Off-axis optical fiber sensor

Abstract

This application discloses embodiments of optical assemblies used in optical sensor systems where access to components or areas of equipment to be detected is difficult. In one embodiment, the optical assembly may include a housing having an optical waveguide that operates to guide an optical signal to an optical element configured to change the direction of propagation of the optical signal to a direction perpendicular to the original propagation direction. The optical element may have a refractive surface and a reflective surface. By using two such optical assemblies arranged optically in series, a user can route an optical signal to propagate along an optical axis that is parallel to the original propagation axis but offset laterally from the original propagation axis. Such optical assemblies can enable optical access to areas of semiconductor manufacturing equipment such as process chambers, wafer supports, electrostatic chucks, showerheads, edge rings, or end effectors of wafer handling robots.

Description

Technical Field

[0001] Cross-reference of related applications This application claims the priority of U.S. Provisional Patent Application No. 63 / 452,184, filed on March 15, 2023, entitled "Off-Axis Fiber Optic Sensor", the content of which is incorporated herein by reference in its entirety.

Background Art

[0002] background Optical sensors, particularly fiber optic sensors, are used in various applications in semiconductor manufacturing, including the measurement of temperature, strain, and position of wafers, electrostatic chucks, showerheads, and other components in a radio frequency environment with strong stimulating chemicals inside a wafer processing chamber. Such sensors must have a small form factor to access difficult-to-reach areas of the chamber and its components. Conventional fiber optic sensors have been found useful so far, but some drawbacks have been identified. For example, when the sensing element is offset from the optical fiber that provides the light used to interact with the object being measured, the fiber must be bent at an acute angle. To do this, in many cases, the fiber must be placed inside a metal capillary so that the bending stress does not damage the fiber. In view of the above, there is a continuing need for fiber optic sensors that can access narrow spaces without the risk of damaging the fiber.

Summary of the Invention

[0003] overview The following detailed description relates to various embodiments of a compact optical assembly configured to change the propagation direction of radiation in such an optical sensor.

[0004] In one embodiment, the optical assembly comprises a housing and an optical element, at least partially disposed within the housing and having a curved surface and a reflective surface, wherein the optical element is configured to direct first light radiation incident on a first portion of the curved surface to exit a second portion of the curved surface after being at least partially reflected from at least a portion of the reflective surface. The light radiation incident on the first portion of the curved surface has a first propagation direction along a first optical axis, and the light radiation exiting the second portion of the curved surface has a second propagation direction along a second optical axis, the second propagation direction being different from the first propagation direction. The optical element may be provided as a single optical element or as a plurality of optical elements. The optical element may be provided as a half-ball lens, a hyper-hemispherical lens, a hypo-hemispherical lens, a semi-elliptical lens, or a hemispherical lens. In various embodiments, the optical element can be made from silica, quartz glass, soda-lime glass, borosilicate glass, sapphire, aluminum nitride, silicone, colored glass, IR / UV optical materials (silicon, zinc sulfide, germanium, arsenic triphosphate, barium fluoride, calcium fluoride, magnesium fluoride, zinc selenide), or plastic.

[0005] The optical assembly may further include a light source configured to emit a first light emission or outgoing signal having a first spectral power distribution, and a detector configured to measure a second light emission or return signal having a second spectral power distribution, wherein the first light emission or outgoing signal is incident on a first portion of the curved surface, and the second light emission or return signal is exiting the first portion of the curved surface. The first spectral power distribution may be the same as or different from the second spectral power distribution. The optical assembly may further include a reflective surface configured to reflect at least a portion of the light emission exiting the second portion of the curved surface and to direct the at least portion back to the second portion of the curved surface.

[0006] The optical assembly may be at least one component of a temperature sensor, a presence sensor, or a distance sensor. The optical assembly may further include a sensing element configured to emit a second light emission or return signal, the sensing element including a phosphor, and the optical assembly is at least one component of a temperature sensor.

[0007] In some embodiments, the optical assembly may further comprise a first optical waveguide having a first end and a second end, the second end being at least partially located within a housing, and the first optical waveguide being configured to allow first light radiation to propagate from the first end to the second end and second light radiation to propagate from the second end to the first end, with the second end of the first optical waveguide communicating optically with a first portion of a curved surface. The first optical waveguide may comprise at least one fiber bundle and at least one of an optical rod, a hollow optical rod, a double-clad fiber, a light pipe, a glass rod, or a sapphire rod. At least one of the optical rod, a hollow optical rod, a double-clad fiber, a light pipe, a glass rod, or a sapphire rod may be located between the fiber bundle and the optical element. The optical assembly may further comprise a second optical waveguide which may have the same configuration as the first optical waveguide. The optical assembly may further include a rotational joint configured to allow the first optical waveguide to rotate in a plane perpendicular to the first propagation direction.

[0008] In another embodiment, the optical assembly comprises a housing and a first optical waveguide defining a first optical axis, the first optical waveguide including a first end and a second end, the second end being at least partially located within the housing. The first optical waveguide may be configured to allow first light radiation to propagate from the first end to the second end and second light radiation to propagate from the second end to the first end. The optical assembly may further comprise a first optical port through which the first light radiation can pass and propagate, and a second optical port through which the second light radiation can pass and propagate. The optical assembly may further comprise an optical element having a curved surface and a reflective surface, wherein (i) a second end of a first optical waveguide communicates optically with a first portion of the curved surface of the optical element, (ii) a first optical port communicates optically with a first portion of the curved surface of the optical element, (iii) a second optical port communicates optically with a second portion of the curved surface of the optical element, (iv) at least one portion of the first portion of the curved surface differs from at least one portion of the second portion of the curved surface, and (v) the optical element is configured to (a) direct first light radiation from the first optical waveguide to the second optical port, and (b) direct second light radiation from the second optical port to the first optical waveguide.

[0009] In another embodiment, the optical assembly comprises a housing, a first optical element coupled to the housing and having a first curved surface and a first reflective surface, and a second optical element coupled to the housing and communicating optically with the first optical element and having a second curved surface and a second reflective surface. The optical assembly may further comprise at least one optical waveguide communicating optically with the first optical element and the second optical element, the optical waveguide having a first end, a second end and a second optical axis, the first optical element being configured to receive a first optical radiation propagating along the first optical axis and to direct the first optical radiation to the optical waveguide as a second optical radiation propagating along the second optical axis, and the second optical element being configured to receive a second optical radiation from the optical waveguide and to direct the second optical radiation to propagate along the third optical axis. A second optical element may be configured to receive a fourth light emission propagating along a third optical axis and direct the fourth light emission to an optical waveguide as a fifth light emission propagating along a second optical axis, and at least one first optical element may be configured to receive a fifth light emission from at least one optical waveguide and direct the fifth light emission to a sixth light emission propagating along a first optical axis. In various embodiments, the third light emission includes excitation radiation propagating along a third optical axis to a sensing element, and the fourth light emission includes fluorescence emission propagating in opposition along the third optical axis. The first, second, and third light emissions include excitation radiation propagating to a sensing element, and the fourth, fifth, and sixth light emissions include fluorescence emission propagating in opposition to a detector. The optical assembly may further include a light emission source configured to emit excitation radiation propagating along a first optical axis. [Brief explanation of the drawing]

[0010] Brief explanation of the drawing Various embodiments of the improved optical assembly and optical fiber sensor are described in more detail through the accompanying drawings.

[0011] [Figure 1]FIG. 1 is a schematic cross-sectional view of an embodiment of an optical assembly configured to change the axis of propagation of light radiation in an optical sensor system.

[0012] [Figure 2] FIG. 2 is a schematic cross-sectional view of an embodiment of an optical assembly.

[0013] [Figure 3] FIG. 3 is a schematic cross-sectional view of an embodiment of an optical assembly.

[0014] [Figure 4] FIG. 4 is a schematic cross-sectional view of an embodiment of an optical assembly.

[0015] [Figure 5] FIG. 5 is a schematic cross-sectional view of an embodiment of an optical assembly.

[0016] [Figure 6] FIG. 6 is a schematic cross-sectional view of an embodiment of an optical assembly.

[0017] [Figure 7] FIG. 7 is a schematic cross-sectional view of an embodiment of an optical assembly.

[0018] [Figure 8] FIG. 8 is a schematic cross-sectional view of an embodiment of an optical sensor system configured to measure at least one property of an object.

[0019] [Figure 9] FIG. 9 is a schematic cross-sectional view of an embodiment of an optical assembly.

[0020] [Figure 10] FIG. 10 is a schematic cross-sectional view of an alternative embodiment of the optical assembly shown in FIG. 9.

[0021] [Figure 11]Figure 11 is a schematic cross-sectional view of an alternative embodiment of the optical assembly shown in Figure 9.

[0022] [Figure 12] Figure 12 is a schematic cross-sectional view of an alternative embodiment of the optical assembly shown in Figure 9.

[0023] [Figure 13] Figure 13 is a schematic cross-sectional view of one embodiment of an optical assembly.

