A new maskless lithography method based on harmonic diffractive microlens arrays with continuous relief is proposed. The method takes the harmonic diffractive microlens arrays with continuous relief as maskless lithography objective array to integrate the defocus-detecting array into the writing array by taking both the writing resolution and diffraction efficiency into consideration

and design the array with deep relief to make the fabrication of arrays easy. To verify its validity

continuous-relief harmonic diffractive microlens arrays with F/7.5 and a design wavelength of 441.6nm are designed

fabricated and characterized for maskless lithography. Experimental results indicate that the array developed can be used to synchronously focus the writing laser and the autofocusing laser into the same spots

and can achieve diffraction efficiency of over 70% for both writing wavelength and defocus-detecting wavelength.