Development sensor apparatus for monitoring the progression of development of an optical disk master

摘要

A development sensor apparatus includes an optical system, a 0th-order light detection unit, a 1st-order light detection unit, a diffracted light ratio calculating unit, and an ellipsoidal mirror. The optical system radiates a laser beam to a predetermined development monitor point on a pattern surface of a master having an exposed pattern. The 0th-order light detection unit receives a 0th-order diffracted light component from the development monitor point. The 1st-order light detection unit receives reflected light of a 1st-order diffracted light component from the development monitor point. The diffracted light ratio calculating unit calculates a ratio of diffracted light amounts of the 0th- and 1st- order diffracted light components based on detection signals of the 0th- and 1st-order light detection units and outputs a development monitor signal. The ellipsoidal mirror is provided on an optical path of the 1st- order diffracted light component from the development monitor point and reflects the 1st-order diffracted light component from the development monitor point toward the 1st-order light detection unit.