To use Shanglaite's biotherapy PDT device properly, several steps should be followed. First, ensure that the treatment area is clean and dry. Remove any makeup, creams, or lotions from the skin to allow for optimal penetration of the photosensitizer (if applicable) and light energy. Next, apply the photosensitizer according to the product instructions. Some PDT treatments may require the application of a topical photosensitizer, which should be evenly spread over the treatment area and left on for the recommended duration to allow it to be absorbed by the skin cells. Then, power on the PDT device and adjust the settings as per the treatment protocol. This includes selecting the appropriate light wavelength, intensity, and treatment time. Different skin conditions and treatment goals may require specific settings. For example, acne treatment may use a shorter treatment time and a specific wavelength compared to skin rejuvenation treatments. During the treatment, position the device at the correct distance from the skin, usually as specified in the user manual. Ensure that the light is evenly distributed over the treatment area. Avoid direct eye exposure to the light by using protective eyewear provided with the device. After the treatment, follow the post - treatment care instructions. This may include avoiding sun exposure for a certain period, using gentle skincare products, and keeping the treated area clean. Regularly monitor the skin's response to the treatment and consult a professional if any adverse reactions occur or if you have any questions about the treatment process.