OPTICAL RANGE FINDER BASED ON POSITION SENSITIVE DETECTOR

A caster structure including a seat body, a linking member, a caster seat and a lower bearing cover. The linking member is integrally formed with an upper bearing cover. The seat body is formed with a differential fixing hole and the top of the linking member is formed with a fixing section. The shape of the cross-section of the fixing section is an internal tangential circle of the differential fixing hole. When the fixing section is passed through the fixing hole and compressed and fixedly riveted, the fixing section will form a differential section complementary to the fixing hole. Accordingly, the linking member is firmly connected with the seat body without rotation.