Coaxial time-of-flight fiber distance measurement

In a laser tissue ablation system, a distal end of an optical fiber may extend from an endoscope. The optical fiber may receive a therapeutic laser pulse at a first time, receive a measurement light pulse at a second time, direct the therapeutic laser pulse and the measurement light pulse toward a target, collect at least some of the measurement light pulses reflected from the target as collected light pulses, and transmit the collected light pulses to the optical fiber. And directing at least some of the collected light pulses away from the distal end of the optical fiber as return light pulses. The optical detector may sense at least some of the return light pulses. The processor circuitry may perform a time-of-flight analysis on the sensed return light pulses to determine a spacing between the distal end of the fiber and the target, and may generate a spacing data signal representative of the determined spacing. 在激光组织消融系统中，光纤的远端可以从内窥镜中延伸。光纤可以在第一时间接收治疗激光脉冲，在第二时间接收测量光脉冲，引导治疗激光脉冲和测量光脉冲朝向目标，收集从目标反射的测量光脉冲中的至少一些