U.S. Pat. Nos. 7,641,345 and 8,057,045 to Johnson describes a projection apparatus for generating a moving star field and a cloud-like effect comprises a means for generating a cloud-like effect using at least one non-coherent light source, a means for generating a moving star field using at least one coherent light source and a means for regulating and supplying electric power. The means for generating cloud-like effect using at least one non-coherent light source comprises at least one pair of condenser lenses and an interferential filter wheel rotated by a motor, disposed between at least one pair of condenser lenses. The means for generating the moving star field using a coherent light source comprises a grating wheel rotated by a motor and a diffractive optical element disposed between the at least one coherent light source and the grating wheel.
U.S. Pat. No. 8,100,537 to Johnson describes a laser landscape lighting apparatus for use in accent lighting applications for landscapes and outdoor venues. In one embodiment, the laser landscape lighting apparatus includes a coherent light source in combination with a diffractive optical element and optionally a diffraction grating wheel. The diffractive optical element may be, for example, a holographic optical element. In some embodiments, the laser landscape lighting apparatus includes a temperature-controlled integral derivative system. In one application, the laser landscape lighting apparatus may project a static or movable star field.