[0024] [Figure 14] Figure 14 is a schematic cross-sectional view of one embodiment of an optical assembly.

[0025] [Figure 15] Figure 15 is a schematic optical diagram of one embodiment of the optical arrangement.

[0026] [Figure 16] Figure 16 is a schematic optical diagram of one embodiment of the optical arrangement.

[0027] [Figure 17] Figure 17 is a schematic optical diagram of one embodiment of the optical arrangement.

[0028] [Figure 18] Figure 18 is a schematic optical diagram of one embodiment of the optical arrangement. [Modes for carrying out the invention]

[0029] Detailed explanation Exemplary embodiments are described in this section with reference to the attached drawings. Unless otherwise explicitly stated, the sizes, positions, and distances between components, features, and elements in the drawings are not necessarily to an accurate scale and may be exaggerated for clarity. In the drawings, similar numbers refer to similar elements throughout. Therefore, the same or similar numbers may be mentioned in other drawings even if they are not mentioned or described in the corresponding drawings. Also, elements not indicated by reference numbers may be mentioned in other drawings.

[0030] The terminology used herein is intended solely to describe and not limit to specific exemplary embodiments. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art. The singular forms “a,” “an,” and “the” used herein are intended to include the plural form unless the context clearly indicates otherwise. The terms “at least one,” “at least,” and “one or more” are intended to include both the singular and plural forms, depending on the context. When used herein, the terms “equipment” and / or “contain” specify the existence of an expressed feature, complete, step, action, element, and / or component, but it should be recognized that this does not exclude the existence or addition of one or more other feature, complete, step, action, element, component, and / or group thereof. Unless otherwise specified, terms such as “first,” “second,” etc., are used solely to distinguish one element from another. For example, one coupler might be called the "first coupler," and similarly, another coupler might be called the "second coupler," and vice versa.

[0031] Unless otherwise specified, spatially relative terms such as “below,” “beneath,” “lower,” “above,” and “upper” and “opposing” may be used herein to facilitate descriptions of the relationship between one element or feature and another, as shown in the figures. It should be recognized that these spatially relative terms are intended to encompass orientations other than those depicted in the figures. For example, if an object in the figure is inverted, an element described as “below” or “below” another element or feature would face “above” that other element or feature. Thus, the exemplary term “below” can encompass both upward and downward orientations. An object may also be in other orientations (e.g., rotated 90 degrees or other orientations), and the spatially relative descriptors used herein may be interpreted accordingly. A set of reference axes (e.g., X, Y, Z), reference directions, or reference coordinates, and rotations around them (e.g., θX, θY, θZ) may be included in the figures for the purpose of adapting the reader to facilitate understanding of the figures and this specification, and does not necessarily indicate that any particular feature or element is aligned with or orthogonal to any other feature or element.

[0032] The paragraph numbers used herein are for organizational purposes only and should not be construed as limiting the subject matter unless expressly stated otherwise. Many different forms, embodiments, and combinations are possible without departing from the spirit and teachings of this disclosure, and it should be understood that this disclosure should not be construed as being limited to the exemplary embodiments described herein. On the contrary, these examples and embodiments are provided to convey the scope of this disclosure to those skilled in the art, making it sufficient and complete.

[0033] Embodiments of the present invention provide novel methods for low-profile optical sensors and optical probes. These methods address several shortcomings and challenges present in the current design and manufacture of such sensor probes. Advantageously, a single optical element can be utilized to allow reorientation of the optical axis in a small footprint, thereby providing improved performance in challenging environments (e.g., high optical power, high operating temperature, corrosive chemical environments) while simplifying the manufacturing process (e.g., by eliminating tight optical alignment tolerances). For example, by using a simple optical element, the inner surface of the housing can be used as an optical alignment reference plane. In some embodiments, the optical assembly may be hermetically sealed, have components with low gas emission products, and be vacuum-compatible. In some embodiments, the optical design utilizes inexpensive optical components (e.g., hemispherical lenses) with high numerical apertures configured to reduce optical fluence and extend the lifespan of the optical components. A single optical surface can be used so that an anti-reflective coating only needs to be applied to a single surface, and the surface of the optical component can be used as a protective window to seal the components of the optical assembly from the surrounding environment. The optical materials may be selected to allow for the use of internal reflection, thereby potentially eliminating the need for reflective coatings on some optical surfaces. The embodiments described herein also allow all components of the optical assembly to be nonmetallic so as not to affect or interfere with the electric field of the high RF power environment inside the semiconductor process chamber.

[0034] Figure 1 shows a cross-sectional view of a pair of optical assemblies 100 configured to change the direction of propagation of light radiation, used in conjunction with an optical fiber sensor system or other optical sensor system. In various embodiments, the optical fiber sensor system can be used to detect various characteristics or parameters, for example, to measure the temperature of the surface 32 of an object 30 (e.g., a semiconductor wafer, an electrostatic chuck, or other structure), or to detect the presence or absence of an object 30 when there is little room to insert an optical probe. For example, as shown in Figure 1, in a particular wafer manufacturing process, the temperature of the wafer surface 32 at a particular location 34 must be controlled, but access to that area of ​​the wafer is restricted by the design of the wafer support 20. In various embodiments, the wafer support 20 may be a chuck or an electrostatic chuck. In various embodiments, the pair of optical assemblies 100 may be installed in other parts or components within the wafer manufacturing equipment chamber, such as an edge ring, showerhead, etc. For example, access to the chuck 20 may be limited to a first port 24 formed in the chuck 20, which is laterally offset from a second port 26 formed in the chuck 20, making it difficult to position a temperature probe. To solve this problem, an optical assembly is needed that can direct light emission from a first optical axis A1 to a third optical axis A3 to provide light access to location 34, where the third optical axis A3 is parallel to the first optical axis A1 but offset from it. Such an optical assembly may be positioned within a cavity 22 formed in the chuck 20. In some embodiments, the light emission 50 (also referred to herein as “excitation emission 50”) includes wavelengths that operate to excite a sensing element (e.g., a phosphor) that is in thermal communication with the surface 32. Excitation radiation 50 (for example, from a light source such as an LED or laser) propagates along the first optical axis A1 through the first port 24 into the first optical assembly 100, where the excitation radiation 50 is directed as excitation radiation 56 propagating along the second optical axis A2 and enters the second optical assembly 100.In the second optical assembly 100, the excitation radiation 56 is directed as excitation radiation 60 along the third optical axis A3 to a sensing element (not shown in Figure 1 for clarity). When the sensing element is provided as a phosphor, the excitation radiation 60 causes the phosphor to fluoresce, and at least a portion of this fluorescence radiation is directed in the opposite direction along the third optical axis A3 as counterpropagated fluorescence radiation 62, enters the second optical assembly 100, and is directed as counterpropagated fluorescence radiation 58 that propagates along the second optical axis A2 to the first optical assembly 100. In the first optical assembly 100, the counterpropagated fluorescence radiation 58 is directed in the opposite direction along the first optical axis A1 as counterpropagated fluorescence radiation 52, and propagates through the first port 24 to other parts of the photosensor configured to measure the properties of the counterpropagated fluorescence radiation 52 to measure the temperature or other properties of the surface 32 at location 34.

[0035] Figure 2 shows a cross-sectional view of an exemplary embodiment of an optical assembly 100 used in an optical sensor or optical sensor system. The optical assembly 100 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or a wide variety of sensors or sensor systems. In the illustrated embodiment, the optical assembly 100 has a first optical port 170 and a second optical port 172, the first optical port 170 is configured to allow light radiation to propagate bidirectionally through the first optical port 170, and the second optical port 172 is configured to allow light radiation to propagate bidirectionally through the second optical port 172. For example, light radiation 140 can propagate through the optical port 170 toward the optical element 120, and light radiation 142 (also referred to herein as "counterpropagated radiation 142") can propagate from the optical element 120 toward the first optical port 170. The double-ended block arrows indicate light radiation 140 propagating in the first direction and counterpropagated radiation 142 propagating in the opposite direction. This rule is used throughout this disclosure to indicate pairs of radiated and counterpropagated radiation, such as 150 / 152, 160 / 162, 180 / 182, 250 / 252, etc., throughout this detailed description. Generally, radiated radiation 140 and counterpropagated radiation 142 are described as propagating along the optical axis A1, but those skilled in the art will understand that radiated radiation 140 and counterpropagated radiation 142 may also propagate parallel to the optical axis A1 but offset from it. This also applies to radiated and counterpropagated radiation propagating along the optical axes A2 and A3. Furthermore, those skilled in the art will understand that optical radiation may not propagate precisely parallel to the optical axis but can propagate through various waveguides or optical fibers by total internal reflection.

[0036] In the embodiment shown in Figure 2, the optical assembly 100 is configured to change the direction of light emission propagation by an angle of approximately 90 degrees, but in other embodiments described in more detail below, the optical assembly 100 may be configured to change the direction of light emission propagation by an angle smaller than 90 degrees or an angle larger than 90 degrees.

