camera lucida

Camera lucida in use A camera lucida is an optical device used as a drawing aid by artists and microscopists. By looking through the prism in its standard, a user sees an optical superimposition of the subject positioned in front of the device over the surface below. This allows the artist to duplicate key points of the scene on the drawing surface, thus aiding in the accurate rendering of perspective.

Camera Lucida or Drawing Prism for Biological Microscopic DrawingA camera lucida is somewhat similar mechanism as a periscope. However it completes two total internal reflections, generally within a single glass parallellopiped or rhomboid glass that works as a double prism.