Patent ID: 7495995

Claim:
An apparatus for investigating a formation, comprising: a caliper adapted to be suspended into a formation such that an axis of the caliper is substantially parallel with the longitudinal axis of the formation, wherein the caliper comprises: a transmitter for transmitting a transmitted pulse signal; a detector for detecting a reflected pulse signal, wherein the reflected pulse signal is the transmitted pulse signal reflected from a target location on a surface of the formation onto which the transmitted pulse signal is incident; a means for determining the time interval between the transmission of the transmitted pulse signal and the detection of the reflected pulse signal, wherein the distance from the transmitter to the target location on the surface of the formation and back to the detector is the time interval between the transmission of the transmitted pulse signal and the detection of the reflected pulse signal times the speed of the first pulse signal; a means for rotating the transmitter and the detector with respect to the axis of the caliper, wherein rotation of the transmitter and the detector causes the target location on the surface of the formation onto which the transmitted pulse signal is incident to rotate with respect to the axis of the caliper; a means for raising and lowering the caliper in the formation, wherein raising and lowering the caliper in the formation causes the target location on the surface of the formation to raise and lower, respectively; and one or more guide cables for guiding the caliper as the caliper is raised and/or lowered in the formation, wherein the one or more guide cables allow the position of the caliper to be controlled as the caliper is raised and/or lowered in the formation.