  Van der Waals layered materials with well-defined twist angles between the
crystal lattices of individual layers have attracted increasing attention due
to the emergence of unexpected material properties. As many properties
critically depend on the exact twist angle and its spatial homogeneity, there
is a need for a fast and non-invasive characterization technique of the local
twist angle, to be applied preferably right after stacking. We demonstrate that
confocal Raman spectroscopy can be utilized to spatially map the twist angle in
stacked bilayer graphene with an angle resolution of 0.01{\deg} for angles
between 6.5{\deg} and 8{\deg} when using a green excitation laser. The twist
angles can directly be extracted from the moir\'e superlattice-activated Raman
scattering process of the transverse acoustic (TA) phonon mode. Furthermore, we
show that the width of the TA Raman peak contains valuable information on
spatial twist-angle variations on length scales below the laser spot size of ~
500 nm.
