Table 2.

Overview of offline coating thickness methodologies.

Methodology	B1	B2	B3	B4
Thickness ranges	0.5–20 nm	0.1 nm–2 µm	0.1–100 nm	1 nm–50 µm
Measurement accuracy (%)	0.05	0.2	2–5	<5
Multi-layer	✓	✓	✓	✓
Sampling rate	1 m–4 h	1–5 m	5 m–1 h	3 s–12 m
Detection area (ø)	10 µm–5 mm	50 nm–1 cm	10–100 µm	Unspecified
Commercial availability	[63]	[64]	[65]	[66]
Typical cost (GBP)	>200,000	>50,000	>20,000	Unspecified
Non-contact	✓	✓	X	X
Non-destructive	✓	✓	✓	X
Materials	✓	✓	✓	✓