The invention discloses an air floating type rotary scanning measuring head device, which comprises an air floating main shaft, a measuring rod, a
torque motor, a circular
grating, a reading head, a photoelectric
slip ring and a
zoom lens, a rotor of the photoelectric
slip ring is connected with the
zoom lens, the
zoom lens is connected with the circular
grating, the
torque motor is connected between the circular
grating and the air floating main shaft, the
torque motor is connected with a core shaft of the air floating main shaft through a rotor rotating shaft, and the measuring rod is connected with the core shaft and is supported by the core shaft; the torque motor is used for driving the measuring rod to rotate, the circular grating is fixedly connected with a rotor of the torque motor, and the reading head reads a rotation angle; the photoelectric
slip ring is used for accessing a measuring
light beam, emergent light of the photoelectric slip ring enters the
zoom lens, and the
zoom lens adjusts the curvature of the lens by changing
voltage, so that the adjustment of the
focal length is realized; a reflecting mirror is arranged in the
tail end of the measuring rod and used for emitting a measuring
light beam from a side window at the
tail end to scan the inner contour side wall. The device is high in
measurement precision, high in speed, non-contact, high in adaptability and capable of improving the level of inner contour rotation scanning measurement.