Electronis unit and optical head is usually mounted separately As outlined by the necessities ensuing from crucial environmental conditions. Two or three toes off is a huge concern but for my works by using I do think a handful of mm could well be ok. Although I do not system https://www.eltegypt.com/News/newsdetails/%D9%83%D9%84-%D9%85%D8%A7-%D8%AA%D8%AD%D8%AA%D8%A7%D8%AC-%D9%85%D8%B9%D8%B1%D9%81%D8%AA%D9%87-%D8%B9%D9%86-%D8%AC%D9%87%D8%A7%D8%B2-%D9%82%D9%8A%D8%A7%D8%B3-%D8%A7%D9%84%D9%85%D8%B3%D8%A7%D9%81%D8%A7%D8%AA-%D8%A8%D8%A7%D9%84%D9%84%D9%8A%D8%B2%D8%B1/43