Abstract: Systems and methods for driving a display of MEMS devices are disclosed. In one embodiment, a display includes an array comprising a plurality of interferometric modulators, and a driving circuit coupled to said array, said driving circuit configured to provide actuation signals to drive said array based on a temperature of the display. In another embodiment, a method of driving an array having a plurality of interferometric modulators configured into a display is disclosed, where the method includes sensing the temperature at a predetermined location in display, communicating a signal based on the sensed temperature to a display driver, generating an actuation signal to drive said display based on the received signal, and providing the actuation signal to the array.

Abstract: A simulated eye is provided. The simulated eye comprises a main body comprising a front surface. An area is formed on the front surface for simulating pupil portion of an eye. A first ring portion is formed on the front surface and surrounds the area. The first ring portion is covered with a layer of reversible thermochromic material.

Abstract: A thermochromic optical filter incorporating quantum confinement devices is formed as multilayered composite film of semiconducting materials. A quantum well adjacent a barrier layer ensures proper confinement of charge carriers within the well. A transition wavelength (i.e., the energy/wavelength at which the filter becomes transparent) is established by selecting a quantum well material with a bandgap near the desired energy and a barrier layer material with a higher bandgap. For a given reference temperature (e.g., room temperature), the exact transition wavelength is fixed by the thickness of the quantum well. The quantum confinement energy is added to the bandgap energy to yield the transition energy. A thermal control system varies the temperature of the thermochromic filter to adjust the transition wavelength. Temperature changes affect both the bandgap and the quantum confinement energy, and thus the optical properties of the thermochromic filter.

Abstract: Disclosed is an array for modifying a wavefront of an optical beam (3) having a beam axis (15). Said array comprises an influencing unit (1) which can be introduced into the beam path of the optical beam (3) and a heat source (12) that generates a thermal pattern and acts upon the influencing unit (1). The influencing unit (1) is provided with at least one planar cooling plate (7a, 7b) that extends transversal to the optical axis (15) of the incident beam (3) and a fluid layer or gel layer (9) which has a two-dimensional expansion, is disposed on the cooling plate with a basal surface, and absorbs the heat of the heat source. The two-dimensional expansion is large enough to receive approximately the entire cross section of the beam.

Abstract: An optical module is configured with a combination of a single-mode oscillating light source and an optical filter. In this optical module, the single-mode oscillating light source outputs a single-mode, frequency-modulated signal. Further, the optical filter converts the frequency modulation to an amplitude modulation. And, the single-mode oscillating light source and the optical filter are packaged without active alignment on the same substrate. Accordingly, it is possible to realize an optical module in a simple and low-cost configuration by packaging the single-mode oscillating light source and the optical filter by passive alignment, without active alignment, on the same substrate, and by using a simple optical filter such as a waveguide ring resonator, which converts a frequency modulation to an amplitude modulation.

Abstract: An optical phase shifting plate includes: an optical substrate configured to change a refractive index for light which passes through the optical substrate by a thermooptical effect; a thin-film heater formed on a surface of the optical substrate; a wiring member disposed to be substantially perpendicular to the surface of the optical substrate; an intermediate member disposed between the optical substrate and the wiring member, the intermediate member having: a first surface that is substantially flush with a surface of the thin-film heater; and a second surface that is substantially flush with a surface of the wiring member and that is perpendicularly adjacent to the first surface, a first bonding wire which electrically connects the surface of the thin-film heater to the first surface of the intermediate member; and a second bonding wire which electrically connects the surface of wiring member to the second surface of the intermediate member.

Abstract: An optical modulation apparatus that performs optimum bias voltage control for optical modulation without using a pilot tone. A drive unit generates a drive signal by adding a bias voltage to an input data signal. A light modulation unit modulates input light output from a light source unit, in accordance with the drive signal, and outputs the results as optical signals. A forward monitoring unit monitors a forward signal of the light modulation unit and outputs the forward signal. A reverse monitoring unit monitors a reverse signal of the light modulation unit and outputs a reverse signal. A bias control unit controls the bias voltage so that a measured monitor ratio matches a target value of the ratio between the forward signal and the reverse signal, obtained when the operating point of the light modulation unit is in a predetermined position on its operation characteristic curve.