[0037] The optical assembly 100 includes at least one housing 110, the housing 110 having a first opening or passage 114 and a second opening or passage 118. An optical element housing passage or relief 119 is formed in the housing 110, configured to receive at least one optical element 120, the optical element 120 being at least partially positioned within the relief 119. In various embodiments, the optical element housing passage or relief 119 is configured as a surface that passively optically aligns the optical element 120 with respect to other features or optical elements used in the optical assembly 100. In the illustrated embodiment, the passage 118 is a circular opening formed adjacent to the optical element 120. An internal relief 129 may also be formed in the housing 110. The housing 110 can be formed from any of a wide variety of materials, including, but not limited to, metals (aluminum, copper or copper-based alloys (brass, bronze)), stainless steel, nickel-based alloys (Kovar, Invar, Inconel), tungsten carbide, copper-tungsten, optical materials (glass, ZeroDur), ceramics, plastics, and composite materials (phenol fiber, glass fiber, carbon fiber). Those skilled in the art will understand that the housing 110 can be formed from any variety of materials or combinations of materials. Figure 2 shows the housing Although the housing 100 is shown as having a rectangular prism shape, those skilled in the art will understand that the housing 100 may have a different shape. In the illustrated embodiment, the housing 100 is a single-piece housing, but in other embodiments, the housing 100 may consist of two or more parts. Thanks to the compact design of the optical assembly 100, in one embodiment, the dimensions of the housing 110 perpendicular to the first propagation direction can be about 6 mm or less. In other embodiments, the dimensions of the housing 110 perpendicular to the first propagation direction can be 3 mm or less.

[0038] An optical element 120 is positioned within a housing 110, having a first surface 122 with surface portions 123 and 124, and a second surface 126 with surface portion 128. In the illustrated embodiment, the first surface 122 is curved (also referred to herein as a “curved surface”). Accordingly, surface portions 123 and 124 are also curved. Surface portions 123 and 124 are configured so that light radiation can pass through their surface portions. The second surface 126 is configured to reflect light radiation that enters surface portion 123 toward surface portion 124, and in the opposite direction toward surface portion 124. In the illustrated embodiment, the second surface 126 is oriented at an angle of approximately 45 degrees with respect to the propagation direction of light radiation entering and leaving the optical assembly 100. In one embodiment, the optical element 120 has a focal length suitable for focusing a beam at a specified distance from surface 122. In one embodiment, the focal length of the optical element 120 is between 1 millimeter and 350 millimeters. In the illustrated embodiment, although not shown, the second surface 126 is positioned at a distance from the structure of the housing 110, leaving an air gap between the housing 110 and the second surface 126. When configured in this way, the second surface 126 is configured to reflect light radiation internally (for example, by the difference in refractive index between the optical element 120 and the air in the gap between the housing 110 and the second surface 126). When configured in this way, the second surface 126 may also be referred to herein as the “internal reflective surface 126”. In other embodiments, the second surface 126 may be coated with a reflective material or reflective layer (not shown) having a reflectivity selected to reflect a certain percentage of the incident light radiation. In various embodiments, the reflective layer may be provided as a dichroic mirror, a total reflection mirror, at least one metal film, or at least one dielectric film or dielectric coating. The percentage of light radiation reflected may range from 1% to 100%. In yet another embodiment, at least a portion of the second surface 126 may include a dichroic mirror.In various embodiments, such a dichroic mirror may be configured to substantially transmit a selected range of wavelengths of total light radiation incident on the second surface 126 and substantially reflect a selected range of wavelengths of total light radiation incident on the second surface 126. Although the optical element 120 is shown as a single optical element, those skilled in the art will understand that the optical element 120 may include multiple optical elements arranged in any configuration from a wide variety of configurations. The material of the optical element 120 can be selected so that the transmission of light radiation at various wavelengths is at a specific rate. For example, the optical element 120 may have a transmittance of 50% or more at one or more wavelengths, depending on the material used.

[0039] As shown in Figure 2, light radiation entering the optical element 120 is reflected from the reflective surface portion 128 of the second surface 126. The surface portion 128 is configured to reflect or direct light radiation in both directions when configured as shown in Figure 2. In the illustrated embodiment, the optical element 120 is provided as a hemispherical lens in which surface portions 123 and 124 are parts of a sphere. Those skilled in the art will understand that the optical element 120 may be provided as any of the various shapes or types of lenses. These various shapes or types of lenses include, but are not limited to, ball lenses, half-ball lenses, elliptical lenses, hemispherical prism lenses, aspherical lenses, hyperhemispherical lenses, hypo hemispherical lenses, semi-elliptical lenses, GRIN lenses, plane mirrors, waveplates, beam splitters, prisms, diffraction gratings, Fresnel lenses, etc., or any combination thereof. Thus, surfaces 122 and 126 can be formed to match the shapes or types of lenses described above. In various embodiments, the optical element 120 can be formed from a variety of materials, including, but not limited to, glass, sapphire, plastic, silicon carbide, quartz glass, silicone (RTV), colored glass, and IR / UV optical materials such as silicon, zinc sulfide, germanium, arsenic triphosphate, barium fluoride, calcium fluoride, magnesium fluoride, zinc selenide, or any combination thereof. Those skilled in the art will understand that the optical element 120 can be formed from any variety of optical materials.

[0040] The first surface 122 of the optical element 120 (including surface portions 123 and 124) may be coated with at least one optical coating configured to reduce back reflection, increase transmittance, raise the laser-induced damage threshold (LIDT), or affect any other optical properties. In other embodiments, all or part of the first surface 122 may be coated with a reflective coating having a reflectance of at least 50%, at least 75%, or at least 90% with respect to the wavelength of light directed through the optical assembly 100. These coatings can be applied to the first surface 122 by any and no other process, including, but not limited to, physical vapor deposition, chemical vapor deposition, sputtering, etc. When provided as a reflective coating, the coating may include a single layer, for example, a dielectric film of aluminum, chromium, silver, gold, nickel, silicon dioxide, silicon nitride, magnesium fluoride, etc., or may consist essentially of the above single layer, or may include multiple layers or a Bragg reflector. When provided as an anti-reflective coating, the coating may include a nanotexture surface including nanowires, microwires, nanocones, nanodomes, and nanopillars applied by various processes. These various processes include electron beam lithography, chemical etching, vapor-liquid-solid growth, spin coating, or dip coating. Such a nanotexture coating or surface may be formed by laser patterning, selective laser ablation, or other forms of laser material processing or other types of processing, such as chemical vapor deposition. In another embodiment, the coating of the first surface 122 includes at least one interference structure, interference layer, or interference coating configured to filter or remove at least a portion of the wavelengths of light directed through the optical assembly 100.When applied in this manner, the layer or coating may be configured to act as a bandpass filter, highpass filter, lowpass filter, notch filter, or have any of these filtering properties for wavelengths of light directed through the optical assembly 100. In yet another embodiment, at least a portion of the first surface 122 may include a dichroic mirror. In various embodiments, such a dichroic mirror may be configured to substantially transmit a selected range of wavelengths of total light emission incident on the first surface 122 and substantially reflect a selected range of wavelengths of total light emission incident on the first surface 122. In various embodiments, the optical element 120 may be configured for total internal reflection of light from at least a portion of the internal reflective surface 126. Those skilled in the art will understand that the first surface 122 may be coated with any of the wide variety of optical coatings. The second surface 126 may include at least one interference structure, interference layer, or interference coating configured as a bandpass filter, lowpass filter, notch filter, highpass filter, or have any of these filtering properties for wavelengths of light directed through the optical assembly 100. Those skilled in the art will understand that the second surface 126 may be provided as or using any of the following: materials, coatings, structures, etc., similar to the first surface 122.

[0041] The passage 114 is configured to house an optical waveguide 130 configured to guide light radiation 140 from a first optical port 170 to an optical element 120 and from the optical element 120 to the first optical port 170. The waveguide 130 has a first end 134 defining the first optical port 170 and a second end 138 defining the first optical axis A1. In the illustrated embodiment, the waveguide 130 is provided as a single-clad optical fiber having a core and cladding, the core having a first diameter, and the optical element 120 having a radius such that the ratio of the core diameter to the lens radius is 10 or more. In various embodiments, the first end 134 and the second end 138 of the waveguide 130 are coated with an anti-reflective coating that acts to minimize back reflection from either surface. Alternatively, the first end 134 and the second end 138 may not be coated, or may be formed at an angle that reduces back reflection. In the illustrated embodiment, the second end 138 of the waveguide 130 may be positioned at a distance 139 formed within the relief 129 from the surface 122 of the optical element 120. In various embodiments, the distance 139 may be less than about 20 mm, or less than about 10 mm, or less than about 5 mm, or less than about 2 mm. The relief 129 may be filled with air or other gas, refractive index matching fluid, or refractive index matching adhesive. In other embodiments, the waveguide 130 may be provided as any various optical waveguide (e.g., optical rod, hollow optical rod, double-clad fiber, optical fiber bundle, light pipe, single crystal fiber, photonic crystal fiber, sapphire rod, homogenizer, etc., or any combination thereof). In one embodiment, the waveguide 130 has a light transmittance greater than 40%, but those skilled in the art will understand that the waveguide 130 may have any amount or percentage of light transmittance. Waveguide 130 may be held within passage 114 by adhesive or other retaining device or method. In various embodiments, the homogenizer may operate to randomize or partially randomize (e.g., by scattering) the direction and / or angle of rays leaving the homogenizer with respect to how rays enter the homogenizer.In various embodiments, such homogenizers may include solid optical rods, light pipes, and the like. Those skilled in the art will understand that various optical devices can be used as homogenizers.

