Abstract: A fiber optic proximity detector for use in sensing the relative position of an object or change thereof wherein the light is reflected by the target surface and returned along the transmitting fibers and utilized along with the reflected light returned along the receiving fibers so as to effect automatic surface reflectivity compensation with the detector being coupled to an optical extender to increase the working distance of the probe from the target.

Abstract: A proximity sensor is disclosed having two bifurcate fiber optical bundles arranged in series. Light is directed at a target by the bundles and the reflected light from the target is transmitted to two different sensors. The output of the sensors is used to derive a differential control signal for tracking a target. One of the sensors picks up reflected light from the fibers which also transmit light to the target while the second sensor detects light from receiver fibers disposed around said transmitter fibers.

Abstract: A displacement measuring instrument for measuring the displacement of a target including in combination a fiber optic lens assembly including means for maintaining said assembly in space relation with said target, dither means for vibrating said assembly toward and away from said target about the lens null along the axis of said assembly, first electronic means for providing a first output voltage proportional to displacement of said assembly from said target, second electronic means cancelling that portion of said first output voltage resulting from displacement due to said dither means and providing a second voltage resulting from displacement due to means other than said dither means, servo means receiving said second output voltage and moving said assembly with respect to said target to null said second output voltage and measurement means measuring the movement of said servo means.

Abstract: A fiber optic proximity measuring instrument for measuring dynamic changes in the gap between a probe tip and a target includes a light source, two sensors for measuring reflected light and lamp brightness, and a light conducting cable for transmitting light to the target and conducting light reflected from the target back to the reflected light sensor. The lamp intensity is set by a brightness control during setup to produce a mean level of reflected light intensity, and then is automatically regulated to maintain an equal mean intensity at the reflected light sensor despite changes in target reflectivity and cable light conductance.

Abstract: A fiber optic proximity measuring instrument for measuring dynamic changes in the gap between a probe tip and a target includes a light source, two sensors for measuring reflected light and lamp brightness, and a light conducting cable for transmitting light to the target and conducting light reflected from the target back to the reflected light sensor. The lamp intensity is set by a brightness control during setup to produce a mean level of reflected light intensity, and then is automatically regulated to maintain an equal mean intensity at the reflected light sensor despite changes in target reflectivity and cable light conductance.

Abstract: A new capacitance type non-contact displacement and/or vibration measurement instrument sensing head is described together with a novel method of maintaining calibration of the instrument using such sensing head. The invention takes the form of a central probe member having a first guard ring disposed in coaxial, electrically insulated relationship about the central probe member and driven at the same potential and frequency as the probe member. A secondary driven guard ring coaxially surrounds the first guard ring and is electrically isolated from it and is driven at the same alternating current frequency but at a higher voltage of the order of 1.5 to 1 times higher. The additional secondary guard ring, driven at a suitably boosted voltage level and the same frequency as the central probe member, serves to focus the otherwise divergent electric field, thus producing a very significant improvement in the output linearity when operated at relatively large displacements.

Abstract: Fiber optic displacement/position measuring apparatus having increased working distance and measuring range capability is provided by combining an optical extending sensing head in fixed relationship with the common end of a bifurcated fiber optic bundle. The sensing head includes a lens system which is operative to focus the image of the end face of the fiber optic bundle onto the surface of an object whose displacement is to be determined and to refocus that image back onto the end in an upright relationship.