  Ballistic electrons in solids can have mean free paths far larger than the
smallest features patterned by lithography. This has allowed development and
study of solid-state electron-optical devices such as beam splitters and
quantum point contacts, which have informed our understanding of electron flow
and interactions. Recently, high-mobility graphene has emerged as an ideal
two-dimensional semimetal that hosts unique chiral electron-optical effects due
to its honeycomb crystalline lattice. However, this chiral transport prevents
simple use of electrostatic gates to define electron-optical devices in
graphene. Here, we present a method of creating highly-collimated electron
beams in graphene based on collinear pairs of slits, with absorptive sidewalls
between the slits. By this method, we achieve beams with angular width 18
degrees or narrower, and transmission matching semiclassical predictions.
