A lens blocking device is disclosed that includes a frame, a light source mounted on the frame, a carriage having a first end and a second end mounted on the frame for sliding movement between first and second positions, a first mirror mounted on the carriage first end and a lens block holder mounted on the carriage second end and shiftable between third and fourth positions with respect to the carriage, a stage disposed between the light source and the carriage, and including an opening, for supporting an object, an at least partially translucent screen generating a display image operably connected to the support frame, at least one second mirror arranged to reflect an image of an object on the stage from the first mirror, when the carriage is in the first position, onto the screen, and an actuator operably connected to the carriage. The actuator shifts the carriage between the first position and the second position and shifts the block holder between the third position and the fourth position, and the display image on the screen is superimposed over an image of the object on the stage when the carriage is in the second position.