Device and method for measuring size of borehole wall hole by using scale light ruler

The invention belongs to the technical field of petroleum logging, and particularly relates to a device and a method for measuring the size of a borehole wall hole by using a scale light ruler. According to the technical scheme, the device for measuring the size of the borehole wall hole by using the scale light ruler comprises an underground tool unit, wherein the other end of the underground tool unit is rotationally connected with an underground television short section, a lens is installed on the underground television short section, a scale light ruler short section is further arranged at the end, away from the underground tool unit, of the underground television short section, and the scale light ruler short section is fixed to a rotating shaft of the underground television short section; and the meter light ruler short section is provided with a mesh hole which is used for projecting a shadow representing the size on the borehole wall to serve as the light ruler. The invention provides the device and t