why we use composed lentiform in optical science?

[pedram]

why we use composed lentiform in optical science?

[Kurdt]

why we use composed lentiform in optical science?

I am taking a guess here and assuming you are asking why we use compound lenses in optical instruments. This is to reduce or null the effects of chromatic abberation which is inherent in all lenses made from any optically transparent material as refractive index is a function of wavelength. thus a compound lens focuses all colours at a singlt point and you get an image without any coloured fringes.

I hope this answers your question.