Research on microchannel fabrication in UV curable resin using combined beam processing

To break through the limitations of traditional rectangular microchannel processing methods for microfluidic devices, this paper proposes a processing technique based on a holographic combined femtosecond laser beam. The phase and topology of the hologram are adjusted by SLM to flexibly control the spot width and energy distribution of a generated Bessel beam, thus realizing high-precision and multi-size processing. To achieve high-precision microchannel sidewalls and bottom surfaces, the positive first-order Bessel beam is shifted at an appropriate position after the zero-order light by using a blazed grating to obtain the suggested holographic combined beam required for processing. At a laser power of 0.98 W, compared with using only the Gaussian beam (bottom roughness Ra of 0.361 μm, MRR of 882.219 μm³/s) and the Bessel beam (Ra of 0.377 μm, MRR of 3490.590 μm³/s), processing with the combined beam reduces Ra to 0.128 μm, a reduction by factors of 2.8 and 2.9, respectively. Meanwhile, the MRR increases to 6786.362 μm³/s, representing improvements by factors of 7.7 and 1.9, respectively. Under this power, when the phase value s increases by 4 pixels, the microchannel width increases by 3.2 μm, and when the topological charge n increases by 4 pixels, the microchannel depth decreases by 0.7 μm. This novel method, which enables smooth surfaces without the need for post-processing, offers a new option for the high-quality, efficient, and flexible fabrication of curable resin microfluidic devices.