An accurate measuring system for VTR magnetic track

A new design has been presented and the corresponding measuring system has been built, which is used to calibrate the servomechanism of a video tape recorder (VTR), to test the assembling errors of the video head drum assemblies of a VTR and to determine exchangeability of a VTR. This design is based upon the principle of the method of Bitter pattern, the digital image processing technology and the precise electromagnetic micromotion device (PEW). The accuracy of the former system lies on the location accuracy of the specimen stage of a measuring microscope and that is about 0.5-1 um. And in our system the measuring precision depends on the amplification of system and the resolution of the digital image processing interface, so it is possible to improve the measuring accuracy of the system to deep submicrometer. As a result, the distance measuring precision of our measuring system has attained to 0.2 um.