Deep hole measuring device and measuring method

The invention belongs to the field of mechanical manufacturing deep hole detection, and particularly relates to a deep hole measuring device and a measuring method. The measuring device comprises a measuring body and a calculating unit, the measuring body comprises a centering device, an imaging device, a screen, a light passing plate, a light barrier and a light source which are sequentially and fixedly arranged on the centering device through a connecting mechanism, and the light barrier and the light passing plate are light-proof circular plates which are coaxially arranged with the centering device; the light-passing plate is provided with an annular light-passing gap concentric with the axis of the centering device, the light source is used for emitting light to illuminate the inner wall of a workpiece to be measured, and light scattered by an illuminated area is blocked by the light-blocking plate, passes through the light-passing gap in the light-passing plate and then is imaged on a screen. The calcul