| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for measuring the groove parameters of stamper for optical disc in which the groove width can be measured even for a stamper for optical disc having different track pitch. SOLUTION: When a stamper 1 for optical disc is irradiated with laser beam from the rear side, diffracted light is produced through a specific pattern of pit or groove formed on the surface of resist. Diffracted light of each order is detected by means of a line sensor 10 disposed at a distance L from the resist surface. Inter-spot distance D between zero and first order diffracted lights is then measured and a track pitch is calculated according to an equation; track pitch p=λ/sinθ, where diffraction angleθ=tan<-1> (D/L).λis the wavelength of laser light. Subsequently, a groove width (w) is determined from the calculated pitch and the ratio of quantity between second order and first order diffracted light. Furthermore, groove depth (d) is determined from the calculated pitch (p) and the ratio of quantity between first order and zero order diffracted light.
|
