Why are laser protective lenses prone to black spots？

Why are laser protective lenses prone to black spots

In laser cutting machines and drilling, black spots appear on the laser protective lens after a period of use. The small black spots are mostly generated by slag splashing and sticking to the quartz lens during the drilling and cutting process. The focus lens in the cutting head of the optical brazing laser cutting machine is more expensive, and the protective lens is designed to protect the focus lens. Due to the continuous growth and erosion of black spots during the process of light emission, the protective lens is designed to protect the focus lens, Until the center position of the lens is reduced due to the focus drift caused by the thermal lens effect of overheating and expansion.

What are the reasons for black spots/burning spots, oil stains/dust, and moisture on the protective lenses during laser cutting?

What is the reason for the black spots/burnt spots on the lower protective lens of laser cutting?

Reason 1: The perforation focus is too negative, causing the perforation slag to return to the laser cutting machine lens.

Solution: Raise the perforation focus.

Reason 2: Inappropriate perforation energy, excessive perforation time, and perforation explosion.

Solution: Reduce the duty cycle and increase perforation time

Reason 3: Common edge layout cutting of parts, deformation of the plate and inability to connect the cutting tool. Solution: Add perforations at the common edge cutting position, or add micro connections to the layout parts.

Reason 4: Metal particle pollution in the gas pipeline Solution: Clean or replace the pipeline, find the source of metal dust generation, and replace it (at the pipe joint connection, etc.)

What is the reason for oil, dust, and moisture on the protective lenses during laser cutting?

Reason 1: The air compressor filtration does not meet the usage standards. Solution: Check if the filter element of the air compressor is ineffective or increase the filtration level.

Reason 2: The gas pipeline is not clean

Solution: Unplug the intake pipe of the cutting head, pour high-purity alcohol into the air inlet of the machine tool with atmospheric pressure for flushing, repeatedly clean the pipeline 3-4 times, or replace the air pipeline.

Reason three: The filter screen at the inlet of the fiber laser cutting machine is blocked by raw material or other foreign objects. Solution: Disassemble the air inlet seat and check if there are foreign objects blocking the filter screen of the air inlet seat.