Lens and light source module

A light source module comprising:

• a light source;
• and
• a lens, the lens comprising:
• a light incident surface facing the light source;
• a first light emitting surface, the first light emitting surface being a Fresnel surface and opposite to the light incident surface, the first light emitting surface comprising a plurality of concentric annular surfaces and a first border intersecting with some of the concentric annular surfaces, the first light emitting surface and the light incident surface cooperatively forming a Fresnel lens portion with an optical axis;
• and
• a second light emitting surface located at a side of the first light emitting surface adjacent to the first border, an angle formed between any tangent plane of the second light emitting surface and a plane perpendicular to the optical axis being smaller than an angle formed between any tangent plane of the concentric annular surfaces passing any point on the first border and the plane perpendicular to the optical axis.