An Etymological Dictionary of Astronomy and Astrophysics

1. To reveal, make known, make visible.
   

   2. In imaging, to subject, as to the action of light, or other electromagnetic radiations.

Etymology (EN): M.E. exposen, from O.Fr. exposer “lay open, set forth,” from L. exponere “set forth, lay open, exhibit,” with contamination from poser “to lay, place” (→ position). doublet of expound.

Etymology (PE): 1) Osnehâdan, from os-, → ex-,

• nehâdan “to put, place,” → position.
  

2. nur dâdan, from nur, → light

• dâdan “to give,” Mid.Pers. dâdan “to give;” O.Pers./Av. dā- “to give, grant, yield,” dadāiti “he gives;” cf. Skt. dadáti “he gives;” Gk. didomi “I give;” L. dare “to give, offer;”
  PIE base *do- “to give.”