To prevent effectively the flickering of an image due to the switching of a polarization direction while reducing speckle noise. A polarization switching unit is provided in an optical path of laser light to a projection surface A and periodically switches a polarization direction of the laser light emitted therefrom between p and S polarization. A laser control unit controls laser light sources in synchronization with the switching by the polarization switching unit and determines a driving current corresponding to a grayscale to be displayed on the basis of driving current characteristics for P polarization when the polarization direction of the laser light is the P polarization. In addition, the laser control unit determines the driving current corresponding to the grayscale to be displayed on the basis of the driving current characteristics for P polarization when the polarization direction of the laser light is the S polarization.

A wire grid polarizer and method of making a wire grid polarizer can protect delicate wires of the wire grid polarizer from damage. The wire grid polarizer can include a protective-layer located on an array of wires. The array of wires can further be protected by a chemical coating on an inside surface of the air-filled channels, closed ends of the air-filled channels, damaged wires of the array of wires in a line parallel to an edge of the wire grid polarizer, or combinations thereof. The method can include (i) providing the wire grid polarizer, (ii) applying the protective-layer, by physical vapor deposition or chemical vapor deposition but excluding atomic layer deposition, onto the array of wires, (iii) cutting the wire grid polarizer wafer into multiple wire grid polarizer parts, then (iv) protecting the array of wires.

Devices and methods are described herein that use a first solid figure element, a polarizing beam splitter, and a second solid figure element to reduce speckle in projected images. Specifically, laser light is generated and split into two portions having orthogonal polarizations. The first portion of laser light is internally reflected off at least three internal faces of the second solid figure element and is then spatially recombined with the second portion of laser light in the first solid figure element. The difference in path length followed by the two portions generates a temporal incoherence in the recombined laser light beam, and that temporal incoherence reduces speckle in the projected image.

Devices and methods are described herein that use birefringent elements to reduce speckle. The birefringent elements are angularly separate received laser light into two separated light beams, and then recombine the two angularly separated light beams. At least one scanning mirror is configured to reflect the recombined laser light beam, and a drive circuit is configured to provide an excitation signal to excite motion of the at least one scanning mirror. The angular separation of the light beams generates a relative delay between the two light beams, and this relative delay between light beams generates a temporal incoherence in the recombined light beams. This temporal incoherence can reduce speckle in the projected image.

The disclosure generally relates to beamsplitters useful in color combiners, and in particular color combiners useful in small size format projectors such as pocket projectors. The disclosed beamsplitters and color combiners include a tilted dichroic reflective polarizer plate having at least two dichroic reflective polarizers tilted at different angles relative to incident light beams, with light collection optics to combine at least two colors of light.

A phase difference compensating element that can effectively compensate polarization disturbance, and a projection-type image projecting device are provided. The phase difference compensating element includes: a birefringent layer formed with a film stack of obliquely-deposited films, each of the obliquely-deposited films having a thickness equal to or smaller than the used wavelength; and an Rd-AR film that is formed with a film stack of two or more kinds of dielectric films having different refractive indexes, and provides an arbitrary phase difference to a phase difference in obliquely-incident transmitted light in the birefringent layer. The phase difference Rd to be provided by the Rd-AR film satisfies 1<Rd(λ)/Rd(λ′)<1.5 (λ<λ′), at an arbitrary wavelength λ in the used wavelength band and within an incident light angle range of 0 to 25 degrees.

A projection device comprises a light source, a first attenuator and a second attenuator, a first driver, a second driver, a light receiving element, and a controller. The light source emits light. The first attenuator and the second attenuator attenuate intensity of the light from the light source. The first driver drives the first attenuator. The second driver drives the second attenuator. The light receiving element receives the light distributed by the second attenuator. The controller controls the second driver to control the distribution ratio of the light distributed to the light receiving element by the second attenuator according to control of transmissivity of light at the first attenuator by the first driver.

A projection display unit with a detection function includes a projection display section (110) and a detector (120). The projection display section (110) includes a display light source. The display light source emits light used as illumination light, and projects an image onto a projection surface with the illumination light. The detector (120) includes a detection light source that emits detection light. The detector (120) detects an object on or near the projection surface, and outputs a power-saving instruction signal to the projection display section (110) in accordance with a detection state of the object. The power-saving instruction signal instructs a transition to a power-saving mode. The projection display section (110) turns off the display light source in response to the power-saving instruction signal.

In some embodiments, a polarizing beam splitter is provided. The beam splitter may comprise an optically transmissive spacer having first and second opposing faces, with a first polarizer on the first opposing face and a second polarizer on the second opposing face. The optically transmissive spacer may separate first and second triangular prisms of a cube-type beam splitter, with the first polarizer between the first triangular prism and the first opposing face of the spacer, and the second polarizer between the second triangular prism and the second opposing face of the spacer.

Optical systems, such as 2-D and 3-D projection systems, may be configured to have a compact back focal length to allow for more compact projection lenses, lower throw ratios, improved contrast, or any combination thereof. In an embodiment, an optical system may include a relay element configured to form an intermediate image having a focal point proximate to a projection lens.