The PDT device uses photochemical reactions of photosensitive substances to produce reactive oxygen species, which can damage tumor cells and cause tumor cells to degeneration and necrosis, while normal cells can absorb the laser, this is called photodynamic therapy. Normal cells metabolize faster than tumor tissues, so normal cells are almost unaffected and can be selectively treated for cancer with small side effects after operation.The PDT device limits the absorption wavelength of the photosensitive substance to 620-670nm. The YAG-OPO laser has the wavelength variability corresponding to the absorption wavelength of the new photosensitive material.
Theotry
The main components of device are:
Gain medium Er: Yb Glass
Used to produce a laser of 1.5 μm. The Er is a three-level structure with low absorption of pump radiation and relatively low output energy. However, because it emits a laser with a wavelength of 1.5 μm, it is the safest for the human eye and penetrates well in smoke. It has broad prospects in both military and civilian applications.
Q switch——A good saturable absorber should have a relatively long laser state lifetime and a large absorption cross section. Co2+ has a large absorption cross section and has different excited state lifetimes in different matrices. Co-doped materials such as Co2+:MgAl2O3 have exhibited good saturable absorption characteristics in the near infrared. A significant advantage of the Co2+ doped Q switch is that it can operate at high repetition rates.
Mirror——Allowing light to be reflected back and forth within the cavity.
Er3+/Yb3+ co-doped phosphate glass emits a laser that is safe and easy to measure in the 1540 nm band, and this band also corresponds to the low-loss window of the fiber. Lasers made with this material have broad application in optical communication, laser radar, Laser ranging and other aspects. Because the visual medium has a low transmittance to laser radiation of 1.53~1.56μm wavelength and it is not easy to damage the retina, lasers made of this material can also be used in the medical field, and there have been reports of successful treatment of corneal diseases.
Feature
- Can be strongly absorbed by water
- High reliability and low cost
- Simple structure
- In the communication window
- In the human eye safety band
Application
- Treating Acne Scars
The commonly used lattice lasers for the treatment of acne scars are non-exfoliated erbium-doped glass fiber lasers with a wavelength of 1 550 nm and ultra-pulsed carbon dioxide lattice lasers with a wavelength of 10 600 nm. They have achieved remarkable effects in the treatment of acne scars. The side reactions of CO2 laser single treatment were significantly higher than those of erbium-doped laser.
- The Treatment Of Melasma
Chloasma is a common clinically acquired pigment-enhancing disease, which often occurs in the exposed area and seriously affects the appearance and beauty of the patient. 1 540nm non-exfoliation lattice laser treatment of chloasma is effective, safe, and has no obvious side effects. It is a new treatment option.
- The Treatment Of Inflammatory Facial Acne
1 550nm Er glass dot matrix laser is a new type of mid-infrared laser, which has been widely used in the treatment of various skin diseases such as scars, wrinkles and chloasma. It is used for non-exfoliating skin remodeling and In the treatment of some pigmented skin diseases, the patient has mild pain and less adverse reactions.
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