摘要 |
<p>An optical transducer according to the invention comprises optical detection means (1) including a first (1A), a second (1B), a third (1C) and a fourth optical detector (1D), such that a first imaginary line (2a) from the third optical detector (1C) to the first optical detector crosses a second imaginary line (2b) from the second optical detector (1B) to the fourth optical detector (1D). The optical detectors generate detection signals (A,B,C,D) in response to an intensity of radiation incident thereon. The optical transducer further comprises signal combination means (4) for generating a first, a second, a third and a second combination signal. The first and the second combination signals (AC+, AC-) are indicative for the sum of the electrical detection signals (A,C) of the first (1A) and the third optical detector (1C). The third (BD+) and the fourth combination signal (BD-) each are indicative for the sum of the electrical detection signals (B,D) of the second (1B) and the fourth optical detector (1D). The first (AC+) and the second combination signal (AC-) have a mutually opposite phase. The third (BD+) and the fourth combination signal (BD-) also have a mutually opposite phase.</p> |