The invention relates to a Bragg mirror comprising a portion (110) of ribbon (100) having a refractive index n1, corrugations (112) having a refractive index n3 and a separation layer (111) separating the ribbon (100) from the corrugations (112) and having a refractive index n2, such that n2<n3 and n2<n1. The invention also relates to a method for producing such a mirror.

A decoding device for an absolute positioning code is provided. The decoding device includes a linear feedback shift register (LFSR), a lookup table (LUT) circuit, a counter circuit, and a computation circuit. The LFSR includes n registers, for loading the absolute positioning code with a first frequency. The LFSR performs shifting operation according to a clock signal having a second frequency greater than or equal to the first frequency. The LUT circuit outputs a lookup result and a valid flag according to values stored in the n registers. The lookup result has k different data, k≦(2.sup.n−1). The counter circuit resets according to the valid flag, and performs counting operation according to the clock signal to generate a counting result. The computation circuit performs calculation according to the lookup result and the counting result to generate a decoding result when the valid flag indicates valid.

An optical element includes a substrate, an intermediate layer, a topmost layer, and a contiguous multitude of recessed and non-recessed areal regions. The intermediate layer is formed over a top surface of the substrate and has a refractive index n.sub.I. The topmost layer is formed directly on the intermediate layer and has a refractive index n.sub.T where n.sub.T≠n.sub.I. The intermediate and topmost layers are substantially transparent over an operational wavelength range that includes a design wavelength λ.sub.0. A subset of areal regions has a largest transverse dimension less than about λ.sub.0. Each non-recessed areal region includes corresponding portions of the intermediate and topmost layers. Each recessed areal region extends entirely through the topmost layer and at least partly through the intermediate layer. A fill medium fills the recessed areal regions. The areal regions are variously sized and distributed transversely across the optical element.

Directionally dependent optical effects are produced from faceted micrometer-scale substructures. The directionally dependent optical effects can appear as one specific color when viewed from one direction and another specific color when flipped and viewed from the opposing direction. The directionally dependent optical effects may appear reflective or transmissive from one direction and antireflective or opaque when flipped around.

A capacitance type rotation angle detection stage light includes a pivoting member and a supporting member for supporting the pivoting member. A reflecting grating is attached on the pivoting member, and the reflecting grating rotates along with the pivoting member. A signal grating is attached on the supporting member. The signal grating and the reflecting grating are arranged oppositely. The signal grating comprises capacitance emitting pieces, a capacitance receiving piece and shielding pieces. The reflecting grating comprises capacitance reflecting pieces that reflect signals sent from the capacitance emitting pieces to the capacitance receiving piece. Periodic excitation signals applied to the capacitance emitting pieces finally form a composite signal on the capacitance receiving piece through coupling of two pairs of capacitors that the capacitance emitting pieces and the capacitance reflecting pieces, and the capacitance reflecting pieces and the capacitance receiving piece.

In a spectroscopic module 1, a flange 7 is formed integrally with a diffraction layer 6 along a periphery thereof so as to become thicker than the diffraction layer 6. As a consequence, at the time of releasing a master mold used for forming the diffraction layer 6 and flange 7, the diffraction layer 6 formed along a convex curved surface 3a of a main unit 3 can be prevented from peeling off from the curved surface 3a together with the master mold. A diffraction grating pattern 9 is formed so as to be eccentric with respect to the center of the diffraction layer 6 toward a predetermined side. Therefore, releasing the mold earlier from the opposite side of the diffraction layer 6 than the predetermined side thereof can prevent the diffraction layer 6 from peeling off and the diffraction grating pattern 9 from being damaged.

One or more excitation energy sources emit light in an excitation spectrum and direct the emitted light as an excitation beam to the emitting surface of a wavelength conversion element directly or via reflection. Distinct areas of the emitting surface are coated with one or more distinct fluorescent phosphors. The phosphor-coated areas receive the excitation beam and generate a sequence of fluoresced light beams at a light output, each fluoresced beam of a narrow spectrum determined by the type of phosphor and the excitation spectrum. The fluoresced beams travel parallel to an emitting axis at a non-zero angle to axes associated with the excitation beams.

A display body includes lattice lines that are arranged along a plane of incidence on which light is incident. The lattice lines have properties for forming a bright image with diffracted light of the incident light in an oblique view in which the plane of incidence is viewed obliquely, and absorbing some of the incident light. The surface of each of the lattice lines includes dispersed fine step parts that are repetitive in the direction in which the lattice lines extend. The steps have an antireflection function and form a dark image in a front view directly facing the plane of incidence.

A grating-coupled light guide includes a plate light guide and a grating coupler at an input to the plate light guide. The grating coupler is to receive light from a light source and to diffractively redirect the light into the plate light guide at a non-zero propagation angle as guided light. Characteristics of the grating coupler determine a spread angle of the diffractively redirected guided light.

A curved diffraction grating includes a substrate and a metal layer. The substrate is a two-dimensional curved plate structure and has a first surface, a second surface and a plurality of microstructures. The first surface is disposed opposite to the second surface, and the microstructures are disposed on the second surface. Each of the microstructures is a saw-tooth structure and has a clear blazed angle. The metal layer is disposed on the microstructures and has a plurality of diffraction structures corresponding to the microstructures. A spectrometer containing the curved diffraction grating and a manufacturing method of the curved diffraction grating are also disclosed.