WARNING!!!! - When checking fiber attenuation, avoid direct eye exposure to laser light.
1. If the difference between P2 and P1 is greater than 1 dB, clean the optical fiber. If the difference between P2 and P1 is still greater than 1 dB, replace the optical fiber.
2. You are advised to select a wavelength near 1550 nm as the light source wavelength and set the wavelength of the optical power meter to 1550 nm. If the device has been powered on and has a board that can generate light, use this board as the light source
