Question

what is this device?
camera obscura
camera lucida
optical lens
optical mirror

Explanation:

Camera Lucida is a device that allows an artist to see the image of an object superimposed on the drawing surface, helping with accurate drawing. It has a prism - like structure and is different from Camera obscura (a dark - box device for projecting an image), optical lens (a simple refractive element), and optical mirror (a reflective element). The device in the image is a Camera Lucida.

Answer:

Camera Lucida