Table 2.

Optical properties of tissue layers at 750-nm wavelength.³²

Tissue layer	${\mu }_a$ (${\mathrm{mm}}^{-1}$)	${\mu }_{\mathrm{s}}^{\prime }$ (${\mathrm{mm}}^{-1}$)	Refractive index
Scalp	0.0170	0.74	1.33
Skull	0.0116	0.94	1.33
Cerebrospinal fluid	0.004	0.3	1.33
Gray matter	0.0180	0.84	1.33
White matter	0.0167	1.19	1.33