25,000 optical fiber positioning robots for next-generation cosmology

Massively parallel multi-object spectrographs are on the leading edge of cosmology instrumentation. The highly successful Dark Energy Spectroscopic Instrument (DESI) which begun survey operations in May 2021, for example, has 5,000 robotically-actuated multimode fibers, which deliver light from thousands of individual galaxies and quasars simultaneously to an array of high-resolution spectrographs off-telescope. The redshifts are individually measured, thus providing 3D maps of the Universe in unprecedented detail, and enabling precise measurement of dark energy expansion and other key cosmological parameters. Here we present new work in the design and prototyping of the next generation of fiber-positioning robots. At 6.2 mm center-to-center pitch, with 1-2 um positioning precision, and in a scalable form factor, these devices will enable the next generation of cosmology instruments, scaling up to instruments with 10,000 to 25,000 fiber robots.