Measuring local moiré lattice heterogeneity of twisted bilayer graphene

We introduce a new method to continuously map inhomogeneities of moir\'e lattice and apply it large-area topographic images we measure on open-device twisted bilayer graphene (TBG). show that the variation in twist angle TBG device, which is frequently conjectured be reason for differences between devices with supposed similar angle, about 0.08{\deg} around average 2.02{\deg} over areas several hundred nm, comparable encapsulated hBN slabs. distinguish an effective local anisotropy relate latter heterostrain. Our results imply our devices, heterogeneity has roughly equal effect electronic structure as strain. The introduced here applicable from different imaging techniques, materials.