Abstract: The reflectivity and transmissivity of building and vehicle surfaces is maintained while employing partial, variable, selective, or asymmetric diffusers between a surface and an external light source such that the reflected light is diffused to produce a reduction in glare, while minimally effecting the specular or collimated transmission (if any) of light through the surface. Glare is also reduced by utilizing diffuser devices that reflect light in a temperature dependent manner.

Abstract: A material is disclosed which possesses at least two of the following characteristics: (a) is optically transparent at a wavelength in the range from about 1500 nm to about 1560 nm; (b) has a 1/n dn/dt greater than that of silicon, (c) has an extinction coefficient, k, less than 10?3. In certain preferred embodiments, the material has the following characteristics: (a) 1/n dn/dt greater than that of silicon, and (b) an extinction coefficient, k, less than 10?3 at 1550 nm. In another aspect, a material comprising semiconductor nanocrystals, wherein the semiconductor nanocrystals are capable of displaying thermo-optic effects in bulk form and being sufficiently non-absorbing at a predetermined wavelength to be optically transparent at that wavelength is disclosed. In a preferred embodiment, the predetermined wavelength is about 1550 nm. Thin film, optical filters, and devices are also disclosed.

Abstract: The present invention discloses a multilayer dielectric optical structure wherein one of the optical materials in the multilayer structure shows an optically isotropic state above and a birefringent state below a characteristic temperature Tc near the room temperature. The optical structure reflects a predetermined wavelength range of electromagnetic radiation above the Tc but allow the same to transmit through below the Tc. The predetermined wavelength can be the near infrared radiation from 700 nm to 2500 nm, and the optical structure rejects solar heat in warm summer days but admits the same to interior on a colder winter day.

Abstract: The present invention is directed to a composite having tunable radiation diffracting properties which includes a flexible, water-free polymeric matrix and a crystalline colloidal array of particles having a lattice spacing, the array being embedded in the polymeric matrix and the lattice spacing changing responsive to stress applied to the polymeric matrix, thereby causing the radiation diffracting properties to change, wherein the polymeric matrix, the lattice spacing and the radiation diffracting properties all return to their original state essentially immediately upon removal of the stress. The present inventive composite is preferably made by a process, which involves forming a preliminary hydrogel polymerized crystalline colloidal array (PCCA), dehydrating the PCCA, and then forming a final, encapsulating polymeric matrix.

Abstract: A structured sub-mount assembly is disclosed to support a hybrid assembly of tunable filters. The sub-mount assembly is constructed to provide a high thermal resistance path and high mechanical resonance frequency. Optionally, the structured sub-mount assembly includes a temperature-controlled phase adjust component disposed approximately midway between the two tunable filters. The structured sub-mount assembly may be part of a tunable laser or other application.

Abstract: By varying the spacing between two surfaces, one of which is disposed in front of the other, an interferometric modulator selectively creates constructive and/or destructive interference between light waves reflecting off the two surfaces. The desired spacing can be achieved by deforming one or both surfaces. A heating element associated with a particular surface causes the deformation by heating the material that forms one or both of the surfaces. By varying the amount of applied heat, the amount of deformation is varied, thus allowing the distance between the surfaces to be controlled and thereby creating constructive and/or destructive interference as desired.

Abstract: Ligand exchange of thermochromic, LETC, systems exhibiting a reversible change in absorbance of electromagnetic radiation as the temperature of the system is reversibly changed are described. The described LETC systems include one or more than one transition metal ion, which experiences thermally induced changes in the nature of the complexation or coordination around the transition metal ion(s) and, thereby, the system changes its ability to absorb electromagnetic radiation as the temperature changes.

