Table 1. Calibration constants determined in different configurations.

instrument	placement	absorbance system			interference system			fluorescence system
		α (°)	R	Δs/s (%)	α (°)	R	Δs/s (%)	α (°)	R	Δs/s (%)
Larry	up/outside	0.51	1.0005	-0.05	0.16	1.0015	-0.15
	up/outside	2.40	0.9988	0.12	2.04	0.9996	0.04
	up/outside	5.83	0.9980	0.20	5.50	0.9986	0.14
	up/inside	2.65	1.0025	-0.25	3.01	1.0008	-0.08
	down/outside	0.63	0.9999	0.01	0.70	0.9989	0.11
Shemp	up/outside	0.88	1.0239	-2.39	0.53	1.0082	-0.82
	center steel mask*		1.0286	-2.86		1.0083	-0.83
Moe	up/inside							2.30	0.9979	0.21

Experiments were carried out sequentially without invoking instrument radial calibration functions in between. The placement ‘up’ and ‘down’ refers to the use of the artifact as the window preceding the centerpiece or following the centerpiece in the light path; ‘outside’ and ‘inside’ refers to whether the lithographic layer faces the vacuum or the centerpiece. The corrections to the s-values (Δs/s = 1 − R) show the magnitude of error that would be expected without calibration.

* For comparison, the steel mask introduced in previous external calibration work was mounted in the middle of the cell [21].