I was able to get what i needed.
I used the tip from ic-racer. The glass surface of the lens was reflecting much of the room. (white ceiling, white bookshelves, brass lamps). That was one obstacle. I ended up using a black card to mask out the reflections.
Then I used a focused beam from a LED light to illuminate the inside of the lens.
Finally I found i had to use manual focus so the camera would stop focussing on the front of the lens and focus exactly on the imperfections.
Thanks all.