Provided is a multi-layer light guide apparatus. Various optical paths are formed as a light source emits light into the apparatus. Main structure of the apparatus includes a body and a micro-structured layer. The body has a first layer with first refractive index (n1) and a second layer with second refractive index (n2). The first layer has a first critical angle (θC1). An interface critical angle (θC12) is formed between the associated first layer and second layer. The light then outputs as the light propagates through the layers. The micro-structured layer is formed on a side of the body. It features: n1 θC12;0