Abstract: The invention relates to a micro-mechanical thermal structure for modulating a light beam and a method for manufacturing such a structure. The micro-mechanical structure comprises two layers of material with different thermal expansion coefficients in a first direction and a second direction respectively, in which the first direction is transverse to the second direction and the two layers comprise an oriented polymer and the director of the molecules of the oriented polymer of the first layer is transverse to the director of the molecules of the oriented polymer of the second layer. An array of such micro-mechanical structures may form a thermo-optical modulator for modulating light. The method comprises a step of providing a mold with an orientation-inducing layer to obtain a molecular orientation in a mono-meric state of liquid crystalline monomers and a step of fixing the molecular orientation by photo-polymerization.

Abstract: Ligand exchange of thermochromic, LETC, systems exhibiting a reversible change in absorbance of electromagnetic radiation as the temperature of the system is reversibly changed are described. The described LETC systems include one or more than one transition metal ion, which experiences thermally induced changes in the nature of the complexation or coordination around the transition metal ion(s) and, thereby, the system changes its ability to absorb electromagnetic radiation as the temperature changes. In accordance with one aspect of the present invention, a thermochromic system is disclosed comprising a first metal ion and a second metal ion and at least one ligand that complexes with the first metal ion to form a L?MLC and complexes with the second metal ion to form a H?MLC wherein an increase in temperature of the system results in a reversible net increase in its ability to absorb light energy in the 400 nm to 1400 nm range due to the ligand transferring from the first metal ion to the second metal ion.

Abstract: Ligand exchange of thermochromic, LETC, systems exhibiting a reversible change in absorbance of electromagnetic radiation as the temperature of the system is reversibly changed are described. The described LETC systems include one or more than one transition metal ion, which experiences thermally induced changes in the nature of the complexation or coordination around the transition metal ion(s) and, thereby, the system changes its ability to absorb electromagnetic radiation as the temperature changes. In accordance with one aspect of the present invention, a thermochromic device is disclosed comprising at least two thermochromic layers when each thermochromic layer includes a polymer, at least one transition metal ion, at least one H?L ligand capable of forming a H?MLC with the transition metal ion and at least one L?L ligand capable of forming an L?MLC with the transition metal ion.

Abstract: The thermally switched reflective optical shutter is a self-regulating “switchable mirror” device that reflects up to 100% of incident radiant energy above a threshold temperature, and reflects up to 50% of incident radiant energy below a threshold temperature. Control over the flow of radiant energy occurs independently of the thermal conductivity or insulating value of the device, and may or may not preserve the image and color properties of incoming visible light. The device can be used as a construction material to efficiently regulate the internal temperature and illumination of buildings, vehicles, and other structures without the need for an external power supply or operator signals. The device has unique aesthetic optical properties that are not found in traditional windows, skylights, stained glass, light fixtures, glass blocks, bricks, or walls.

Abstract: An optical material comprising an ionic liquid and a polymer gel including a light controlling material, wherein the polymer gel absorbs and/or releases the ionic liquid in accordance with a temperature change. Also provided is an optical element comprising two substrates and the optical material between the two substrates.

Abstract: Briefly, in accordance with one or more embodiments, a thermally controlled optical filter comprises a frame coupled to an etalon where the frame includes a resistive thermal device disposed on the frame to obtain thermal measurements of the etalon during operation. The frame may be generally L-shaped or generally square-shaped. The frame may include a fillet that is generally planar, generally beveled or trapezoidal, or generally circular in shape. A heater may be additionally disposed on the frame. The etalon and frame subassembly may be bonded to a micro hot plate that is capable of heating the etalon to an operational temperature.

Abstract: An optical metrological system having a heat-generating light source coaxially mounted near a heat-sensitive lens. The system uses a temperature sensor to monitor the lens temperature and a heating element to heat the lens such that the lens operating temperature is greater than a maximum operating temperature of the light source in order to stabilize the focal length of the lens.