[0042] In various embodiments, a protective window 125 may be inserted into the passage 118 and fixed in place (for example, mechanically or using one or more adhesives or other mounting means) to protect the components of the optical assembly 100 from the harsh environment of the process chamber. The window 125 may be provided as a planar optical component or lens formed from any of the optical materials enumerated herein with respect to the optical element 120. Those skilled in the art will understand that the protective window 125 is optional.

[0043] When the optical assembly 100 is configured as shown in Figure 2, the light radiation 140 is restricted to the range of the waveguide 130 until it exits the second end 138 of the waveguide 130. When the light radiation 140 enters the free space of the relief 129 (for example, when the relief 129 is filled with a gas such as air), the light radiation 140 may begin to diverge. The light radiation 140 is then collimated by the optical element 120, focused by the optical element 120 as it exits through the surface portion 124, and propagates along the optical axis A2 as light radiation 150 through the second optical port 172. The counterpropagated radiation 152 enters the optical port 172 and is directed by the optical element 120 into the waveguide 130 as counterpropagated radiation 142, which propagates through the first optical port 170.

[0044] In the illustrated embodiment, the optical assembly 100 is configured such that light radiation 140 (e.g., light having one or more wavelengths propagating from a light source (not shown)) enters the first optical port 170, is incident on the first portion 123 of the surface 122, is reflected from the portion 128 of the internal reflective surface 126, and exits through the second portion 124 of the surface 122 towards the second optical port 172 from the optical element 120. The passage 118 is configured so that the light radiation exiting through the second portion 124 of the curved surface 122 can exit the housing 110. The passage 118 may be filled with air or other gas, refractive index matching fluid, or refractive index matching adhesive. In one exemplary embodiment, when the optical assembly 100 is used with a thermographic optical fiber sensor system (e.g., to measure the temperature of the surface 32 of the object 30 shown in Figure 1), the light radiation 140 (also referred to herein as “excitation radiation 140”) includes wavelengths that act to excite the sensing element (e.g., a thermographic phosphor). Excitation radiation 140 (for example, from an optical source such as an LED or laser) enters the first optical port 170, propagates through the waveguide 130, enters the optical element 120 through the surface portion 123 of the surface 122, is reflected from the surface portion 128 of the internal reflective surface 126, propagates through the surface portion 124 of the surface 122, passes through the window 125, and thereby exits the second optical port 172 as excitation radiation 150. Once exited, the excitation radiation 150 propagates to the sensing element and excites the phosphor. When the phosphor emits luminescence (also referred to herein as "fluorescent"), luminescence radiation (also referred to herein as "emitted radiation" or "fluorescent emission") containing information related to the temperature of the sensing element propagates in the reverse direction toward the optical assembly 100 as emitted counterpropagated radiation 152. The emitted counterpropagated radiation 152 enters the second optical port 172, propagates through the surface portion 124 of the surface 122, is reflected from the surface portion 128 of the internal reflective surface 126, exits the optical element 120 through the surface portion 123, and propagates through the waveguide 130 as emitted counterpropagated radiation 142.The emitted counterpropagated radiation 142 exits the first optical port 170 and is routed at the first optical port 170 to other parts of the optical fiber sensor system (e.g., a detector configured to measure the characteristics of the counterpropagated radiation 142, including temperature-related information, e.g., the intensity attenuation rate of the emitted counterpropagated radiation 142). In the illustrated embodiment, the emitted counterpropagated radiation 142 / 152 has a different spectral power distribution from the excitation radiation 140 / 150.

[0045] In other embodiments, when the optical assembly 100 is used as a position sensor or presence sensor rather than a temperature sensing element, the radiation 150 can be incident on a test surface positioned, for example, at a distance from the optical assembly 100 in the direction of axis A2. In various embodiments, the radiation 150 can be reflected when the test surface is aligned with axis A2, in which case the counterpropagated radiation 152 / 142 can be detected at the first optical port 170. On the other hand, when the test surface is not aligned with axis A2, the radiation 150 does not hit the test surface and / or is not reflected from the test surface, and the counterpropagated radiation 152 / 142 is not detected at the first optical port 170. In various embodiments, the presence of counterpropagated radiation 142 at the first optical port 170 can provide a signal related to the presence or absence of the test surface above the optical assembly 100. In some position sensing or presence sensing embodiments, the spectral power distribution of the radiation 140 / 150 may be the same as or similar to the spectral power distribution of the counterpropagated radiation 152 / 142. In various embodiments, position detection or presence detection can be performed using one or more sensors, focusing on the times when a return signal or counter-propagated signal is present and absent. This provides information regarding the position or presence of the test surface relative to the positions of one or more sensors.

[0046] In other embodiments, the internal reflective surface 126 may be provided as a dichroic mirror, or coated with a dielectric coating that allows a portion of the light emission 140 to propagate through the surface 126 as transmitted radiation 160 (e.g., measured by a photodetector (not shown)), and the counterpropagated radiation 162 can propagate through the surface 126 into the optical assembly 100 and exit through the first optical port 170. Similarly, a portion of the counterpropagated radiation 152 can propagate through the surface 126 as transmitted radiation 180 (e.g., measured by a photodetector (not shown)), and the counterpropagated radiation 182 can propagate through the surface 126 into the optical assembly 100 and exit through the second optical port 172.

[0047] Figure 3 shows a cross-sectional view of an illustrative embodiment of an optical assembly 100 configured to change the propagation direction of light radiation 150 / 152 along an optical axis A2 at an angle greater than 90 degrees with respect to optical axis A1. The optical assembly 100 is provided as described above with respect to Figure 2, except that the second surface 126 of the optical element 120 is positioned at a different angle, and the passage 118 and window 125 may be larger and / or positioned so that the light radiation 150 / 152 can enter and exit the second optical port 172 of the optical assembly 100 along the optical axis A2 at the illustrated angle. In the illustrated embodiment, the optical element 120 (and thereby the angle of the second surface 126) is fixed at the illustrated angle, but in other embodiments, the orientation of the angle of the optical element 120 can be adjusted. Although not shown, in another embodiment, the second surface 126 may be provided as a dichroic mirror, as in Figure 2.

[0048] Figure 4 shows a cross-sectional view of an exemplary embodiment of an optical assembly 100 configured to change the propagation direction of light emission 150 / 152 along an optical axis A2 at an angle less than 90 degrees with respect to optical axis A1. The optical assembly 100 is provided in the same manner as described above with respect to Figure 3, except that the second surface 126 of the optical element 120 is positioned at a different angle, and the passage 118 and window 125 may be sufficiently large and / or positioned so that the light emission 150 / 152 can enter and exit the second optical port 172 along the optical axis A2 at the illustrated angle. In the illustrated embodiment, the optical element 120 is fixed at the illustrated angle, but in other embodiments, the angular orientation of the optical element 120 can be adjustable. Although not shown, in another embodiment, the second surface 126 may be provided as a dichroic mirror, as in Figure 2.

[0049] Figure 5 shows a cross-sectional view of an exemplary embodiment of the optical assembly 200. The optical assembly 200 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or a wide variety of sensors or sensor systems. The structure of the optical assembly 200 is the same as that of the optical assembly 100 described above. The optical assembly 200 includes at least one housing 210 having a first opening or passage 214 sized to accommodate a first optical waveguide 230 and a second opening or passage 215 sized to accommodate a second optical waveguide 260 inside. Internal reliefs 219 and 221 are also formed in the housing 210. An optical element accommodating passage or relief 229 configured to receive at least one optical element 220 is formed in the housing 210. The optical assembly 200 is configured to change the propagation direction of the light radiation 240 propagating along the first optical axis A1 to propagation as light radiation 250 along the second optical axis A2, as described herein (and the same applies to the opposite propagating light radiation 242 from the opposite propagating light radiation 252 in the reverse direction). Figure 5 shows an angle of 90 degrees between the first optical axis A1 and the optical axis A2, but the optical assembly 200 may be configured to change the propagation direction of the light radiation to any angle, and optionally, the angle may be adjustable.

