Acronis can image and restore a RAID. There is no need to image the drives seperately. of course you will need to recreate the raid array before restoring the data to it.
...and as TyrOd sated, It's the same way you image any partition/volume.
Step by step? It's pretty simple... backup -> full backup -> Select source (array) -> select destination -> start. You should be able to leave everything at defaults, at least that how it worked in Acronis 2012 and earlier.
Also, be sure to create an Acronis rescue disk. After creating it, boot from it and make sure it detects your RAID properly otherwise your backup/image will be useless.