Abstract: Disclosed is an external light shielding film. The external light shielding film comprises a transparent substrate; and an external light shielding pattern formed on a surface of the transparent substrate and including a plurality of external light shielding parts. Each of the plurality of external light shielding parts has a polymer resin and at least one color-changeable colorant. The color of the plurality of external light shielding parts may vary according to an external heat source or vary depending on an intensity of an external light source, thereby improving a contrast ratio in a bright room, and a specific color may be visible even when the power of the display apparatus is OFF, thereby achieving an interior decorative effect.

Abstract: A method and circuit is disclosed for a laser system wherein the power of the laser signal is kept at a constant near optimum value and a portion of an frequency doubled output signal is monitored and detected so that noise within the frequency doubled output signal can be minimized. A feedback signal is used to dither the temperature of a frequency doubled crystal so as to minimize the noise in the frequency doubled output signal.

Abstract: We present an invention on the synthesis of elastic, bio-compatible functional microstructures wherein the designed electrical functionalities are achieved by mixing conducting nano to micro-particles with PDMS gels. The methodology for constructing planar and three-dimensional microstructures by soft-lithographic technique is presented. Applications such as electrodes, conducting strips, two and three-dimensional microstructures for electrical wiring connections, micro heaters, micro heater arrays, flexible thermochromic displays, and applications for microfluidic devices are demonstrated, all with demonstrated elastic flexibility and fall-proof characteristics while maintaining their functionalities. Results obtained are very promising for the utilization of such composites in future micro-fabrications, especially for the bio-chips and microfluidic devices.

Abstract: Systems and methods for driving MEMS display elements are disclosed. In one embodiment, a display comprises an array of MEMS display elements, and a driving circuit coupled to said array, wherein said driving circuit configured to provide at lease a row signal and a column signal to drive said array, and only one of said row and column signals is adjusted for temperature change. In another embodiment, a method of driving an array of MEMS display elements is disclosed, where the method comprises sensing a temperature at a predetermined location, generating one of a row signal and a column signal having a level based at least in part on the sensed temperature and the other not based on the sensed temperature, and providing said row and column signals to said array.

Abstract: An optical mount (1) for optical component (2) which has a edge contour (4) relative to extending radially optical axis (A), includes a rigid optical support (3) having an axially oriented stop edge (5), which is suitable for an axial contact with the optical component (2), and at least one flexible spring element which is arranged radially outside the stop edge (5), extends axially on the component side and is curved radially inward. The radial spring element passes at an axial distance from the stop edge into a circumferentially closed jacket sleeve an inner contour (8) of which extends farther radially than the edge contour (4) of the optical component (2).

Abstract: A light source device includes: a plurality of light emitting elements that emit laser light; and a wavelength selective element that includes a light selective region functioning as a resonator mirror of the light emitting element by selecting light of predetermined selective wavelength from the laser light emitted from one of the light emitting elements and reflecting the selected light toward the light emitting element while allowing the remaining laser light to pass therethrough, and a base member having a plurality of the light selective regions so that the wavelengths of the light selected by the light selective regions are different from each other.

Abstract: A coupling lens arranged on an optical path of an optical beam from a VCSEL, which has a refraction plane and a diffraction plane that respectively change a power according to a temperature change and suppresses a beam-waist position change in a main-scanning direction and a sub-scanning directions on the scanning surface caused by the temperature change, by a wavelength change of the optical beam caused by power changes of the refraction plane and the diffraction plane and the temperature change. A deflecting unit deflects the optical beam that passed through the coupling lens. A scanning optical system condenses a deflected optical beam on the scanning surface.

