Fig. 2.

Increasing the size of the laser beam on the retina to circumvent safety problem. The size of the laser spot on the retina in the eye model with (c) and without (b) dynamic phase modulation. (a) A sample arm – part of the setup shown in Fig. 1 – and an eye model. It demonstrates how a laser beam is focused on the retina in the coherent (DM OFF) and incoherent (DM ON) cases. For the eye model, an achromatic doubled (f = 19 mm) was used. An image of the focused spot was recorded by a camera placed at the focal plane of the lens corresponding to the retina plane in the eye model when DM was switched OFF (b) and ON (c). The size of the focused spot was ∼ 12 µm in (b) and was broadened to 358 µm in (c), as can be seen from the line profiles, shown in (d). The illumination radius increase is ∼30 times, and the area – 890 times – greatly reducing the laser intensity on the retina.