Which part of the RCO is used for reflecting the image to the eye?

Which part of the RCO is used for reflecting the image to the eye?

• A. Eyepiece
• B. Roof prism
• C. Objective lens
• D. Mirror

Answer: (B)

Light from the scene travels through the objective lens to form an image, and that image must be redirected and oriented so you see a correct, upright view through the eyepiece. The roof prism is designed to do this inside compact optical devices like the RCO: it uses internal reflections along a roof-shaped edge to fold the light path and rotate the image back to upright, then sends it to the eyepiece for viewing. This dual role of reflecting and erecting the image makes the roof prism the best choice for delivering the image to the eye. The eyepiece simply magnifies what the prism provides, while the objective lens forms the initial image; a mirror could reflect light but wouldn’t reliably correct orientation and keep the design compact.

Light from the scene travels through the objective lens to form an image, and that image must be redirected and oriented so you see a correct, upright view through the eyepiece. The roof prism is designed to do this inside compact optical devices like the RCO: it uses internal reflections along a roof-shaped edge to fold the light path and rotate the image back to upright, then sends it to the eyepiece for viewing. This dual role of reflecting and erecting the image makes the roof prism the best choice for delivering the image to the eye. The eyepiece simply magnifies what the prism provides, while the objective lens forms the initial image; a mirror could reflect light but wouldn’t reliably correct orientation and keep the design compact.