Noncontact ballistic motion measurement using a fiber-optic confocal sensor

Abstract

A fiber-optic confocal sensor for noncontact ballistic measurements is described. Determination of motion at velocities of 1.7 km/s with an uncertainty as small as ±0.3% is demonstrated for both a projectile and a free-surface target. The fibers detect the passage of the object at their conjugate image points created by low F/# optics. This results in an output signal comprising a train of sharp pulses each precisely identifying when the ballistic object traverses an image point. Since the ballistic object does not contact the sensor at the time of imaging, the measurements do not perturb the motion, enabling multi-fragment measurement, as well as repetitive measurements of the same object point.

A Wireless Laser Displacement Sensor Node for Structural Health Monitoring

“…Therefore, an increasing demand exists for the use of these non-contact devices to measure the displacement of a structure for which the installation of devices is problematic. Certain examples of typical non-contact displacement transducers include eddy current sensors [ 24 ], capacitive sensors [ 25 ], confocal sensors [ 26 ], and optical sensors. The LLD-0100 model (JENOPTIK AG, Jena, Germany), with the ability to perform long-range measurements (0.2–35 m), is employed in this study.…”

Compact and rotationally invariant design of angle-polished optical fiber assembly emitting along the mechanical axis

“…Fiber-optic confocal sensors can be used for displacement [1,2] and velocity [3] measurement. These sensors use a coaxial optical system of a single fiber and a lens system to image light onto an object and measure the intensity of light scattered from the object through the same optics back into the fiber.…”