Processing of glass

The femtosecond laser micromachining technique has brought transparent materials processing to the next level. Complex structures can now be precisely fabricated by selectively removing material through drilling, cutting, and milling.

Glass Metal Polymer Other materials
Glass

Hybrid Laser Processing of Micro-Lens Arrays

Recent advancements in femtosecond laser technology have been heavily focused on addressing the industry’s longstanding challenge – low throughput. Burst mode processing has emerged as a breakthrough, not only attracting significant attention but also unlocking new application opportunities for femtosecond lasers. 

In burst mode, a single high-energy pulse is divided into multiple lower-energy pulses, allowing for more efficient use of laser power. This prevents excessive energy deposition, which would otherwise degrade processing quality. The high intra-burst repetition rate (ranging from MHz to GHz) ensures that each pulse actively contributes to material removal.

Illustration of burst mode operation

Illustration of burst mode operation.

Micro-lens array fabricated with hybrid laser processing method using the FemtoLux 30

Micro-lens array fabricated with hybrid laser processing method using the FemtoLux 30.

Courtesy of FTMC.

Conventional laser milling strategy struggles to achieve high aspect ratio geometries, as ablation debris accumulates within the ablation area, preventing further material removal and resulting in saturation of ablated depth. Alternatively, in the bottom-up milling technique, the laser beam is focused at the bottom of a sample. This method allows all ablation products to be removed through the backside of the sample, enabling the formation of high aspect ratio geometries in glass.

Illustration of TDM and BUM

Illustration of TDM and BUM.

As a demonstration of the FemtoLux 30’s capabilities, a micro-lens array was fabricated by employing hybrid laser processing: a combination of burst mode and bottom-up milling. The process involved multiple steps, beginning with the cutting of the device base from a thick fused-silica glass plate. Next, the lens array was ablated on the surface of the substrate, followed by CO₂ laser polishing to achieve optical quality. This application note highlights the versatility of the FemtoLux 30 and its applicability to manufacturing custom micro-optical elements.

For more details browse the Application Note Hybrid Laser Processing of Micro-Lens Arrays using FemtoLux 30.

Recommened products

FemtoLux

Industrial Femtosecond Lasers
  • 50 W / >300 µJ at 1030 nm
  • 20 W / >50 µJ at 515 nm
  • 10 W / >25 µJ at 343 nm
  • < 350 fs – 1 ps
  • Single shot to 4 MHz (AOM controlled)
  • MHz, GHz, MHz+GHz burst modes

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Micro-lens array fabricated with hybrid laser processing method using the FemtoLux 30
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Micro-lens array fabricated by employing hybrid laser processing: a combination of burst mode and bottom-up milling. 
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