Parallax barriers are a kind of diffraction grating that interweaves transparent and non-transparent lines. When viewers watch through the grating, their left and right eyes see different images, creating a 3D effect.
普通的光學眼鏡，不需通電即可啟動，每副售價僅在數美元至十美元間，又稱「被動式偏光電視」。