Wafer-level composite lenses

Abstract

The wafer-level composite lens (200) relating to this disclosure has five coaxially aligned wafer-level lenses, and these five coaxially aligned wafer-level lenses are, in order, a negative first lens (202), a positive second lens (204), a positive third lens (206), a positive fourth lens (208), and a negative fifth lens (210), and the wafer-level composite lens has a substrate (214) disposed between the positive second lens (204) and the positive third lens (206), and a further substrate (216) disposed between the positive fourth lens (208) and the negative fifth lens (210).

Description

[Technical Field]

[0001] This disclosure generally relates to a wafer-level composite lens having five coaxially aligned wafer-level lenses, and an imaging device having the wafer-level composite lens. [Background technology]

[0002] In general, imaging devices capable of capturing three-dimensional (3D) information within a scene are extremely important for a wide range of application scenarios in both industrial and consumer electronics. A well-known example is the use of tracking sensors for augmented reality (AR) and virtual reality (VR) applications. For example, a world tracking sensor can sense the environment surrounding the user wearing the sensor, and even sense where the user is looking (similar to head tracking). Another example is a gesture tracking sensor, which can sense the location of the user's fingers and hands, as well as how they are moving. A further example is an eye-tracking sensor, which can precisely sense what the user is looking at and what they are focusing on. Based on the data sensed from the tracking sensors, a variety of functions aligned with the AR and VR context can be realized, such as presenting information to the user and executing commands based on the user's gestures and gaze. Exemplarily, such imaging devices provide a human-machine interface that allows the machine to "understand" what is in the outside world and what the user is looking at. Other application areas include modern smartphones, factory automation aimed at Industry 5.0, authentication systems for electronic payments, and facial recognition and authentication in Internet of Things (IoT) environments. [Overview of the project]

[0003] Improvements in imaging devices, particularly tracking sensors, can thus be especially crucial for the further advancement of several technologies. [Brief explanation of the drawing]

[0004] In the figures, similar reference letters generally refer to the same part across different figures. The figures are not necessarily to scale; instead, the focus is on illustrating the general principles of the present invention. In the following descriptions, various aspects of the present invention will be described with reference to the following figures.

[0005] [Figure 1A] This diagram schematically illustrates negative lenses in various configurations. [Figure 1B] This figure schematically illustrates positive lenses in various configurations. [Figure 2A] This figure schematically illustrates wafer-level composite lenses in various configurations. [Figure 2B] This figure schematically illustrates wafer-level composite lenses in various configurations. [Figure 3A] This figure schematically illustrates one embodiment of a wafer-level composite lens relating to various configurations. [Figure 3B] This figure schematically illustrates one embodiment of a wafer-level composite lens relating to various configurations. [Figure 3C] This figure schematically illustrates one embodiment of a wafer-level composite lens relating to various configurations. [Figure 3D] This figure schematically illustrates one embodiment of a wafer-level composite lens relating to various configurations. [Figure 3E] This figure schematically illustrates one embodiment of a wafer-level composite lens relating to various configurations. [Figure 3F] This figure schematically illustrates one embodiment of a wafer-level composite lens relating to various configurations. [Figure 3G] This figure schematically illustrates one embodiment of a wafer-level composite lens relating to various configurations. [Figure 4A]This figure schematically illustrates an imaging device according to one embodiment. [Figure 4B] This figure schematically illustrates an imaging device according to one embodiment. [Figure 4C] This figure schematically illustrates an imaging device according to one embodiment. [Figure 5A] This graph illustrates the characteristics of wafer-level composite lenses in various configurations. [Figure 5B] This graph illustrates the characteristics of wafer-level composite lenses in various configurations. [Figure 5C] This graph illustrates the characteristics of wafer-level composite lenses in various configurations. [Figure 5D] This graph illustrates the characteristics of wafer-level composite lenses in various configurations. [Figure 5E] This graph illustrates the characteristics of wafer-level composite lenses in various configurations. [Modes for carrying out the invention]

[0006] The accompanying drawings, referenced in the following detailed description, illustrate, by illustration, specific details and embodiments of how the present invention may be implemented. These embodiments are described in sufficient detail to enable implementation by persons skilled in the art. Other embodiments may be utilized, and structural, logical, and electrical modifications can be made without deviating from the technical scope of the present invention. These various embodiments are not necessarily mutually exclusive, and certain embodiments can be combined with one or more other embodiments to form new embodiments.

