Femtosecond lasers have an amazing array of possible applications, and this is especially true in the health and medicine industry. The low average power limits the amount of thermal damage to biological organisms, while the intensity and peak power are high enough to enable nonlinear processes for a range of medical uses from high-resolution microscopy to precise surgical procedures.
Some of the most common biomedical applications using femtosecond fiber lasers are described below.
Tissue Modification and Microsurgery
The unique properties of ultrashort pulse lasers that make them effective for micro-processing are also highly useful for performing complex or delicate surgical procedures. Femtosecond lasers allow precise removal of tissue with little or no damage to the surrounding areas.
One of the most established uses of femtosecond lasers for tissue modification is LASIK (Laser-Assisted In Situ Keratomileusis). The precision and minimal damage achievable with femtosecond pulses is ideal for cutting the delicate transparent cornea of the eye.
Even though the femtosecond LASIK procedure has been practiced for over a decade, improved laser processes are still being developed, such as all-femtosecond LASIK without the need of an excimer laser. In addition, new types of vision correction are gaining acceptance. A well-known example is cataract surgery, where the diseased lens can be broken up using a femtosecond laser. Another possibility is reducing presbyopia, the stiffening of the lens with age that prevents the eye from focusing on near objects. A network of fine laser cuts in the lens can restore flexibility, so the lens can change shape to focus on near objects.
Tissue Modification Papers
Medical Device Manufacturing
The unique ablation characteristics of femtosecond lasers render higher precision in micromachining while minimizing the size of the heat affected zone, as well as a reduction in debris, recast, and burrs. Additionally, they allow cutting, drilling, and welding of transparent materials with less collateral damage to the work piece. These unique processing capabilities are utilized in the semiconductor industry as well. The remarkably clean ablation stems from the extremely short deposition of the laser pulse energy, which ablates the material effectively before the absorbed laser energy dissipates as heat to the surrounding area of the ablation.
This process is very important for manufacturing medical devices such as vascular stents, where fine, clean cuts, produced without altering the properties of the surrounding material by heat transfer, are required to improve the performance of the device and its lifetime inside the body.
In many types of biomedical imaging, an excitation laser source causes a target molecule in a biological sample to fluoresce. Some types of naturally occurring biological cells will fluoresce when excited by the appropriate wavelength. In other cases, a fluorescent molecule can be introduced into the tissue which targets and attaches itself to specific cells. Using nonlinear absorption, only the region of the laser focus has sufficient intensity to excite fluorescence. This fluorescence can be used to map the tissue by scanning the laser focus across a 3-dimensional grid in the sample. The ultrashort pulse duration of femtosecond lasers allows for strong nonlinear excitation without photodamage caused by high average laser power. Efforts are being made to transition the R&D optical imaging system to a clinically deployable one. IMRA’s stable, robust and compact Femtosecond Fiber Lasers are helping with this transition, providing the best reliability in the industry.