A pattern projection apparatus is suitable for using with an endoscope is provided. The pattern projection apparatus includes at least one light source. The light source is suitable for providing a light beam transmitted to an observation surface. A pattern is formed on the observation surface where the light beam transmitted to the observation surface. In addition, a dimension of the pattern on the observation surface is fixed. Furthermore, the dimension of the pattern keeps the same when a distance between the light source and the observation surface changes.一種圖樣投影裝置，適於搭配內視鏡使用。此圖樣投影裝置包括至少一光源。此光源適於發出傳遞至觀察面的光束，其中光束於觀察面上形成圖樣。另外，位於觀察面上的圖樣之尺寸固定，且不隨光源與觀察面之間的距離改變而改變。
