Polarization-independent focusing is advantageously achieved by a multifocal system having a polarization beam splitter (PBS) to split an unpolarized light beam into two orthogonally linearly-polarized (LP) light beams. The two LP light beams are reflected by mirrors to travel in opposite directions and enter into a variable-focusing module at two ends thereof, respectively. The module includes waveplates to convert the LP light beams into two circularly-polarized (CP) light beams at both ends of an optical assembly. The optical assembly is formed with a stack of birefringent optical elements including at least one geometric phase lens and one polarization selector that may be electrically modulated to select the optical power in focusing the two CP light beams. Followed by the waveplates converting two focused CP light beams to two focused LP light beams and upon mirror reflection, the beams are finally recombined by the PBS to form one focused light beam.

In order to configure or produce an electrically controllable optical element on the basis of the electro-optic Kerr effect with a low threshold and operating voltage, a minimized temperature dependence of the effect and a low response time, the Kerr liquid according to the invention comprises a mixture of rod-shaped molecules and non-rod-shaped molecules as active composites, a thin layer having a pre-stamping, wide-mesh, anisotropic network between structured and/or planar conductive layer applied to a substrate thus configure a thin-film cell in such a way that without electric field the state of the active composite of the Kerr liquid in the working temperature region RT is isotropic and that by electrically continuous adjustment, of the voltage U or by a switching-on or switching-off a change the voltage U, in the optical element a voltage-induced phase shift or a refractive index deviation is generated and the light passes through an electrode gap perpendicular to the electrodes.

In order to configure or produce an electrically controllable optical element on the basis of the electro-optic Kerr effect with a low threshold and operating voltage, a minimized temperature dependence of the effect and a low response time, the Kerr liquid according to the invention comprises a mixture of rod-shaped molecules and non-rod-shaped molecules as active composites, a thin layer having a pre-stamping, wide-mesh, anisotropic network between structured and/or planar conductive layer applied to a substrate thus configure a thin-film cell in such a way that without electric field the state of the active composite of the Kerr liquid in the working temperature region RT is isotropic and that by electrically continuous adjustment, of the voltage U or by a switching-on or switching-off a change the voltage U, in the optical element a voltage-induced phase shift or a refractive index deviation is generated and the light passes through an electrode gap perpendicular to the electrodes.

A liquid photochromic filter for attenuating an image is disclosed. The liquid photochromic filter includes a photochromic dye in a liquid solution that is contained in a cavity defined by a housing with two optical windows. The liquid photochromic filter may be used in imaging system for sensing light in an area of high optical contrast. In some implementations, the imaging system is for monitoring a welding operation, whereby the liquid photochromic filter is used to reduce the intensity of the light observed from the welding arc.

A digital light path length modulator includes an optical path length extender (OPLE) and a polarization modulator. The OPLE has two light paths with different path lengths, such that the light having a first polarization is directed through a first light path, and the light having a second polarization is directed through a second light path.

switchable optical filter that is based on carrier injection induced semiconductor to metal phase transition (SMT) of vanadium oxide-based (e.g., VO.sub.2) thin films may reversibly change from optically transparent to opaque while undergoing such phase transition. Electrical carrier injection may be established by an electric field or by photoexcitation. The SMT may also be induced by a combination of applying an electric field and optical flux. Such a switchable optical filter, when inserted in the optical path of an optical radiation sensor, may be used to control and/or limit high power optical beams, such as a laser beam impinging on one or more sensor elements. Since the SMT may be configured to occur at ultrafast time scales (e.g., approximately 100 femtoseconds), it may also act as a beam shutter and/or as a fast optical beam modulator.

An electro-chemical device having a cell thickness of 1 μm-1000 μm, comprising a first and a second substrate disposed to face each other, and having electrodes on facing surfaces, transparent electrolyte solution sandwiched between the first and the second substrates, containing electro-deposition material containing Ag, mediator, supporting electrolyte, and solvent, and having optical density not larger than 0.1 in visible light range of wavelength 400 nm-800 nm.

The technology of a zero loop-area oblique-incidence Sagnac interferometer and methods of using the Sagnac interferometer to detect magneto-optic Kerr effect is disclosed. An example apparatus includes: a light source configured to generate an optical beam; a beam splitter; a polarizer configured to separate the optical beam into two orthogonal components; a modulator configured to phase-modulating at least one of the two orthogonal components to produce a modulated pair of orthogonal components; a polarization dependent delay optics configured to direct the modulated pair of orthogonal components toward a surface of a sample to cause the modulated pair of orthogonal components to incident on the surface at an oblique angle; a mirror configured to reflecting the modulated pair of orthogonal components back towards the beam splitter; a photo receiver configured to receive a return beam redirected by the beam splitter; and a phase-sensitive detector.

The technology of a zero loop-area oblique-incidence Sagnac interferometer and methods of using the Sagnac interferometer to detect magneto-optic Kerr effect is disclosed. An example apparatus includes: a light source configured to generate an optical beam; a beam splitter; a polarizer configured to separate the optical beam into two orthogonal components; a modulator configured to phase-modulating at least one of the two orthogonal components to produce a modulated pair of orthogonal components; a polarization dependent delay optics configured to direct the modulated pair of orthogonal components toward a surface of a sample to cause the modulated pair of orthogonal components to incident on the surface at an oblique angle; a mirror configured to reflecting the modulated pair of orthogonal components back towards the beam splitter; a photo receiver configured to receive a return beam redirected by the beam splitter; and a phase-sensitive detector.

Provided are a laser annealing apparatus and a method of manufacturing a substrate having a poly-Si layer using the laser annealing apparatus. The laser annealing apparatus includes a laser beam source that emits a linearly polarized laser beam, a polygon mirror that rotates around a rotation axis and reflects the laser beam emitted from the laser beam source, a first Kerr cell disposed on a laser beam path between the laser beam source and the polygon mirror, and a first optical element that directs the laser beam reflected by the polygon mirror toward an amorphous Si layer where the laser beam is irradiated upon the amorphous Si layer.