Table 1.

Spatial dimensions of gratings

SET	SF (bars/m)	Period (mm)	Groove width (mm)
24	219	4.57	4.27
	238	4.20	3.90
	260	3.85	3.55
	283	3.53	3.23
	309	3.24	2.94
	337	2.97	2.67
	367	2.72	2.42
	400	2.50	2.20
48	438	2.28	1.98
	477	2.10	1.80
	520	1.92	1.62
	567	1.76	1.46
	618	1.62	1.32
	673	1.49	1.19
	734	1.36	1.06
	800	1.25	0.95

Each set (“24” and “48”) contained eight gratings with various spatial frequencies (SF), spatial periods (i.e., the distance between two adjacent ridge onsets), and groove widths (i.e., the distance between ridge offset to ridge onset).