How to solve the problem of Dark spots observed in IPL hair removal systems?

When the customer encountered this issue, we performed a series of systematic checks:

1. First, confirm the raw materials and coating process of the lens.
2. Checked the output energy level of the IPL device to ensure compatibility with the filter’s material and coating specifications.
3. Make sure there are no issues with heat dissipation.
4. Verify the correct orientation of the coated surface.

In the end, based on the customer’s decision, they simply changed the orientation of the filter installation while keeping the cost unchanged, and solved this problem.