[0007] Generally, tracking sensors for augmented reality and / or virtual reality will be camera-based field-of-view sensors operating in the visible and / or near-infrared (NIR) spectral bandwidths, from the perspective of human vision. Imaging devices for such applications will typically incorporate a compact camera module (CCM) that senses light and generates corresponding sensing data. As new generations of imaging devices advance, there is a constant demand for miniaturization of their mechanical, optical, and electrical components. Designers are craving "inconspicuous" sensors.

[0008] Various requirements arising from the application are typically considered desirable or achievable when designing a camera-based tracking sensor. These design requirements may include small size, especially a small footprint; a high frame rate, for example, on the order of several hundred hertz, to enable smooth tracking of user eye movements and gestures; sensing robustness, such as a high signal-to-noise ratio (SNR) and / or low latency (e.g., a short time span between a gesture and its corresponding digital indication, i.e., the indication that it is an event that the system should respond to); the ability to operate in indoor and outdoor environments; low power consumption; and low material costs.

[0009] For these reasons, camera-based tracking sensors typically incorporate CMOS image sensors (CIS), where CMOS stands for complementary metal oxide semiconductor. Desired characteristics of a CMOS image sensor may include a small (global shutter) pixel size, which can reduce the footprint and achieve higher resolution and reduced power consumption. Another desirable characteristic of a CMOS image sensor may be high quantum efficiency, such as high quantum efficiency in the NIR spectral bandwidth, which can enable faster frame rates and increased signal-to-noise ratio (SNR). A further example of a desirable characteristic of a CMOS image sensor may be ease of integration within an integrated circuit, which can lead to smaller chip sizes and lower costs.

[0010] The camera-based tracking sensor may further incorporate an optical lens module that collects light from the sensor's field of view and directs the collected light to an image sensor (e.g., a CMOS image sensor). This disclosure may relate to providing several desirable characteristics for the optical lens module, including, for example, a small image diameter and lens flange, which may enable a reduced footprint and a shorter focal length (similar to that of a micro-optical system). Another example of a desirable characteristic for the optical lens module may be a low f-number (e.g., the ratio of focal length to aperture size), which may enable a high frame rate and low power consumption, as well as improved signal-to-noise ratio in low light conditions. A further example of a desirable characteristic for the optical lens module may be easy integration with a compact camera module, for example, the optical system module may be reflow solderable.

[0011] The present disclosure relates to, for example, a wafer-level compound lens designed with a small imaging device for tracking-related applications in mind. That is, the present disclosure relates to the configuration of a wafer-level compound lens that provides desirable characteristics, such as characteristics like a low f-number, short total track length, reflow compatibility, etc., that are desired for a camera-based tracking sensor. The present disclosure can thus be based on an understanding of what types of wafer-level lenses should be used and in what order the wafer-level lenses should be arranged to provide a wafer-level compound lens having advantageous characteristics, such as those for integration into a camera-based tracking sensor.

[0012] According to various aspects, the wafer-level compound lens can be provided with five coaxially aligned wafer-level lenses, and the order of those five coaxially aligned wafer-level lenses can be a negative first lens, a positive second lens, a positive third lens, a positive fourth lens, and a negative fifth lens. The wafer-level compound lens can further have a substrate disposed between the positive second lens and the positive third lens and a further substrate disposed between the positive fourth lens and the negative fifth lens.

[0013] The present disclosure can be based on the understanding that such a wafer-level lens arrangement (exemplarily such a wafer-level lens order) enables high-contrast (ultra-) wide-field-of-view (full angle α) imaging onto a small digital image sensor chip. That is, the wafer-level compound lens can be understood as a wafer-level optical lens system having three individual lens wafers (see FIG. 2A) and designed such that a reduction in the total (x, y) footprint of the lens (and thus the camera module containing the compound lens) is achieved.

