the square light pattern rectangular light pattern and curved light pattern produced by surface structured diffusion plates 30 having those different microstructures 40 respectively in the embodiment shown in fig1 a to fig1 d and fig1 a to fig1 b wherein the light pattern 200 is a curved light pattern increasing the width w of each microstructure 40 indicated by the arrow in fig1 a shortens and thickens the curved light pattern and increasing the depth h of each microstructure 40 indicated by the arrow in fig1 b elongates and thickens the curved light pattern this also helps to show that different light patterns can be produced by only replacing different surface structured diffusion plates 30 according to practical needs this further demonstrates that the light pattern 200 of the lamp structure 100 of an adaptive streetlight can be modified by choosing the desired microstructures 40 for the surface structured diffusion plate 30 by changing the shape of the microstructures 40 a light pattern suitable for the intended application can be obtained thus not only can the lamp structure 100 of an adaptive streetlight effectively concentrate confine and evenly project the light of the streetlight to the target area but also the microstructures 40 can be modified to effectively control the light output angle according to the shape of the road to be illuminated in order to produce a particular light pattern 200 that conforms to the shape of the road fig1 a and fig1 b respectively show a side sectional view of the surface structured diffusion plate 30 in an embodiment.