[0050] The optical assembly 200 has a first optical port 270 and a second optical port 272. The first waveguide 230 has a first end 234 and a second end 238 that define both the first optical port 270 and the first optical axis A1. The second waveguide 260 includes a first end 264 and a second end 268 that define the second optical axis A2. The first waveguide 230 is configured to guide the light radiation 240 from the first optical port 270 to the optical element 220. The optical element 220 receives the light radiation 240, reflects it as light radiation 252 coupled into the second waveguide 260, and optionally focuses it. In the second waveguide 260, the light radiation propagates through the second waveguide 260 along the second optical axis A2 until it exits the second optical port 272. The counterpropagated radiation 252 enters the second optical port 272, where it propagates along the optical axis A2 through the waveguide 260 to the optical element 220, where it is reflected into the first optical waveguide 230 as counterpropagated light radiation 242 and optionally focused. The counterpropagated light radiation 242 propagates along the first optical axis A1 until it exits the first optical port 270. In various embodiments, the optical element 220 and the waveguides 230 and 260 may be provided as described above with respect to the optical element 120 and the optical waveguide 130 (along with all alternative forms, configurations, variations, and combinations thereof). Other structures or features of the optical assembly 200 may also be provided in a similar manner to that described above with respect to the optical assembly 100 (along with all alternative forms, configurations, variations, and combinations thereof).

[0051] Figure 6 shows a cross-sectional view of an exemplary embodiment of the optical assembly 300. The optical assembly 300 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or any of the many different types of sensors or sensor systems. Some parts of the structure of the optical assembly 300 are the same as those of the optical assemblies 100 and 200 described above. The optical assembly 300 is configured to change the propagation direction of the light radiation 340 propagating along the first optical axis A1 to propagation as light radiation 350 along the second optical axis A2 (and the same applies in the reverse direction from the counterpropagating light radiation 352 to the counterpropagating light radiation 342). Figure 6 shows an angle of 90 degrees between the first optical axis A1 and the second optical axis A2, but the optical assembly 300 may be configured to change the propagation direction of the light radiation to any angle.

[0052] The optical assembly 300 includes at least one housing 310 and at least one optical element 320. The optical element 320 includes a first surface 322, a first surface portion 323, a second surface portion 324, and a second reflective surface 326 having a reflective region 328. The optical assembly 300 has a first optical port 370 (first surface portion 323) and a second optical port 372 (second surface portion 324). The optical element 320 receives light radiation 340 propagating along the first optical axis A1 and reflects it as light radiation 350. The light radiation 350 propagates through the second optical port 372 along the second optical axis A2. The counterpropagated radiation 352 enters the second optical port 372 along the optical axis A2 and proceeds to the optical element 320, where it is reflected as counterpropagated light radiation 342. The opposing propagating light radiation 342 propagates along the first optical axis A1 and exits the first optical port 370. In various embodiments, the optical element 320 may be provided as described herein with respect to optical elements 120 and 220 (along with any alternative forms, configurations, modifications, and combinations thereof). Other structures or features of the optical assembly 300 may also be provided in a manner similar to that described herein with respect to optical assemblies 100 and 200 (along with any alternative forms, configurations, modifications, and combinations thereof).

[0053] Figure 7 shows a cross-sectional view of an exemplary embodiment of the optical assembly 400. The optical assembly 400 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or any of the many different types of sensors or sensor systems. Some parts of the structure of the optical assembly 400 are the same as those of the optical assemblies 100 and 200 described above. The optical assembly 400 incorporates several features configured to make the manufacture of the optical assembly 400 easier or less expensive than other embodiments described herein. These features include a two-piece housing (including housing portion 410 and housing portion 416), and a countersink 464 formed in the opening of the passage 414, configured to facilitate the insertion of the optical waveguide 430 into the passage 414. Multiple adhesive ports 460 may be formed in the housing portion 410, each adhesive port 460 including an optional chamfered portion 462. The adhesive ports 462 may be used to introduce adhesive to fix the optical waveguide 430 in the passage 414. In various embodiments, the optical assembly 400 may be constructed by positioning or bonding the optical element 420 within the housing portion 410 and covering or holding the optical element 420 in place with the housing portion 416. In the illustrated embodiment, a counterbore region 466 is formed around the optical element 420 within the housing portion 410 to create a groove that controls the amount of adhesive used to bond the optical element 420 to the housing portion 410, optionally. In various embodiments, the housing portion 416 may be formed from sheet metal, machined metal, or other housing materials as referred herein.

[0054] Those skilled in the art will understand that in various embodiments, the optical elements 420, the waveguides 430, and the optional windows 425, as well as their orientations with respect to the optical axes A1 and A2, may be provided as described herein with respect to the optical elements 120, 220, and 320 and the optical waveguides 130, 230, and 330, respectively (along with all alternative forms, configurations, variations, and combinations thereof). Furthermore, other structures or features of the optical assembly 400 may also be provided in a manner similar to that described herein with respect to the optical assemblies 100, 200, and 300 (along with all alternative forms, configurations, variations, and combinations thereof).

[0055] Figure 8 shows an illustrative embodiment of an optical sensor system 500 configured to detect and measure at least one property of the surface 32 of an object 30 (e.g., a semiconductor wafer, a wafer holder, or other part or equipment of wafer manufacturing). The optical sensor system 500 includes a processing unit 502 and an optical source 506 communicating with the processing unit 502 via a communication link 504, wherein the optical source 506 is configured to emit outgoing light radiation or a signal 508 (e.g., an optical excitation signal configured to cause luminescence of a phosphorescent sensing element) routed to a pair of optical assemblies 100 via an optical link 525. The optical source 506 may be provided as an LED, a super-luminescent diode (SLED), a laser, or a broadband light source. Those skilled in the art will understand that the optical source 506 may be provided as any of the wide variety of light sources. The optical sensor system 500 further includes a detector 514 configured to measure one or more properties of the return radiation or signal 512 and transmit measurement data representing those properties to a processing unit 502 via a communication link 516. The processing unit 502 is configured to provide a command (e.g., a command to emit an excitation signal 508) to the optical radiation source 506, receive, amplify or otherwise process the return signal 512 from the detector 514 to obtain measurement results (e.g., the temperature of the surface 32), and display those results or transmit them to another instrument or control system via a communication link 518.

[0056] In the illustrated embodiment, the optical sensor system 500 further includes an optical element 510 configured to direct an optical signal 508 to the optical assembly 100 via an optical link 525 and to direct a return signal to the detector 514 rather than the light source 506 (for example, to prevent harmful optical feedback effects). In the illustrated embodiment, the optical element 510 is an optical splitter having a partially reflective surface 511 formed thereon. In some embodiments, when the optical element 510 is provided as an optical splitter, the surface 511 may allow a portion of the counterpropagated radiation (for example, at a specific wavelength, a specific wavelength range, or a specific optical power) to pass through the partially reflective surface 511 as radiation 513 for various purposes. In other embodiments, the optical element 510 may be provided as an optical circulator.

[0057] The optical signal 508 is routed to the optical assembly 100 via the optical link 525 as radiation 540 propagating along the optical axis A1. The optical assembly 100, assembled together as shown in the figure, is configured to change the propagation direction of the radiation 540 (including the optical signal 508) propagating along the first optical axis A1 to propagation along a third optical axis A3 that is substantially parallel to the first optical axis A1 but offset from the first optical axis A1 (also referred to herein as “off-axis”), thereby routing the radiation 540 as radiation 560 (including the signal 508) to the sensing element 582 of the optical probe 580, where the sensing element 582 is in thermal communication with the surface 32 of the object 30.

[0058] In other embodiments, the first optical axis A1 does not have to be parallel to the third optical axis A3. Furthermore, the pair of optical assemblies 100 may be configured to change the propagation direction of the radiation 540 to any angle. The optical assembly 100 may be provided as any of the embodiments of optical assemblies 100, 200, 300, or 400 described herein with respect to Figures 2 to 7. In other embodiments, the optical assembly 100 may be provided as any of the embodiments of optical assemblies 600, 700, or 800 described herein with respect to Figures 9 to 14.

[0059] When the sensing element 582 is provided as a phosphor, the signals 508, radiates 540, 550, and 560 are provided as excitation radiation incident on the sensing element 582, which absorbs at least a portion of the radiation 560 and emits fluorescence emission (e.g., ultimately measured as a return signal 512 by the detector 514) as counterpropagated fluorescence emission 562 propagating in the reverse direction along the optical axis A3. The counterpropagated fluorescence emission 562 is reflected as fluorescence counterpropagated light emission 552 propagating along the optical axis A2. The fluorescence counterpropagated light emission 552 is reflected and propagates along the optical axis A1 as fluorescence counterpropagated radiation 542. The fluorescence counterpropagated radiation 542 is coupled in the optical link 525 and returns to the optical element 510, where it is directed to the detector 514. Generally, the excitation radiation and fluorescence emission have different optical power spectral distributions and different frequency components. In various embodiments, the counterpropagated signal may also include a portion of the excitation radiation, which in various embodiments may be separated from the fluorescence emission.

