An illuminating device includes a light source and a light-pattern generating member. The light source emits an incident light. The light-pattern generating member is disposed on a side of the light source to receive the incident light. The incident light passes through the light-pattern generating member so as to generate a transmission light. The transmission light generates a light pattern. A light intensity distribution is formed by the light pattern, and a light intensity near the light source is equal to a light intensity far from the light source.
