High-precision measuring circuit and length measuring instrument

The utility model relates to the technical field of cutter length and diameter measurement, in particular to a high-precision measuring circuit and a length measuring instrument provided with the high-precision measuring circuit, which comprise a driving module, a holding module, an input control module and a signal acquisition module, and are characterized in that the input control module is used for receiving control signals input from the outside; the holding module is used for emitting and receiving optical signals and transmitting different level signals to the driving module according to the received optical signals; the signal acquisition module is used for transmitting the optical signal received by the holding module to the input control module; and the driving module is used for amplifying the level signal and then outputting the level signal. According to the utility model, the structure is simple, and through cooperation of the driving module, the maintaining module, the input control module, the