一种三維投影设备包含光源模块、光调制器、光学模块与镜头模块。光源模块依时序提供具有不同偏转角度的光束。光调制器将光束依时序调制成复合影像。光学模块将光束导引至光调制器，将复合影像导引至镜头模块。镜头模块包含分合光棱镜组、第一空间滤光组件、第二空间滤光组件与镜头。分合光棱镜组具有入光面、出光面、第一中继面与第二中继面且包含双面反射片，置于第一与第二中继面之间。光学模块置于入光面。第一空间滤光组件与第二空间滤光组件分别置于第一与第二中继面，分别将复合影像依时序滤为第一影像与第二影像。镜头置于出光面。

An autostereoscopic projection device includes an illuminating module, a light modulator, an optical module, and a lens module. The illuminating module is configured for providing light beams with different deflection angles in sequence. The light modulator is configured for modulating the light beams into compound images in sequence. The optical module is configured for guiding the light beams to the light modulator, and guiding the compound images to the lens module. The lens module includes a beam separation prism group, a first spatial filter, a second spatial filter and a lens. The beam separation prism has an incident surface, a light emitting surface, a first relay surface, and a second relay surface and includes a double-side mirror disposed between the first relay surface and the second relay surface. The optical module is disposed at the incident surface. The first spatial filter and the second spatial filter are respectively disposed at the first relay surface and the second relay surface, and are respectively configured for filtering the compound images to be first images and second images in sequence. The lens is disposed at the light emitting surface.