Abstract: An apparatus and method for controlling an optical interferometer are provided. The method includes setting a thermoelectric cooler (TEC) temperature of the optical interferometer to a room temperature, obtaining an optimal temperature using a difference between two output powers of the optical interferometer based on eye opening of the two output powers and applying an optimal heat voltage generating the optimal temperature to a delay adjuster of the optical interferometer, and performing dithering at the optimal temperature to stabilize the optimal heat voltage.

Abstract: An optical signal optical path switching method comprising steps of using a thermal lens based on a distribution of refractive index produced reversibly caused by temperature increase generated in an area of the light-absorbing layer film of thermal lens forming devices 1, 2 and 3, that has absorbed control light beams 121, 122 and 123, and in the periphery thereof, causing the converged signal light beam to exit from the thermal lens forming device with an ordinary divergence angle when the control light beams 121, 122 and 123 have not been irradiated and no thermal lens has been formed, and causing the converged signal light beam to exit from the thermal lens forming device with a divergence angle larger than the ordinary divergence angle when the control light beams have been irradiated and a thermal lens has been formed, and causing the signal light beam to travel straight through holes 61, 62 and 63 of mirrors provided with the holes for the signal light beam to pass through when the control light beams

Abstract: A superconductor-based modulator includes a superconductor coupled to a cold reservoir to receive extreme ultra-violet (EUV) light beams. The light beams are modulated by altering transmission and reflection properties of the superconductor. Magnetic field, temperature, or a combination of both, may be used to control the superconducting properties of the superconductor. The modulator may perform temporal, spatial, and grey-scale modulations. The surface of the superconductor may be patterned with heat or infrared radiation to facilitate light focusing.

Abstract: An optical dispersion compensator including: a spacer element having a top surface and a bottom surface; a thin film, multi-layer mirror formed on the top surface of the spacer element, the thin film mirror having a thermally tunable reflectivity; a highly reflective mirror element formed on the bottom surface of the spacer element; and a heater element for controlling a temperature of the thermally tunable thin film mirror.

Abstract: There are provided laminated bodies or laminated body-containing windows, which comprise isotropic aqueous solutions obtained by dissolving a water-soluble polysaccharide derivative having nonionic amphipathic functional groups in an aqueous medium composed of water and an amphipathic substance, laminated between plates that are at least partially transparent and allow direct vision of the isotropic aqueous solutions, wherein there are added to the isotropic aqueous solutions in appropriate amounts ultraviolet absorbers comprising nonionic or ionic benzophenone derivatives or benzotriazole derivatives which are highly weather resistant and uniformly dissolve in the isotropic aqueous solutions. The isotropic aqueous solutions are transparent and become opaque upon irradiation with light, and exhibit stable reversible change, in order to provide vastly improved weather resistance to the laminated bodies against exposure to sunlight rays over prolonged periods of time.

Abstract: The invention relates to a variable optical attenuator constructed as a Mach Zehnder planar lightwave circuit, particularly including a channel waveguide support structure for heat isolation and stress relief to reduce polarization dependent loss (PDL) and power consumption in the device. Power reduction trenches comprise longitudinal segments having small stress relief pillars of cladding material left in between them in the etching process. The waveguides of the MZI are supported by a main pillar structure and integral stress relief pillars which remain after removal of the trenches. The waveguide is surrounded by air on three sides for improved heat isolation. The performance of the present invention shows substantial improvement in PDL and extinction ratio over the prior art continuous trench design, and also, to a smaller degree, over the case where power reduction trenches are not used at all.

Abstract: Numerous embodiments of an apparatus and method for generating an identification feature are described. In one embodiment of the present invention, portions of an identification character printed with thermochromatic ink are distributed within a three-dimensional matrix of a multi-layer patch. The multi-layer patch may be disposed above a substrate.

Abstract: Numerous embodiments of an apparatus and method for generating an identification feature are described. In one embodiment of the present invention, portions of an identification character printed with thermochromatic ink are distributed within a three-dimensional matrix of a multi-layer patch. The multi-layer patch may be disposed above a substrate.

Abstract: To provide an optical apparatus which controls an interface state to change a focal length by using an optical element having a container sealing first liquid that is conductive or polarized and second liquid that does not mutually mix with the first liquid with their interface in a predetermined form and electrodes provided in the container and of which optical characteristics change according to change of interface form due to application of voltage to the electrodes, and in particular an optical apparatus that controls a duty ratio of alternating current voltage applied to said electrodes for changing said interface form.

Abstract: An optical element holder for holding an optical element includes a holding element to hold the optical element or a holding part provided to the optical element unitedly, wherein there is substantially no heat exchange between the optical element and the holding element or the holding part and the holding element.

Abstract: An optical device (44) includes three optical modulators, three optical modulator holders (447), a plurality of fluid circulating members (440), a cross dichroic prism (444), a fluid branching section (446), a fluid feed-in section (449) and a fluid pressurizing/feeding section (445). The three optical modulator holders (447) are fitted respectively to the three light-incident surfaces of the cross dichroic prism (444) through three supporting members (448). The fluid feed-in section (449) is fitted to the top surface of the cross dichroic prism (444). The fluid branching section (446) and the fluid pressurizing/feeding section (445) are laid one on the other and fitted to the lower surface of the cross dichroic prism (444).

Abstract: One embodiment of an optical modulator includes a substrate, a reflective structure, and at least three thermally actuated supports that movably support said reflective structure on said substrate.

Abstract: The invention relates to a device for holding a beam splitter element having an optically active beam splitter layer in an optical imaging device, the beam splitter element being connected to at least one support element that is fastened in the housing of the imaging device. The connection between the beam splitter element and said at least one support element is designed in such a way that the position of the beam splitter layer of the beam splitter element remains nearly constant relative to the housing independently of temperatures and of thermal stresses acting upon the beam splitter element.

Abstract: A tunable micro-lens and micro-lens array for use in optical communications are disclosed. The micro-lens uses thermo optical material and a temperature controller to adjust the temperature and, hence, the index of refraction of the thermo optical material. In one embodiment, a single temperature controller is used to maintain an array of micro-lenses at a desired temperature. In an alternate embodiment, the individual lenses in an array are separately tunable. The invention may be used with either 2D or 3D lenses, and is well suited for use with existing planar lightwave circuit (PLC) technology.

Abstract: A fiber optic attenuating element is formed of a thermoplastic polymer having (i) a refractive index in the range of between about 1.42 and 1.47 as measured at a temperature of 23° C. and a wavelength of 1550 nm, (ii) a glass transition temperature of at least 105° C., and (iii) an intrinsic loss of less than one dB/mm at 1310 and 1550 nm. In disclosed embodiments, the polymer includes at least one monomer including fluorinated moieties and, optionally, one or more additional monomers. A main body portion of the element has a first planar contact face on a first side and a second planar contact face on a second, opposite side. The contact faces are dimensioned to couple optically with first and second optical fibers when ends of the fibers are urged against the faces by parts of an attenuator device in which the element is mounted.

Abstract: The thermo-optic behavior of an optical path over a range of temperatures is controlled by determining a figure of merit (FoM) for the optical path and including in the path a body of NaBi(Mo1-xWxO4)2 crystalline material that enables the conditions specified by the FOM to be satisfied. The NaBi(Mo1-xWxO4)2 crystalline material is highly transparent at a wavelength of radiation propagating in the path, and has a coefficient of thermal expansion (CTE) and a refractive index n such that the CTE and dn/dT of the etalon compensate one another so as to perform frequency discrimination that is essentially temperature insensitive over the range ?T. The NaBi(Mo1-xWxO4)2 crystalline material exhibits temperature independent transmission characteristics at about room temperature and at a wavelength of about 1550 nm.

