Comparison between measured and fitted telescope beams at 300 GHz. Top: five measured beam maps with the receiver positioned at (50 mm, 50 mm), (50 mm,−50 mm), (0 mm, 0 mm), (−50 mm, 50 mm), and (−50 mm,−50 mm) relative to the focal-plane center (from left to right). These offsets correspond to (±50λ, ±50λ) at 300 GHz Bottom: corresponding best-fitting beam maps obtained from the multi-map holography analysis. The beam-map axes are shown in angular (u, υ) coordinates converted from the laboratory source scan positions measured with the XY translation stage. The color scale shows normalized beam power in dB, and each beam map is normalized to its own peak value.