Avantra 30 2400dpi dots not sharp,clear

[Buchu]

Hi everyone,
i am asked to calibrate an avantra 30 imagesetter for the 2400 dpi resolution.first i imaged the exposure test from the image setter itself and i found exposure value of 200 is the correct exposure|(i measured using denisitometer and found 200 to be ok) but the dots are kind of foggy not clear and sharp.i tried to calibrate from the rip(xitron navigator7 ) i am getting inconsistent results.i want to resolve the dot issue first do i have to check and test the focuser parameters?or could it be a laser problem ? has anyone faced same issue please reply
thanks

 

[VladCanada]

After cleaning the spinner mirror your problem will disappear.
Use Avantra internal test exposure value to find optical density about 4.0D only, not for %%.
Dont try to reach 50% decreasing exposure, use RIP calibration for that purpose.