Question

The component in an optical instrument used to increase the angular object field and to minimize aberrations is called as ___________

(a) Objective lens

(b) Eye lens

(c) Field Lens

(d) Plano-concave lens

I had been asked this question in a national level competition.

The origin of the question is Optical Instruments in portion Optics of Engineering Physics II

Answer 1

The correct option is (c) Field Lens

To elaborate: Field lens is placed between the objective and the eye lens. It increases the field of view and brightness of the image. It helps in reducing the aberrations in the lens. It brings the center of the exit pupil near the eye lens. Together, the field lens and the eye lens constitute an eyepiece or ocular.