[0060] Figure 9 shows a cross-sectional view of an illustrative embodiment of the optical assembly 600. The optical assembly 600 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or a wide variety of sensors or sensor systems. In the illustrated embodiment, the optical assembly 600 is configured to change the propagation direction of light radiation propagating along a first optical axis A1 to propagation along a third optical axis A3 that is parallel to the first optical axis A1 but offset from the first optical axis A1 (also referred to herein as “off-axis”). In the illustrated embodiment, the optical assembly 600 includes a first housing portion 610 and two second housing portions 616. A passage 614 is formed in the first housing portion 610, and the passage 614 is sized to accommodate at least one optical waveguide 630. The optical waveguide 630 may be provided as waveguide 130 described above with respect to Figure 2, or as a waveguide having similar characteristics. The first housing portion 610 includes a first optical port 670 defined by a passage 618 formed in the housing 610 and a second optical port 672 defined by a second passage 619 formed in the first housing portion 610. In the illustrated embodiment, the second housing portion 616 is coupled to the housing 610, but the housing portion 616 may be formed integrally with the first housing portion 610. In the illustrated embodiment, an optional protective window 625 may be fixed to the passages 618 and 619 (in the same manner as the window 125 described above with respect to Figure 1). Two reliefs 629 are formed in the housing 610, each relief adjacent to the corresponding optical elements 620 and 621. Figure 9 shows the first optical axis A1 parallel to the third optical axis A3, but in other embodiments, the first optical axis A1 may not be parallel to the third optical axis A3.

[0061] The first optical element 620 and the second optical element 621 (having a refractive surface 622 and a reflective surface 626) are fixed within the housing 610 or to an additional housing portion 616. The optical elements 620 and 621 may be provided as any of the optical configurations, shapes, surfaces, materials, coatings, etc., described herein with respect to the optical element 120. In the illustrated embodiment, the optical elements 620 and 621 are identical, but those skilled in the art will understand that the optical elements 620 and 621 do not have to be identical.

[0062] The optical assembly 600 is configured to receive the light emission 640. The light emission 640 propagates along the first optical axis A1 into the first optical port 670, enters the first optical element 620, is reflected from the reflective surface 626, coupled into the optical waveguide 630, and propagates as light emission 650 along the second optical axis A2 through the optical waveguide 630 and enters the second optical element 620. In the second optical element, the light emission 650 is reflected from the reflective surface 626 and exits through the second optical port 672 as light emission 660 propagating along the third optical axis A3. The optical assembly 600 is also configured to receive the counterpropagated radiation 662. The opposingly propagated radiation 662 propagates along the third optical axis A3 through the second optical port 672, enters the second optical element 620, is reflected by the reflective surface 626 in the second optical element, propagates along the optical axis A2 through the waveguide 630, passes through the optical element 620, is reflected by the reflective surface 626 in the optical element 620, and propagates outward along the optical axis A1 from the first optical port 670 as light radiation 642. Figure 9 shows the orientation changes of the optical axes A1 / A2 and A2 / A3 as 90 degrees each, but these axes can be oriented at any angle to each other (as shown in Figures 3 and 4). In one embodiment, the angle between optical axis A1 and optical axis A2 is between 10 degrees and 170 degrees. In another embodiment, the angle between optical axis A1 and optical axis A2 is between 20 degrees and 160 degrees. In another embodiment, the angle between optical axis A1 and optical axis A2 is between 30 degrees and 150 degrees. In another embodiment, the angle between optical axis A1 and optical axis A2 is between 40 degrees and 130 degrees. In another embodiment, the angle between optical axis A1 and optical axis A2 is between 50 degrees and 120 degrees. In another embodiment, the angle between optical axis A1 and optical axis A2 is between 60 degrees and 110 degrees. In another embodiment, the angle between optical axis A1 and optical axis A2 is between 70 degrees and 100 degrees. In another embodiment, the angle between optical axis A1 and optical axis A2 is between 80 degrees and 90 degrees.

[0063] In one embodiment, the angle between optical axis A2 and optical axis A3 is between 10 degrees and 170 degrees. In another embodiment, the angle between optical axis A2 and optical axis A3 is between 20 degrees and 160 degrees. In another embodiment, the angle between optical axis A2 and optical axis A3 is between 30 degrees and 150 degrees. In another embodiment, the angle between optical axis A2 and optical axis A3 is between 40 degrees and 130 degrees. In another embodiment, the angle between optical axis A2 and optical axis A3 is between 50 degrees and 120 degrees. In another embodiment, the angle between optical axis A2 and optical axis A3 is between 60 degrees and 110 degrees. In another embodiment, the angle between optical axis A2 and optical axis A3 is between 70 degrees and 100 degrees. In another embodiment, the angle between optical axis A2 and optical axis A3 is between 80 degrees and 90 degrees.

[0064] To demonstrate at least some of the optical effects of the optical assembly 600, the light emission 640 is shown by a separate ray 641 that enters the first optical port 670 as a collimating ray. Ray 641 is then focused and / or coupled into the optical waveguide 630 by the optical element 620, as shown by ray 651. The light emission 650 begins to diverge as it exits the optical waveguide 630 into the free space of the relief 629, as shown by ray 655, is then collimated by the optical element 620, and exits the second optical port 672 as a collimating ray 661. The optical effects of the optical assembly 600 are also shown for the reverse case, when the counterpropagating radiation 662 enters the second optical port 672 as a collimating ray 663. The collimating ray 663 is reflected and coupled into the optical waveguide 630 by the optical element 620, as shown as ray 657, and as ray 657 exits the waveguide 630, it is shown as ray 653, which is reflected and propagates through the optical port 670 as collimating ray 643 propagating along the first optical axis A1.

[0065] Figure 10 shows a cross-sectional view of an example embodiment of an optical assembly 600, which is shown in Figure 9 but does not have a waveguide 630. In this embodiment, the light radiation is shown propagating in the free space between optical elements 620 and 621, entering the first optical port 670 as a divergent ray 641, which is reflected from the reflective surface 626 and collimated by the first optical element 620 as a collimated ray 651, which propagates along the second optical axis A2 to the second optical element 621, which is reflected and focused by the second optical element 621, and propagates as a converging ray 661 through the second optical port 672 along the third optical axis A3. The counterpropagated radiation 662 enters the second optical port 672 and propagates along the third optical axis A3 as a divergent ray 663. The divergent ray 663 is reflected and collimated by the second optical element 621 as the collimating ray 653 of the opposing propagated radiation 652. The ray 653 propagates along the second optical axis A2 to the first optical element 620, where it is reflected and focused as the converging ray 643 of the opposing propagated radiation 642. The converging ray 643 propagates along the first optical axis A1 and exits the first optical port 670.

[0066] Figure 11 shows a cross-sectional view of the optical assembly 600 shown in Figure 10. In this embodiment, the light emission entering the first optical port 670 is a divergent ray 641, which is reflected from the reflective surface 626 and collimated by the first optical element 620 as a collimated ray 651. The collimated ray 651 propagates along the second optical axis A2 to the second optical element 621, where it is reflected and focused as a ray 661. The ray 661 propagates through the second optical port 672 as light emission 660, which propagates along the third optical axis A3 into the optical guide 682 of the optical assembly 680. In the illustrated embodiment, the optical assembly 680 is an optical fiber temperature probe having a sensing element 684 that is in thermal communication with the object surface 32 of the object 30. The counterpropagating radiation 662 (for example, luminescent radiation having different spectral components from the optical radiation 660) propagates along the third optical axis A3 as a divergent ray 663 and enters the second optical port 672. The divergent ray 663 is reflected and collimated by the second optical element 620 as a collimating ray 653 of the counterpropagating radiation 652. The collimating ray 653 propagates along the second optical axis A2 to the first optical element 620, where it is reflected and focused as a converging ray 643 of the counterpropagating radiation 642. The converging ray 643 propagates along the first optical axis A1 and exits the first optical port 670.

[0067] Figure 12 shows a cross-sectional view of the optical assembly 600 shown in Figure 11. In this embodiment, the light radiation 640 entering the first optical port 670 is reflected as light radiation 650 from the reflective surface 626 of the optical element 620, propagates along the second optical axis A2 to the second optical element 621, is reflected by the second optical element 621, and propagates as light radiation 660 along the third optical axis A3 through the second optical port 672 into the sensing element 692 positioned at the sensing tip 690. Both the sensing tip 690 and the sensing element 692 are in thermal communication with the object surface 32 of the object 30. In this illustrated embodiment, components of the optical fiber temperature probe 680 are not required. The counterpropagated radiation 662 (for example, luminescent radiation having different spectral components from the light radiation 660) enters the second optical port 672, is reflected and collimated by the second optical element 620 as counterpropagated radiation 652, propagates along the second optical axis A2 to the first optical element 620, is reflected by the first optical element 620 as counterpropagated radiation 642, and the counterpropagated radiation 642 propagates along the first optical axis A1 and exits the first optical port 670.

