The invention of the optical frequency comb source, a light source that generates evenly spaced, discrete, narrow frequency lines, has revolutionized precision measurement and spectroscopy. By establishing an unprecedented link between optical and microwave frequencies, it has driven breakthroughs in timekeeping, fundamental physics, and optical communications. In astronomy, optical frequency combs serve as broadband, precisely calibrated spectral rulers, providing the accuracy required for next-generation high- resolution spectrographs. Their absolute traceability enables comparisons of astronomical observations over timescales ranging from days to years, even across different observatories. Despite their potential to significantly impact the field, the development of astrocombs faces considerable technical challenges. These stem from the competing requirements of achieving large comb-line spacings in the 5–50 GHz range while maintaining broad spectral coverage, from 380 nm (Ca II H and K lines) to 2.4 μm (CO band at 2.3 μm). In this seminar, I will first introduce the photonic technology behind optical frequency comb sources and their application in astronomical spectrograph calibration. I will then discuss the design of a novel ultra-broadband astrocomb spanning 400 nm to 2400 nm, with a fractional frequency accuracy of 10-12 maintained over years of operation. This fully transportable astrocomb will be installed at the Telescopio Nazionale Galileo, enabling simultaneous calibration of the HARPS-N (383–693 nm) and GIANO-B (900–2400 nm) spectrographs, achieving radial velocity precision down to 1 m/s.