rotary voice coil detect linear displacement

{"cid":"91219913","title":"High Speed Rotary Voice Coil Motor Linear Optical Voice Coil Actuator For Valve Field","imgUrl":"https:\/\/img.chinax.com\/nimg\/41\/89\/f3bf6d3ecf1b308fa29cd426a191-200x200-1.jpg","attrs":{"Price":"$130.00\/pieces >=1 pieces","Brand Name":"SUPT","Model Number":"VARS0008-026-00A","Minimum Order Quantity":"\u22651","Delivery Time":"sample order 2-3 days,other one work days, bulk to be negotiated","Place of Origin":"Jiangsu, China","Packaging Details":"in carton and as customer requirements
Linear voice coil actuator","Supply Ability":"8000 Piece\/Pieces per Month Linear voice coil actuator","Certification":"ce,ISO9001","Payment Terms":"T\/T","Warranty":"3months-1year","Usage":"BOAT, Car, Electric Bicycle, UAV,3D Printing,Microscope,Robot,Medical Ventilators,Optical project","Type":"Micro Motor","Torque":"Requests","Construction":"Permanent Magnet","Commutation":"Brush","Protect Feature":"Totally Enclosed","Speed(RPM)":"Variable Speed","Continuous Current(A)":"Current","Efficiency":"IE 1","Peak torque":"0.08N-M","Continuous torque":"0.045N-M","Max travel":"26mm","Rated Voltage":"6.4V","Width * height":"39.8*26.1mm","Port":"Shanghai Port"}}

{"cid":"91225856","title":"M12xP0.5 Mount Voice Coil Motor Metal Construction VCM For Fast And Precise Autofocus","imgUrl":"https:\/\/img.chinax.com\/nimg\/57\/d0\/26b96149829a53aa4b4b3753f5cb-200x200-1.jpg","attrs":{"Price":"$8-12 \/ piece","Brand Name":"CCHT","Model Number":"04-006-013","Minimum Order Quantity":"100 pieces","Delivery Time":"1-4WEEK","Weight of adaptive lens":"8g Max.","Coil resistance":"32\u03a9\u00b15(at 25\u2103)","Rear Focal Length(RFL)":"2~8mm","Payment Terms":"T\/T&ID card","Dimensions":"22.2x 22.2x 14.6mm","Torque of adaptive lens":"60~600gf-cm","Place of Origin":"Sichuan, China","Mount":"M12xP0.5","Packaging Details":"CARTON","Rated current":"\u2264120mA","Test environment temperature":"25\u00b15\u2103","Product name":"Heavy Load Metal Frame M12 Voice Coil Motor","Feature":"High load capacity, compatible with heavy optical lens","Weight of motor":"12.6g"}}

{"cid":"91220132","title":"1500W RMS PW18F Pro Audio 18 Inch Subwoofer with 4 Inch Voice Coil for High Energy FERRITE Magnetics","imgUrl":"https:\/\/img.chinax.com\/nimg\/4c\/2b\/2da508e3f0b2e1622cabf5e4d4f7-200x200-1.jpg","attrs":[]}