[0068] Figure 13 shows a cross-sectional view of an exemplary embodiment of the optical assembly 700. The optical assembly 700 may be used as a component of a distance sensor, presence sensor, edge finder, temperature sensor, optical spectrum sensor, or any of the many different types of sensors or sensor systems. The optical assembly 700 includes a housing 710 in which a first passage 714 and a second passage 718 are formed. An optical element 720 is provided in the same manner as the optical element 120 described above with respect to the optical assembly 100, and has a first surface 722 and a reflective surface 726. An optical waveguide 730 having a first end 734 and a second end 738 is attached to a ferrule or other structural member 735 positioned in the first passage 714. The waveguide 730 defines a first optical port 770 and a first optical axis A1. In various embodiments, the optical element 720 and the waveguide 730 may be provided as described above with respect to the optical element 120 and the optical waveguide 130, respectively (along with any alternative forms, configurations, modifications, and combinations thereof). Other structures or features of the optical assembly 700 may also be provided in a manner similar to that described herein with respect to the optical assemblies 100, 200, 300, 400, and 600 (along with any alternative forms, configurations, modifications, and combinations thereof).

[0069] The optical assembly 700 is configured to change the propagation direction of the light radiation 740 propagating along the first optical axis A1 to propagation as light radiation 750 along the second optical axis A2, as described below (the same applies in the reverse direction to the counter-propagating light radiation 742 from the counter-propagating light radiation 752). The waveguide 730 is configured to guide the light radiation 740 from the first optical port 770 to the optical element 720. The optical element 720 receives the light radiation 740, reflects it as light radiation 750, and focuses it. The light radiation 750 propagates along the second optical axis A2 until it exits the second optical port 772. The counterpropagated radiation 752 can enter the second optical port 772 and propagate along the second optical axis A2 to the optical element 720, where it can be reflected and focused into the optical waveguide 730 as counterpropagated light radiation 742. The counterpropagated light radiation 742 propagates along the first optical axis A1 until it exits the first optical port 770. Figure 13 shows the angle between the first optical axis A1 and optical axis A2 as 90 degrees, but the optical assembly 700 may be configured to change the propagation direction of the light radiation to any angle, and optionally, the angle may be adjustable.

[0070] Figure 14 shows a cross-sectional view of an illustrative embodiment of the optical assembly 800. The optical assembly 800 may be used as a component of a distance sensor, presence sensor, edge finder, temperature sensor, optical spectral sensor, or any of the many different types of sensors or sensor systems. In the illustrated embodiment, the optical assembly 800 includes a housing 810 in which a first passage 814 and a second passage 815 are formed. An optical element 820 may be provided in a similar manner to the optical element 120 described above with respect to the optical assembly 100, and has a first surface 822 and a reflective surface 826. A first optical waveguide 830, attached to a ferrule or other structural member 835, is positioned within the first passage 814. A second optical waveguide 880, attached to a structural member or ferrule 885, is positioned within the second passage 815. In some embodiments, one or both of the ferrules 835, 885 may be attached to at least one rotating joint (not shown) that operates so that the waveguides 830, 880 can rotate in a plane perpendicular to the propagation direction of radiation 840 / 842, 850 / 852 or the optical axes A1 and A2. In various embodiments, the optical element 820 and the waveguides 830 and 880 may be provided as described above with respect to the optical element 120 and the optical waveguide 130, respectively (along with all alternative forms, configurations, modifications, and combinations thereof). Other structures or features of the optical assembly 800 may also be provided in a manner similar to that described herein with respect to the optical assemblies 100, 200, 300, 400, and 600 (along with all alternative forms, configurations, modifications, and combinations thereof).

[0071] The optical assembly 800 is configured to change the propagation direction of the light radiation 840 propagating along the first optical axis A1 to propagation as light radiation 850 along the second optical axis A2, as described below (the same applies in the reverse direction to the opposite propagating light radiation 842 from the opposite propagating light radiation 852). The first waveguide 830 has a first end 834 and a second end 838 defining the first optical axis A1. The second waveguide 880 includes a first end 884 and a second end 888 defining the second optical axis A2. The second end 884 of the second waveguide 880 defines the first optical port 870. The first waveguide 830 is configured to guide the light radiation 840 from the first optical port 870 to the optical element 820. Optical element 820 receives the light radiation 840, reflects it as light radiation 850 coupled into the second waveguide 880, and focuses it. The light radiation 850 propagates through the second waveguide 880 along the second optical axis A2 until it exits the second optical port 872. The counterpropagated radiation 852 enters the second optical port 872, propagates through the waveguide 880 along the optical axis A2 to optical element 820, where it is reflected and focused into the first optical waveguide 830 as counterpropagated light radiation 842, and the counterpropagated light radiation 842 propagates along the first optical axis A1 until it exits the first optical port 870. Figure 14 shows the angle between the first optical axis A1 and optical axis A2 as 90 degrees, but the optical assembly 800 may be configured to change the propagation direction of the light radiation to any angle, and optionally, the angle may be adjustable.

[0072] Figures 15 to 20 illustrate various exemplary embodiments of optical arrangements of waveguides and optical elements that may be suitable for use with optical assemblies 100, 200, 300, 400, and 600. These figures are intended to show only a few of the many possible arrangements of optical waveguides and optical elements that can be substituted for these arrangements in the embodiments described above. Those skilled in the art will understand that the components shown in Figures 15 to 20 can be substituted for each other in multiple combinations.

[0073] Figure 15 shows a cross-sectional view of an exemplary embodiment of the optical arrangement 900 (e.g., a portion of a reflective sensor). The optical arrangement 900 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or any of the many different types of sensors or sensor systems. The optical arrangement 900 includes at least one waveguide 930 and at least one optical element 920 having a first surface 922 and a reflective surface 926. Light radiation 940 propagates through the waveguide 930 (e.g., from a light source) and is reflected by the reflective surface 926 as light radiation 950, which propagates toward the surface to be detected (e.g., the surface 32 of the material to be detected (e.g., object 30)). Some of the rays of radiation 950 are reflected from the object surface 32 as reflected radiation or reflected rays 952 at the same angle as the incident rays with respect to the normal of the object surface 32. Other rays of radiation 950 are scattered by the object surface 32 as scattered radiation or scattered rays 954. Thus, the object surface 32 is a reflective surface that may produce some specular reflection and / or some diffuse reflection (e.g., due to scattering) depending on the material properties of the object 30 and the quality or roughness of the object surface 32. Scattered rays 954 may arrive from the object surface 32 over a range of angles due to the roughness of the object surface 32. A sensor using this optical configuration can detect changes from specular to diffuse reflection, or vice versa, of an object surface having rough and smooth or "mirror-like" areas as the sensor moves horizontally (i.e., parallel) to the object surface 32. The reflected rays 952 and scattered rays 954 are reflected by the reflective surface 926 as counterpropagated radiation 940 through the waveguide 930.

[0074] Figure 16 shows a cross-sectional view of an exemplary embodiment of the optical arrangement 1000. The optical arrangement 1000 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or any of the many different types of sensors or sensor systems. The light emission 1040 propagates through the optical waveguide 1030 (e.g., from a light source) and is incident on the first surface 1022 of the optical element 1020. In the illustrated embodiment, the optical element 1020 is provided as a half-ball lens. In other embodiments, the optical element 1020 may be provided as a ball lens, a cylindrical lens, an aspherical lens, a hyperhemispherical lens, a hypohemispherical lens, a semi-elliptical lens, or a hemispherical lens, etc., or any combination thereof. The light emission 1040 diverges when it leaves the waveguide 1030, then propagates into the lens 1020, is reflected from the second surface 1026, continues propagating through the lens 1020 before leaving the first surface 1022, is collimated at the first surface 1022, and propagates through free space as collimated light emission 1050. The condition for collimation is that the distance between the optical waveguide 1030 and the ball lens is BFL (Back Focal Length) = nD / (4(n-1)) - D / 2, where D is the diameter of the ball lens and n is the refractive index of the ball lens.

[0075] Figure 17 shows a cross-sectional view of an exemplary embodiment of the optical arrangement 1100. The optical arrangement 1100 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or any of the many different types of sensors or sensor systems. The optical arrangement 1100 generates divergent light emission from the optical waveguide 1130. This is done by changing the distance between the optical waveguide and the surface of a ball lens (or hemispherical lens or cylindrical lens). The light emission 1140 propagates through the optical waveguide 1130 (for example, from a light source) and is incident on the surface 1122 of the optical element 1120 (shown here as a hemispherical lens). The light emission 1140 diverges as it leaves the waveguide 1130, then propagates through the surface 1122 into the lens 1120, is reflected from the surface 1126, continues propagating through the lens 1120, and then propagates through the surface 1122 into free space as divergent light emission 1150.

[0076] Figure 18 shows a cross-sectional view of one embodiment of an optical arrangement 1200 that uses a Fresnel lens surface to focus light radiation. The optical arrangement 1200 may be used as a component of any of the following: a distance sensor, a presence sensor, an edge finder, a temperature sensor, an optical spectral sensor, or a wide variety of sensors or sensor systems. Light radiation 1240 propagates through the optical waveguide 1230 (for example, from a light source) and is incident on the first surface 1222 of the optical element 1220. In this embodiment, the first surface 1222 is provided as a Fresnel lens surface that functions to focus the light radiation 1240 as it passes through and propagates. The light emission 1240 diverges as it leaves the waveguide 1230, then propagates through the first surface 1222 into the optical element 1220, is reflected by the reflective surface 1226, passes through the optical element 1220, and continues to propagate through the second surface 1228, which is also provided as a Fresnel lens surface, and as a result the light emission is focused by the second surface 1228 and propagates into free space as focused light emission 1250.

