The 3 types of lenses are:Convex lens: 1.1 Convex lens is thicker at the centre and gets thinner towards the edges. 1.2 This lens converges a straight beam of light. ... Concave lens: 2.1 concave lens is thinner at the centre and gets thicker towards the edges. 2.2 This lens diverges a straight beam of light. ... Plano lens: