Abstract: The present invention provides a measurement apparatus that illuminates a surface to be tested having an aspheric surface using light beams that form spherical waves to measure a figure of the surface to be tested, including a detection unit configured to detect interference patterns between light beams from the surface to be tested and light beams from a reference surface, and a controller configured to control processing for obtaining a figure of the surface to be tested based on the interference patterns detected by the detection unit.

Abstract: The present invention provides a measurement apparatus that illuminates a surface to be tested having an aspheric surface using light beams that form spherical waves to measure a figure of the surface to be tested, including a detection unit configured to detect interference patterns between light beams from the surface to be tested and light beams from a reference surface, and a controller configured to control processing for obtaining a figure of the surface to be tested based on the interference patterns detected by the detection unit.

Abstract: An apparatus and associated method for testing a non-symmetric (e.g., phi-polynomial) surface. The apparatus uses several simple (singlet) optical elements (e.g., an Offner null configuration) and a tilted optic under test in combination with an active optical element (e.g., actuated, deformable membrane mirror, optical phase modulator, etc.) that together form a null or quasi-null that allows for conventional null-based interferometry. This solution solves the problem of exceeding the dynamic range of a conventional interferometer when trying to test non-symmetric optical surfaces.

Abstract: An adaptive algorithm is tailored to fit the local fringe frequency of single-frame spatial-carrier data under analysis. Each set of data points used sequentially by the algorithm is first processed with a Fourier Transform to find the local frequency of the fringes being analyzed. That information is then used to adapt the algorithm to the correct phase step thus calculated, thereby optimizing the efficiency and precision with which the algorithm profiles the local surface area. As a result, defects are identified and measured with precision even when the slope of the surface varies locally to the point where the algorithm without adaptive modification would not be effective to measure them. Once so identified, the defects may be measured again locally with greater accuracy by conventional temporal PSI.

Abstract: A device for calibrating a wavefront measuring system (WMS) includes a computer generated hologram (CGH) disposed in an axial path of light traveling to or from the WMS, and an imaging lens disposed in the axial path between the WMS and the CGH. An entrance port of the WMS is configured to form a pupil image of a device under test, where a center of curvature (CoC) of the device under test is located along the axial path between the pupil image and the device under test. The CGH is located along the axial path at the CoC, when the imaging lens is inserted between the CoC and the WMS.

Abstract: A system for measuring deformation of at least one surface of an object including an interferometer for receiving illumination reflected from the surface of the object, and a surface treatment disposed on the surface of the object for providing a retro-reflective patina. The retro-reflective patina is configured to reflect the illumination from the surface of the object. The retro-reflective patina is attached to the surface of the object and may include a plurality of cube corners, or a plurality of dielectric spheres, or a combination of cube corners and dielectric spheres. Impinging light onto the object is provided by an optical source that may be separate from or integral to the interferometer. The impinging light may be directed toward the object through an objective lens, which is also used for receiving the illumination from the object. Alternatively, the impinging light may be directed toward the object by first bypassing the objective lens.

Abstract: The invention relates to an analytical system and method for generating and metering optical signals. The invention includes an optical system having an illuminating system and a sensor platform. The illuminating system includes an arrangement identified as “SLM” for the temporally rapidly variable spatial light modulation, by which in an operating state, illuminating patterns of a freely selectable and rapidly variable geometry, which can be determined by the settings of the SLM, can be generated on the sensor platform from an illuminating light, which enters into this SLM and which includes a substantially homogenous intensity distribution in the in the cross section of the illuminating light at right angles to its direction of expansion.

Abstract: A Fizeau interferometer incorporates an off-axis paraboloidal reflector that forms virtual images of reference and test surfaces and a camera lens that converts the virtual images into real images on a camera detector surface. The camera detector surface is arranged together with the camera lens to accommodate tilting of the virtual images by the off-axis paraboloidal reflector.

Abstract: A beam director subsystem and method for use in a weapons system. The beam director subsystem includes a source of electromagnetic radiation for generating a high energy laser (HEL) beam. The electromagnetic radiation is directed to a secondary mirror that reflects the electromagnetic radiation to a primary mirror for output of the HEL beam. The secondary mirror is generally curved and expands the electromagnetic radiation received from the source prior to outputting the HEL beam from the primary mirror. The subsystem further includes a track telescope coupled to the housing. The track telescope has a track detector configured to receive electromagnetic radiation originating from the HEL and electromagnetic radiation emitted from an illuminator and reflected from an airborne target.

Abstract: A phase imaging method for an optical wavefront acquires a plurality of phase images of the optical wavefront using a phase imager. Each phase image is unique and is shifted with respect to another of the phase images by a known/controlled amount that is less than the size of the phase imager's pixels. The phase images are then combined to generate a single high-spatial resolution phase image of the optical wavefront.

Abstract: The system and the method of the present invention differ from the prior art in that radii of curvature of any length of spherical and cylindrical test surfaces can be optically measured, with only a supplementary dual-focus lens being required in addition to an interferometer or an autocollimator. The supplementary dual-focus lens has a first focal plane, into which the surface vertex of the test surface is positioned, which establishes the cat's eye position (P(cat)), and a second focal plane into which the center of curvature of the test surface is moved, which establishes the autocollimation position (P(aut)) for the test surface. The radius of curvature of the test surface is determined from the distance between the focal planes (D(foc)) and the path of movement which can be reduced to zero.

Abstract: Optical element having an optical surface, which optical surface is adapted to a non-spherical target shape, such that a long wave variation of the actual shape of the optical surface with respect to the target shape is limited to a maximum value of 0.2 nm, wherein the long wave variation includes only oscillations having a spatial wavelength equal to or larger than a minimum spatial wavelength of 10 mm.

Abstract: A method of testing a convex mirror surface figure in which an optical quality substrate material is used having a convex front surface and a rear surface polished to a precise optical figure to create a lens. The lens is then tested by a standard interferometric or wavefront lens-testing method and the convex surface coated once a desired curvature is obtained. Null testing may be attained by passing a collimated interferometer beam through a focusing lens shaped to counter the predicted spherical aberration introduced by a perfect convex mirror/lens. A nominal rear surface figure of the mirror/lens may be used if a precisely figured test window is contacted with the rear surface using a refractive index-matching substance with an index of refraction closely matching the index of refraction of the test optic.

Abstract: An aspheric surface measuring apparatus includes a sample holder mechanism and an interferential optical mechanism, and performs optical interferometric measurement while rotating a sample every time a measurement angle is varied. The sample holder mechanism has a first air spindle for rotating the sample about a test surface axis and a first airslide. The first airslide carries the sample orthogonally or parallel to the test surface axis. The interference optical mechanism has an interference optical system, a first imaging system, and a second imaging system, a second air spindle, and a second airslide. The second spindle revolves or turns the interference optical system and the first and second imaging systems integrally to change a measurement angle between the measurement optical axis and the test surface axis. The second airslide carries the second air spindle orthogonally to the moving direction of the first airslide.

Abstract: Interferometric scanning method(s) and apparatus for measuring test optics having aspherical surfaces including those with large departures from spherical. A reference wavefront is generated from a known origin along a scanning axis. A test optic is aligned on the scanning axis and selectively moved along it relative to the known origin so that the reference wavefront intersects the test optic at the apex of the aspherical surface and at one or more radial positions where the reference wavefront and the aspheric surface intersect at points of common tangency (“zones”) to generate interferograms containing phase information about the differences in optical path length between the center of the test optic and the one or more radial positions. The interferograms are imaged onto a detector to provide an electronic signal carrying the phase information.

Abstract: In a method for improving imaging properties of an illumination system or a projection objective of a microlithographic projection exposure apparatus, which comprises an optical element having a surface, the shape of the surface is measured directly at various points. To this end, a measuring beam is directed on the points, and the reflected or refracted beam is measured, e.g. using an interferometer. Based on deviations of the measured shape from a target shape, corrective measures are derived so that the imaging errors of the optical system are improved. The corrective measures may comprise a change in the position or the shape of the optical element being analyzed, or another optical element of the optical system. The target shape of the surface may, for example, be determined so that the optical element at least partially corrects imaging errors caused by other optical elements.

Abstract: Deformations of a surface of a test object can be measured by attaching mirrors to a surface of a test object, each mirror having a reflective surface with a dimension and a radius of curvature smaller than those of the surface of the test object. Light is directed towards the mirrors and a reference surface, and interference patterns are generated using light reflected from the mirrors and the reference surface. Changes in the surface of the test object are determined based on the interference patterns.

Abstract: The light wave interferometer apparatus is provided and includes: a luminous flux, which is sent from the light source and divided into two portions by the luminous flux separation and composition unit, are combined with each other again under the condition that the divided luminous fluxes hold wavefront information corresponding to the surface shapes of the aspherical lens to be inspected and the reference aspherical lens by the respectively corresponding basis spherical lenses. Therefore, a wavefront difference of the aspherical lens to be inspected with respect to the reference aspherical lens is made to be interference fringe information and formed on an image pickup plane of the interferometer CCD camera. The basis spherical lenses have the basis spherical surfaces, the curvatures of which are equal to each other.

Abstract: A method of measuring the topography of a large, thin, non-flat specular substrate in a production environment with minimal movement of a majority of the measurement apparatus. A gimbal-mounted reflecting element is used to steer a short coherence length probe beam such that the probe beam is substantially perpendicular to a local surface of the substrate. The probe beam and the reference beam are combined and the resulting interference pattern used to characterize defects on the local surface.

Abstract: A method of testing a convex mirror surface figure in which an optical quality substrate material is used having a convex front surface and a rear surface polished to a precise optical figure to create a lens. The lens is then tested by a standard interferometric or wavefront lens-testing method and the convex surface coated once a desired curvature is obtained. Null testing may be attained by passing a collimated interferometer beam through a focusing lens shaped to counter the predicted spherical aberration introduced by a perfect convex mirror/lens. A nominal rear surface figure of the mirror/lens may be used if a precisely figured test window is contacted with the rear surface using a refractive index-matching substance with an index of refraction closely matching the index of refraction of the test optic.

Abstract: A method of testing a convex mirror surface figure in which an optical quality substrate material is used having a convex front surface and a rear surface polished to a precise optical figure to create a lens. The lens is then tested by a standard interferometric or wavefront lens-testing method and the convex surface coated once a desired curvature is obtained. Null testing may be attained by passing a collimated interferometer beam through a focusing lens shaped to counter the predicted spherical aberration introduced by a perfect convex mirror/lens.

Abstract: The present invention provides a measurement apparatus that illuminates a surface to be tested having an aspheric surface using light beams that form spherical waves to measure a figure of the surface to be tested, including a detection unit configured to detect interference patterns between light beams from the surface to be tested and light beams from a reference surface, and a controller configured to control processing for obtaining a figure of the surface to be tested based on the interference patterns detected by the detection unit.

Abstract: In a method for improving imaging properties of an illumination system or a projection objective of a microlithographic projection exposure apparatus, which comprises an optical element having a surface, the shape of the surface is measured directly at various points. To this end, a measuring beam is directed on the points, and the reflected or refracted beam is measured, e.g. using an interferometer. Based on deviations of the measured shape from a target shape, corrective measures are derived so that the imaging errors of the optical system are improved. The corrective measures may comprise a change in the position or the shape of the optical element being analyzed, or another optical element of the optical system. The target shape of the surface may, for example, be determined so that the optical element at least partially corrects imaging errors caused by other optical elements.

Abstract: An apparatus and method for reducing speckle of a laser beam is disclosed. The apparatus includes a light guide, a highly reflective mirror at the input face of the light guide and a partially-transmissive display after the exit face of the light guide. A coherent laser beam is introduced into the light guide through a clear aperture in the highly reflective mirror. Within the light guide, the laser beam gets separated into plural, successive beamlets having different phase shifts, different polarization states and/or path length differences equal to or greater than the coherence length of the laser beam. The beamlets exit through the partially-transmissive display to provide output laser light with reduced speckle. The light guide can be either a solid light pipe of transmissive material or a hollow tunnel with reflective interior sidewalls.

Abstract: Interferometric scanning method(s) and apparatus for measuring test optics having aspherical surfaces including those with large departures from spherical. A reference wavefront is generated from a known origin along a scanning axis. A test optic is aligned on the scanning axis and selectively moved along it relative to the known origin so that the reference wavefront intersects the test optic at the apex of the aspherical surface and at one or more radial positions where the reference wavefront and the aspheric surface intersect at points of common tangency (“zones”) to generate interferograms containing phase information about the differences in optical path length between the center of the test optic and the one or more radial positions. The interferograms are imaged onto a detector to provide an electronic signal carrying the phase information.

Abstract: The invention relates to a method and to an apparatus for interferometrically determining a deviation of an actual shape of an effective reflection surface (12) of a test object (14) from a desired shape of the effective reflection surface (12). In the method according to the invention electromagnetic illumination radiation (24) is produced by means of an illumination device (16) and provided as an input wave (30). The input wave (30) passes through a diffractive optical element (18) and leaves the latter as an incoming measuring wave (42), the wave front of the input wave (30) being transformed upon passing through the optical element (18) such that the wave front of the incoming measuring wave (42) is adapted to the desired shape of the effective reflection surface (12).

Abstract: An apparatus for performing surface measurement of an inspection-object surface and profile irregularity measurement and surface defect observation of an inspection-object lens using a Fizeau interferometric optical system.

Abstract: A method of measuring the topography of a large, thin, non-flat specular substrate in a production environment with minimal movement of a majority of the measurement apparatus. A gimbal-mounted reflecting element is used to steer a short coherence length probe beam such that the probe beam is substantially perpendicular to a local surface of the substrate. The probe beam and the reference beam are combined and the resulting interference pattern used to characterize defects on the local surface.

Abstract: A variable transmittance optical element is provided in an imaging optical system of an endoscope, and includes small etalons or multiple microscopic mirror that have an effective part that allows passage of a light beam received at a unit light receiving area that corresponds to an individual pixel, or a plurality of pixels, of an image pickup device that is provided in the imaging optical system of the endoscope. Each of said small etalons or microscopic mirrors have facing surfaces that are arranged so as to be parallel to one another on a transparent substrate; and the transparent substrate and an image pickup surface of the image pickup device are positioned so that each of the small etalons or microscopic mirrors allows passage of the light beam.

Abstract: Crosstalk between a drive coil and a primary feedback coil is eliminated by positioning a secondary feedback coil in proximity with the drive coil for contamination by the crosstalk to the same extent as the primary feedback coil, and by processing feedback signals generated by the feedback coils to cancel the crosstalk. The drive coil is used to oscillate a scan mirror employed in an image projection arrangement or an electro-optical reader.

Abstract: In a method for improving imaging properties of an illumination system or a projection objective of a microlithographic projection exposure apparatus, which comprises an optical element having a surface, the shape of the surface is measured directly at various points. To this end, a measuring beam is directed on the points, and the reflected or refracted beam is measured, e.g. using an interferometer. Based on deviations of the measured shape from a target shape, corrective measures are derived so that the imaging errors of the optical system are improved. The corrective measures may comprise a change in the position or the shape of the optical element being analyzed, or another optical element of the optical system. The target shape of the surface may, for example, be determined so that the optical element at least partially corrects imaging errors caused by other optical elements.

Abstract: In a method for improving imaging properties of an illumination system or a projection objective of a microlithographic projection exposure apparatus, which comprises an optical element having a surface, the shape of the surface is measured directly at various points. To this end, a measuring beam is directed on the points, and the reflected or refracted beam is measured, e.g. using an interferometer. Based on deviations of the measured shape from a target shape, corrective measures are derived so that the imaging errors of the optical system are improved. The corrective measures may comprise a change in the position or the shape of the optical element being analyzed, or another optical element of the optical system. The target shape of the surface may, for example, be determined so that the optical element at least partially corrects imaging errors caused by other optical elements.

Abstract: The present invention relates to vibration-insensitive point-diffraction interferometry. For the purpose of obtaining high immunity to vibration, a single-mode optical fiber is used to generate the reference wave, by means of point diffraction, directly from a measurement wave reflected from test objects. The capability of vibration desensitization is further strengthened by adding a spatial phase-shift device that enables four interferograms of different amounts of phase shift to be obtained simultaneously with no time delay between interferograms. The present invention may be effectively used in the design of measuring systems for in-line applications where measurements need to be performed in the presence of significant levels of vibration.

Abstract: A method for determining at least one of distortion and de-focus for an optical imaging system. The method includes determining wavefront aberrations in a pupil plane of the optical imaging system by a wavefront measurement method, determining focus offset measured values in an xy-direction and/or z-direction for one or more different illumination settings by a test pattern measurement method with imaging and comparative evaluation of test patterns for the optical imaging system, and determining values for one or more aberration parameters that relate to the distortion and/or image surface from a prescribed relationship between the determined wavefront aberrations and the determined focus offset measured values.

Abstract: An interferometer is provided, comprising a source, a unit under test (UUT) with at least a first surface and second surface, a reflective optic, a detector and light from the source. The light is transmitted through the unit under test and reflects off of the reflective optic, which directs the light back to the unit under test. A first portion of light is reflected off the first surface of the UUT. A second portion of light is reflected off the second surface of the UUT. The first and second portions of light are then reflected by the reflective optic and are then transmitted through the UUT. The two portions of light are incident on the detector, where the first and second portions of light coherently add and the interference pattern is detected by the detector. A method for measuring the transmitted wavefront of the UUT is also provided.

Abstract: A laser interferometer is disclosed comprising a housing capable of being substantially repeatably mounted to a wall of an environmental chamber, the housing including a laser source, a reflector attached to an object located within the environmental chamber, and a light passage provided through the wall of the environmental chamber enabling passage of a laser beam from the laser source to the reflector. At least one beam steerer may be provided for adjusting direction of passage of a laser beam through the light passage. Also disclosed is a column laser interferometer.

Abstract: The focus of the collimating lens in the optical train of a Fizeau interferometer is adjusted to change the power of the test beam illuminating the transmission sphere. As a result, the rays can be made sufficiently perpendicular to the reference surface to eliminate the chromatic focus shift and non-common path errors produced by a light source of wavelength different from the design wavelength of the transmission sphere. By making the position of the collimating lens relative to the beam expander adjustable along the optical axis over some small range, illumination sources of various wavelength can be used in the same interferometer.

Abstract: Interferometric scanning method(s) and apparatus for measuring optics either having aspherical surfaces or that produce aspherical wavefronts. A test optic is aligned and moved with respect to a scanning axis relative to the origin of a known spherical wavefront that is generated with a reference surface to intersect the test optic at the apex of the aspherical surface and at radial zones where the spherical wavefront and the aspheric surface possess common tangents. The test surface is imaged onto a space resolving detector to form interferograms containing phase information about the differences in optical path length between the reference surface and the test surface while the axial distance which the test optic moves relative to the spherical reference surface is interferometrically measured. The deviation in the shape of the aspheric surface from its design in a direction normal to the aspheric surface is determined and reported.

Abstract: In a method for calibrating a radius test bench for measuring radii of optical elements, in particular of lenses and spherical mirrors, there are provided an illuminating system 1 that generates a spherical wave and a diffractive optical element 3 that retroreflects a spherical wave of a specific radius into itself. The diffractive optical element 3 is introduced into the radius test bench in at least two positions, a first position thereof being a cat's eye position 1 and another position being an autocollimation position, as a result of which it is possible to use the radius of curvature simulated by the diffractive optical element 3 to detect deviations of the radius test bench from this radius of curvature as errors of the radius test bench, and thus to take them into account in the measurements of optical elements to be tested.

Abstract: A method of processing an optical element comprises providing an interferometer optics; arranging a calibrating substrate in a beam of measuring light emitted by the interferometer optics; superimposing measuring light having traversed the first and second surfaces of the calibrating substrate with reference light, and taking a first interferometric measurement of the superimposed measuring light and reference light; arranging the aspherical surface of the optical element in the beam of measuring light emitted by the interferometer optics, while the calibrating substrate is not arranged in the beam of measuring light; superimposing measuring light having interacted with the aspherical surface and the reference light, and taking a second interferometric measurement of the superimposed measuring light and reference light; determining deviations of the aspherical surface from a target shape thereof in dependence of the first and second measurements; and machining the aspherical surface of the optical element.

Abstract: There is provided an interferometer for measuring a surface shape of an optical element using interference, including a reference wave-front generating unit for generating a reference wave front for measuring the surface shape, which is provided in a target optical path, and includes an Alvarez lens.

Abstract: An aspheric surface measuring apparatus includes an interferometer which generates incident light; a test piece having an aspheric surface from which the incident light is reflected as test light; a first optical element disposed on an optical path of the incident light, having at least one surface with a hologram for diffracting the incident light toward the test piece; and a second optical element disposed after the first optical element, which transmits the incident light toward the aspheric surface and has a concave surface to reduce an incident angle of the test light entering the hologram after having been reflected from the aspheric surface. Alternatively, a single optical element with a hologram and a concave surface can be used instead of the separate first and second optical elements. An extremely aspheric lens can be precisely measured using the apparatus.

Abstract: A method of manufacturing an optical element having an optical surface of a target shape includes performing an interferometric test using an interferometer optics, wherein the interferometer optics includes a hologram that deflects a beam of measuring light by a substantial angle or that displaces an axis of symmetry of measuring light emerging from the hologram with respect to an axis of symmetry of measuring light incident on the hologram.

Abstract: A frequency-scanning interferometer is modified to include a diffuse reference surface. An illuminating system produces an expanding measuring beam, portions of which reflect from a test object surface and the diffuse reference surface on converging paths to an imaging system. Interference patterns between overlapping images of the object and reference surfaces are generated at a plurality of frequencies for measuring the object surface with respect to the reference surface.

Abstract: A system for characterizing an aspheric surface with respect to an expected shape thereof, comprising a light source to emit light of desirable properties. A ferrofluid deformable mirror apparatus has a reflective surface being controllably deformable. The reflective surface is shaped as a function of the expected shape so as to reflect light in a known path toward a detector. Optical elements project light from the light source onto the aspheric surface such that light is reflected along an expected path if the aspheric surface has the expected shape. Light is reflected from the aspheric surface along an actual path. The optical elements project light on the reflective surface of the ferrofluid deformable apparatus such that light is reflected along the known path. A detector receives light reflected along at least one of the actual path and the known path to obtain an interference pattern as a function of the expected path.

Abstract: Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics having spherical, mildly aspherical and multiple, mildly aspherical surfaces. At least a partial spherical wavefront is generated from a known origin along a scanning axis through the use of a spherical reference surface positioned along the scanning axis upstream of the known origin. A test optic is aligned with respect to the scanning axis and selectively moved along said scanning axis relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at one or more radial positions where the spherical wavefront and the aspheric surface intersect at points of common tangency to generate interferograms containing phase information about the differences in optical path length between the center of the test optic and the one or more radial positions.

Abstract: Disclosed is an interferometer that enables high-speed and high-precision measurement of a surface shape of an article and a method of producing such interferometer. Also disclosed is a method of measuring a surface shape of an article by use of such interferometer. The interferometer includes an optical system having an optical element being effective to make, into an aspherical wave, a wavefront of light to be projected on the article to be inspected, and also being arranged to be replaceable by another optical element.

Abstract: Interferometric apparatus and methodology for precisely measuring the shape of rotationally and non-rotationally symmetric optical surfaces comprising an illumination source with two wavelengths, a transmission flat with a reference surface, a basic optical system for producing a wavefront of predetermined shape, a compensation component having an aspheric wavefront shaping surface and an aspheric reference surface. The aspheric shaping surface modifies the predetermined wavefront so that it impinges on the aspheric reference surface with a shape substantially that same as that of aspheric reference surface. For a given aspheric reference surface, the radius or curvature and spacing of the aspheric shaping surface are optimized so that its aspheric departure is no larger than that of the aspheric reference surface. Precise alignment in six degrees of freedom is provided via feedback control.

Abstract: To measure a convex mirror, a reference beam and a measurement beam are both provided through a single optical fiber. A positive auxiliary lens is placed in the system to give a converging wavefront onto the convex mirror under test. A measurement is taken that includes the aberrations of the convex mirror as well as the errors due to two transmissions through the positive auxiliary lens. A second measurement provides the information to eliminate this error. A negative lens can also be measured in a similar way. Again, there are two measurement set-ups. A reference beam is provided from a first optical fiber and a measurement beam is provided from a second optical fiber. A positive auxiliary lens is placed in the system to provide a converging wavefront from the reference beam onto the negative lens under test. The measurement beam is combined with the reference wavefront and is analyzed by standard methods.

Abstract: A method and system for measuring optical characteristics of a sub-component within a composite optical system is disclosed. In one embodiment, the present invention generates an optical response from a composite optical system. The present embodiment then separates an optical response of a sub-component from the optical response of the composite optical system. The present embodiment then determines the optical characteristics of the sub-component by utilizing at least one portion of the optical response of the sub-component.