is heated with minimal effect on adjacent tissue. The hair follicles in the target area are damaged, and the hair growth stunted. Using a non-uniform beam decreases the effectiveness of the SPTL; it becomes more difficult to know which part of the target area was affected and which was not. Also, due to the larger transfer region of a non-uniform beam, unintentional overlapping of the beam can occur, thus damaging the skin and causing uneven results. The use of a homogenizer DOE allows for a uniform beam profile which makes it easier to discern between affected regions and unaffected regions, and its narrow transfer region reduces the chance of unintentional overlapping. Additionally, the increased effected area of the beam on the skin causes a reduction in procedure time.
Laser body contouring is performed by shrinking subcutaneous fat cells with laser radiation. The use of a homogenizing DOE can assist in this treatment, and it can decrease unwanted side effects, such as skin blemishes and hyperpigmentation. By using a more uniform beam that covers a larger effected region on the body, procedure time is reduced, thus creating a more favorable experience for the patient and a more economical solution for the health care provider. Moreover, the even intensity distribution lowers the risk of burning and hyperpigmentation because the laser radiation is not so heavily concentrated in such a small area like with a regular gaussian beam.