Fused-silica focusing lens for deep UV laser processing

Area of Science:

• Optics and Photonics
• Materials Science
• Laser Technology

Background:

• Deep ultraviolet (UV) laser processing requires specialized optical components for precise focusing.
• Existing optical tools may not be optimized for the specific demands of deep UV wavelengths and high-power laser applications.

Purpose of the Study:

• To present a simple, four-element fused-silica lens designed for deep UV laser processing.
• To demonstrate the lens's capability in achieving high-precision micro-drilling of thin metal foils.

Main Methods:

• A four-element fused-silica lens with a focal length of 31.2 mm and f/1 relative aperture was designed using a practical method.
• The lens was utilized with an 8.5-mm beam diameter Nd:YAG laser at a 266 nm wavelength.
• Percussion drilling experiments were conducted on 25-microm-thick tantalum foil.

Main Results:

• The lens successfully enabled percussion drilling of tantalum foil, creating holes with a diameter of less than 6 micrometers.
• The shape of the drilled holes was consistent with Gaussian beam spot simulations, especially when the lens or sample was tilted.

Conclusions:

• The developed fused-silica lens is effective for high-precision focusing in deep UV laser processing.
• The lens design and performance are suitable for micro-machining applications, such as drilling thin metal foils with sub-micrometer accuracy.