cheval glass vs imager

cheval glass

noun
  • A long mirror, mounted on a swivel in a frame, allowing it to be tilted. 

imager

noun
  • A system that creates a digital copy such as a disk image. 

  • One who images or forms likenesses; a sculptor. 

How often have the words cheval glass and imager occurred in a corpus of books? (source: Google Ngram Viewer )