Optical fiber bundle displacement sensor using an ac-modulated light source with subnanometer resolution and low thermal drift

Abstract

An optical fiber bundle displacement sensor with subnanometer order resolution and low thermal drift is proposed. The setup is based on a carrier amplifier system and involves techniques to eliminate fluctuation in the light power of the source. The achieved noise level of the sensor was 0.03nm/√Hz. The stability was estimated by comparing the outputs of two different sensors from the same target for 4 ks (67 min). The relative displacements between the fiber bundle ends of the two sensors and the target surface varied in the area of 400 nm depending on the ambient temperature variation at 2 °C. However, the difference in output between the two sensor systems is within 2 nm for more than 1 hour of measurement. It is expected that it would be reduced to within the area of 0.1 nm if the ambient temperature were controlled to within ±0.1 °C. It is concluded that the stability of the sensors is sufficiently good to be used with nanotechnological instruments.

<title>Smart fiber optical displacement submicrometers and their applications in a means of transport</title>

“…Therefore, we suggest that attenuators 4, 5 (Fig. ic of this article), which allow to regulate the amplitude of the output signals A anb B without changing the light stream intensity falling onto the mirror, should be introduced in the canals ofthe fibres A and B, since the resolution ability ofthe transducer depends upon the light stream'. Attenuators 4,5 ofthe light stream intensity (Fig. ic) are also necessary to prevent the sum of the signals A and B (A+B) from reaching values which are limited by the feed-in voltage of the amplifiers.…”

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An overview of magnetostriction, its use and methods to measure these properties

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