[0077] Those skilled in the art will understand that the optical elements 920, 1120, and 1220 (or any combination thereof) may be used in any of the optical assemblies 100, 200, 300, 400, 600, 700, or 800.

[0078] The above description illustrates embodiments and examples of the present invention and should not be construed as a limitation of the invention. While a small number of specific embodiments and examples have been described with reference to the drawings, those skilled in the art will readily understand that many modifications to the disclosed embodiments and examples, and even other embodiments, are possible without substantially departing from the novel teachings and merits of the invention. Accordingly, all such modifications to the subject matter described herein are intended to fall within the scope of the invention as defined in the claims. For example, those skilled in the art will understand that it is possible to combine the subject matter of any sentence, paragraph, example, or embodiment with some or all of the subject matter of other sentences, paragraphs, examples, or embodiments, unless such combination is incompatible with each other. Accordingly, the scope of the invention should be determined by the appended claims, and anything equivalent to the claims is included within the scope of the invention.

Claims

1. At least one housing and The at least one optical element is at least partially disposed within the at least one housing and has at least one curved surface and at least one first reflective surface, Equipped with, The at least one optical element is configured to direct the first light emission incident on the first portion of the at least one curved surface so that it is at least partially reflected by at least a portion of the at least one first reflective surface and then exits the second portion of the at least one curved surface. An optical assembly wherein the light radiation incident on the first portion of the at least one curved surface has a first propagation direction along a first optical axis, and the light radiation exiting the second portion of the at least one curved surface has a second propagation direction along a second optical axis, the second propagation direction being different from the first propagation direction.

2. The optical assembly according to claim 1, wherein the angle between the first optical axis and the second optical axis is between 10 degrees and 170 degrees.

3. The optical assembly according to claim 1, wherein the at least one optical element includes a single optical element.

4. The optical assembly according to claim 1, wherein the at least one optical element is selected from the group consisting of a half-ball lens, a hyper-hemispheric lens, a hypo-hemispheric lens, a semi-elliptic lens, or a hemispheric lens.

5. The optical assembly according to claim 1, wherein the at least one optical element is selected from the group consisting of silica, quartz glass, soda-lime glass, borosilicate glass, sapphire, aluminum nitride, silicone (RTV), colored glass, IR / UV optical material (silicon, zinc sulfide, germanium, arsenic triphosphate, barium fluoride, calcium fluoride, magnesium fluoride, zinc selenide, silicon carbide, or plastic).

6. The at least one optical element is further configured to direct light radiation incident on the second portion of the at least one curved surface so that it exits the first portion of the at least one curved surface after being at least partially reflected or refracted by at least a portion of the first reflective surface. The optical assembly according to claim 1, wherein the light radiation incident on or leaving the first portion of the at least one curved surface has a first propagation direction, and the light radiation incident on or leaving the second portion of the at least one curved surface has a second propagation direction, the second propagation direction being different from the first propagation direction.

7. The optical assembly according to claim 1, wherein the at least one first reflective surface includes at least one reflective layer disposed over at least a portion of the at least one first reflective surface.

8. The optical assembly according to claim 7, wherein the at least one reflective layer includes at least one of a dichroic mirror, a total reflection mirror, at least one metal film, and at least one dielectric film or coating.

9. The optical assembly according to claim 1, further comprising an interference structure disposed over at least a portion of the at least one first reflective surface.

10. The optical assembly according to claim 1, wherein the at least one optical element is configured to collimate the beam of light radiation exiting the second portion of the at least one curved surface.

11. The optical assembly according to claim 1, wherein the at least one optical element is configured to focus the beam of light emission at a certain distance from the second portion of the at least one curved surface, and the focal length of the at least one optical element is between 1 mm and 350 mm.

12. The optical assembly according to claim 1, wherein the dimensions of the at least one housing perpendicular to the first propagation direction are 6 mm or less.

13. (i) A light source configured to emit a first light emission or output signal having a first spectral power distribution, (ii) A detector configured to measure a second light emission or return signal having a second spectral power distribution, Furthermore, The optical assembly according to claim 3, wherein the first light emission or output signal is incident on the first portion of the at least one curved surface, and the second light emission or return signal is exiting the first portion of the at least one curved surface.

14. The optical assembly according to claim 13, wherein the first spectral power distribution is different from the second spectral power distribution.

15. Further comprising a second reflective surface, The optical assembly according to claim 13, wherein the second reflective surface is configured to reflect at least a portion of the light radiation emanating from the second portion of the at least one curved surface and to direct the at least a portion of it back to the second portion of the at least one curved surface, and the second reflective surface is different from the at least one first reflective surface.

16. The optical assembly according to claim 13, wherein the optical assembly is at least one component selected from a temperature sensor, a presence sensor, or a distance sensor.

17. The detection element further comprises a detection element configured to emit the second light emission or return signal, The optical assembly according to claim 13, wherein the sensing element includes a phosphorescent material, and the optical assembly is at least a component of a temperature sensor.

18. The first optical waveguide further comprises having a first end and a second end, The second end is at least partially located within the at least one housing, and the first optical waveguide is (i) Enable the first light emission to propagate from the first end to the second end, (ii) enabling the second light emission to propagate from the second end to the first end, The optical assembly according to claim 1, configured such that the second end of the first optical waveguide communicates optically with the first portion of the at least one curved surface.

19. The optical assembly according to claim 18, wherein the first optical waveguide comprises at least one fiber bundle and at least one of an optical rod, a hollow optical rod, a double-clad fiber, a light pipe, a glass rod, or a sapphire rod.

20. The optical assembly according to claim 19, wherein at least one of the optical rod, the hollow optical rod, the double-clad fiber, the light pipe, the glass rod, or the sapphire rod is disposed between the at least one fiber bundle and the at least one optical element.

21. The optical assembly according to claim 18, further comprising a rotational joint configured to allow the first optical waveguide to rotate in a plane perpendicular to the first propagation direction.

22. Housing and A first optical waveguide defining a first optical axis, the first optical waveguide including a first end and a second end, the second end being at least partially located within the housing, and the first optical waveguide being configured to allow first light radiation to propagate from the first end to the second end and second light radiation to propagate from the second end to the first end, A first optical port through which the first light emission can pass and propagate, A second optical port through which the second light emission can pass and propagate, An optical element comprising at least one curved surface and at least one first reflective surface, (i) The second end of the first optical waveguide communicates optically with the first portion of the at least one curved surface of the at least one optical element, (ii) The first optical port communicates optically with the first portion of the at least one curved surface of the at least one optical element, (iii) The second optical port communicates optically with the second portion of the at least one curved surface of the at least one optical element, (iv) At least a portion of the first portion of the at least one curved surface differs from at least a portion of the second portion of the at least one curved surface, (v) The at least one optical element is configured to (a) direct the first light emission from the first optical waveguide to the second optical port, and (b) direct the second light emission from the second optical port to the first optical waveguide, An optical assembly comprising:

23. The optical assembly according to claim 22, further comprising a rotational joint configured to allow the first optical waveguide to rotate in a plane perpendicular to the first propagation direction.

24. At least one housing and A minimum one first optical element coupled to the minimum one housing and having at least one first curved surface and at least one first reflective surface, A second optical element coupled to the at least one housing communicates optically with the at least one first optical element and has at least one second curved surface and at least one second reflective surface, At least one optical waveguide that communicates optically with the at least one first optical element and the at least one second optical element, the at least one optical waveguide having a first end, a second end, and a second optical axis, Equipped with, The at least one first optical element is configured to receive a first light emission propagating along a first optical axis and to direct the first light emission towards the optical waveguide as a second light emission propagating along a second optical axis. An optical assembly wherein the at least one second optical element is configured to receive the second light radiation from the at least one optical waveguide and to direct the second light radiation as a third light radiation propagating along a third optical axis.

25. The at least one second optical element is configured to receive a fourth light emission propagating along the third optical axis and to direct the fourth light emission towards the optical waveguide as a fifth light emission propagating along the second optical axis. The optical assembly according to claim 24, wherein the at least one first optical element is configured to receive the fifth light emission from the at least one optical waveguide and to direct the fifth light emission as a sixth light emission propagating along the first optical axis.

26. The optical assembly according to claim 25, wherein the third light emission includes excitation emission propagating along the third optical axis to at least one sensing element, and the fourth light emission includes fluorescence emission propagating in opposition along the third optical axis.

27. The optical assembly according to claim 25, wherein the first light emission, the second light emission, and the third light emission include excitation emission propagated to at least one sensing element, and the fourth light emission, the fifth light emission, and the sixth light emission include fluorescence emission propagated in opposition to at least one detector.

28. The optical assembly according to claim 27, further comprising a light source configured to emit the excitation radiation propagating along the first optical axis.

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