| 摘要 |
PROBLEM TO BE SOLVED: To provide a measuring device achieving both measuring accuracy and measuring speed.SOLUTION: A measuring device comprises: a detector which detects modulation light from an object having a periodic pattern and outputs periodic pattern signals at least over two periods; and a calculation part which calculates an object position based on the outputs from the detector. The calculation part calculates the object position in the following steps: determining two positions of an extremal value appeared as a constant value over each period of the periodic patterns among the periodic pattern signals outputted from the detector; multiplying the periodic pattern signals in the region between the two extremal value positions by a first standard waveform data of a sign waveform having the same period as the periodic pattern signals have; calculating a first summation of the multiplied results; multiplying the periodic pattern signals in the region by a second standard waveform data of a sign waveform having a phase difference of 90 degrees from the first standard waveform data; calculating to obtain a second summation of the multiplied results; calculating a phase of the pattern signals based on the first summation and the second summation; and calculating the position of the object based on the calculated phase. |
