imager vs speculum

imager

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

  • One who images or forms likenesses; a sculptor. 

speculum

noun
  • A mirror, especially one used in a telescope. 

  • A lookout place. 

  • A bright, lustrous patch of colour found on the wings of ducks and some other birds, usually situated on the distal portions of the secondary quills, and much more brilliant in the adult male than in the female. 

  • A medical instrument used during an examination to dilate an orifice. 

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