Abstract: The present invention is directed to a composite having tunable radiation diffracting properties which includes a flexible, water-free polymeric matrix and a crystalline colloidal array of particles having a lattice spacing, the array being embedded in the polymeric matrix and the lattice spacing changing responsive to stress applied to the polymeric matrix, thereby causing the radiation diffracting properties to change, wherein the polymeric matrix, the lattice spacing and the radiation diffracting properties all return to their original state essentially immediately upon removal of the stress. The present inventive composite is preferably made by a process, which involves forming a preliminary hydrogel polymerized crystalline colloidal array (PCCA), dehydrating the PCCA, and then forming a final, encapsulating polymeric matrix.

Abstract: A thermo-optic lens of the present invention includes a plurality of parallel heating elements having substantially constant center-to-center spacing and respective dimensions varying from the outermost heating elements to the innermost heating elements, and at least two conductive elements for providing a potential across the heating elements. The dimensions of the heating elements are varied such that a parabolic temperature distribution is generated within the thermo-optic lens. A dispersion compensator of the present invention includes a first and a second waveguide grating, each of the waveguide gratings having a first star coupler, an array of waveguides of increasing path lengths, a first end of each of the waveguides of the array of waveguides optically coupled to the first star coupler, and a second star coupler, a second end of each of the waveguides of the array of waveguides optically coupled to the second star coupler.

Abstract: A tunable Bragg grating method and apparatus. In one aspect of the present invention, a method according to an embodiment of the present invention includes directing an optical beam into a first end of an optical path having the first end and a second end disposed in a semiconductor substrate, reflecting a first portion of the optical beam having a first center wavelength back out from the first end of the optical path and tuning the optical path to reflect a second portion of the optical beam having a second center wavelength back out from the first end of the optical path. In one embodiment, the Bragg grating is tuned with a heater used to adjust a temperature of the semiconductor substrate. In another embodiment, charge in charge modulated regions along the optical path is modulated to tune the Bragg grating.

Abstract: A device for variable attenuation of an optical channel includes an elongated core surrounded by a cladding. Optical energy propagating along the longitudinal axis of the core is normally confined thereto by the difference in refractive indices between the core and cladding. The thermo-optic coefficients of the core and cladding are closely matched such that waveguide confinement is substantially invariant with respect to ambient temperature. The device further includes a thermal source arranged above the core. The thermal source is operable to generate a temperature gradient of controllable magnitude along a vertical axis extending through the core. The temperature gradient causes reduction of the local refractive index within the core relative to surrounding regions of the cladding such that a portion of the optical energy is deflected away from the thermal source and extracted from the core.

Abstract: A laser correction element for the correction of angular deviation due to pointing instability and radial displacement due to thermal drift, including one or more of an angular deviation non-symmetric optical element for redirecting a beam axis of a laser beam through a first corrective angle dependent upon the angle of incidence of the laser beam on the angular deviation element to be parallel with an optimum centerline and a radial displacement non-symmetric optical element for redirecting a beam axis of a laser beam through a second corrective angle dependent upon a radial displacement of the beam axis. A collimating non-symmetric optical element may redirect the laser beam through a third corrective angle dependent on radial displacement of the beam axis from a centerline and angle of incidence on the collimating element.

Abstract: An airgap type etalon has a higher degree of design freedom of a wavelength-temperature characteristic so that such a wavelength-temperature characteristic can be freely adjusted. The airgap type etalon includes a fixing block having one flat surface, and a transparent parallel flat plate having parallel flat surfaces formed with an antireflection coating and a reflection augmenting coating thereon, respectively. The flat surface at the antireflection coating side is joined to the flat surface of the fixing block. A parallel flat spacer has a thickness greater than that of the transparent parallel flat plate and an expansion coefficient different from that of the transparent parallel flat plate. One of the flat surfaces of the parallel flat spacer is joined to the flat surface of the fixing block. A transparent flat plate has opposite flat surfaces formed with an antireflection coating and a reflection augmenting coating thereon, respectively.