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Phone:1-800-222-6440Fax:1-949-253-1680Email:sales@newport.
comWeb:newport.
comTECHNICALAPPLICATIONNOTEAgilisFamily–StepSize.
vsActualMotionDS-08096OneofthemostfrequentlyaskedquestionsabouttheAgilisfamilyofproductsis:"WhatistherelationbetweenthestepsizeandtheactualmotionoftheAgilisdevice"Inordertobeabletoanswertothisquestion,weneedtofirstunderstandthatthestepsizeofanAgilisdeviceanditsstepamplitudearetwodifferentthings.
ThestepsizeofAgilisproductsisnotrepeatable.
Itvariesfrommounttomountanditdiffersbetweenforwardandbackwardmotion.
Itsomehowremindsusofhumansteps,whichvariesbetweentallandshortpeople,tiredandfreshpeople,athleticandnon-athleticpeople,theloadthatisbeingcarriedduringthemotion,etc.
Althoughthestepsizeisadjustable,wecannotforecasttherelationbetweenstepamplitudeandstepsizeforanindividualmount.
Soourcustomerswillneedtomeasurethestepsizeforadefinedstepamplitudeontheirown.
Hereisasimpleproceduretomeasurethestepsizeforanapplication,whereitisrequiredtorotatethepolarizerwithanAgilisdevicetoadjustthepowerofalaser:1.
Adjusttherotatorfor100%transmission.
2.
SendcommandZPtozerotheposition(thisisnowthereferencepoint)3.
SendcommandSUtosetthedesiredstepamplitude(theamountofthevoltageappliedtothemotor.
Maximumvalueis50)4.
SendsuccessivePRcommandsandrecordthepoweraftereachstepuntil0%transmissionisreached(itisrecommendedtostartwithalargenumberofPRsteps,thenmakethemsmallerastheygetclosertothe0%transmission).
Note:alwaysmoveinthesamedirection,notbackandforth.
5.
At0%transmissionthepolarizerhasbeenmovedby45°.
6.
SendTPcommand.
45°dividedbytheresultoftheTPcommandistheaveragestepsizeinthatdirectionforthismount,inthisconfigurationandforapre-definedstepamplitude.
7.
Repeatthesameprocedurefortheotherdirectionofthemotion,sincethestepsizevariesbetweenforwardandbackwardmotion.
8.
Forareliableprocess,thisprocedureneedstoberepeatedfromtimetotime,sincethestepsizewillchangeovertime.
9.
Forbestpracticeitisrecommendedtoalwaysreadthepowerfromasensor.
Inthatcasewedon'treallycarewhatthestepsizeisandonlyadjustuntilthedesiredvalueisreached.
ForAgilisdeviceswithlimitswitchesfindingtheapproximaterelationbetweenthestepsizeandtheactualmotioninmmordegreesisaloteasieranddoesn'trequireanyexternaldevices(formoredetailsonaprocesspleaseseethedescriptionofMVcommandinAgilismanual)