[0014] In the context of small-footprint optical systems, wafer-level optics is the technology for creating miniature optical components, such as wafer-level lenses. Wafer-level optics exemplifies the use of optical component manufacturing technologies specific to the semiconductor industry. Wafer-level optics is widely used for camera modules, for example, for integration into portable devices such as tablets and smartphones. Overall, aspects of wafer-level optics and corresponding manufacturing technologies are well-known in the present art. A brief explanation is provided here to introduce the aspects of this disclosure.

[0015] The foundation of wafer-level optics lies in various processes specific to semiconductor manufacturing, such as thin-film deposition, lithography, etching, molding, and imprinting. For example, in wafer-level optics, molds can be used to create optical elements, enabling mass production. In summary, in wafer-level optics, optical components can be imprinted at the wafer level, and then the final product can be assembled by stacking individual optical component layers. The resulting optical module can then be finally coupled, for example, bonded, to an image sensor (e.g., a CMOS image sensor) at the wafer level. In this way, wafer-level optics can produce optical modules with a smaller footprint compared to other manufacturing technologies.

[0016] In wafer-level optics technology for fabricating optical components, a master stamp designed according to the configuration (e.g., shape, size, etc.) of the optical component to be fabricated can be incorporated. The master stamp allows for the transfer of a desired pattern into a curable material, such as an optical polymer, and then curing by irradiation with ultraviolet (UV) light. A suitable method for wafer-level optics is so-called "step-and-repeat UV imprint lithography," a method in which individual molds for optical components are replicated on a substrate (e.g., a wafer) using high-precision alignment. A stamp (e.g., a master stamp or corresponding work stamp) defines the shape of the curable polymer to be deposited on the substrate, and subsequent irradiation (e.g., UV light) allows the polymer to be cured in the desired shape. Typical deposition methods include paddle ejection and inkjet ejection.

[0017] After curing, further processing steps can be performed to complete the optical component. These further processing steps can be performed at the wafer level, thereby providing an efficient and streamlined optical component finishing procedure. These further processing steps may include, for example, demolding, cleaning, polishing, edge removal, covering, and stacking. Wafer-level optics can incorporate the stacking of wafers into which individual optical components are incorporated, for example by wafer bonding, to produce an optical module having a desired number and arrangement of optical elements. Wafer-level optics can further incorporate the dicing of the wafer stack to produce individual optical modules, for example, which can be arranged and coupled to an image sensor.

[0018] In the context of this disclosure, the use of the wafer-level composite lens described herein as an optical module within a tracking sensor can be particularly referenced, as it may represent the most important use case (e.g., in terms of miniaturization enabled by the proposed design). However, as you can see, the wafer-level composite lens described herein can also be introduced (e.g., integrated) into other types of imaging devices where overall miniaturization of the optical module may be advantageous. Further examples of imaging devices into which the wafer-level composite lens may be integrated include time-of-flight sensors, stereo vision sensors, and disparity-based sensors.

[0019] Figures 1A and 1B schematically show individual wafer-level lenses 102a and 102b in various embodiments. Wafer-level lenses 102a and 102b can serve as individual building blocks for providing a wafer-level composite lens (see, for example, Figure 2A) according to the design proposed in this application. As discussed earlier, wafer-level lenses 102a and 102b can be fabricated using wafer-level optical technologies such as UV molding and lithography. For simplicity, wafer-level lenses 102a and 102b are sometimes simply referred to as lenses 102a and 102b.

[0020] In various embodiments, as shown in Figure 1A, the wafer-level lens 102a can be configured as a plano-concave lens. In this configuration, the lens 102a can have a flat surface (e.g., a plane) 106a and a concave surface 108a. By making the lens 102a a negative lens, it can have, for example, a negative focal length 110a (the focal length is shown as the distance between the center of the lens 102a and the focal point 112a). The plano-concave lens 102a can be configured to provide beam expansion, as depicted in Figure 1A, for example, to cause parallel incident light rays to diverge on the exit side, thereby making it possible to increase the focal length of the optical system. Considering the concave surface 108a, the plano-concave lens 102a will, for example, be thicker at the edges than in the center.

[0021] In various embodiments, as shown in Figure 1B, the wafer-level lens 102b can be configured as a plano-convex lens. In this configuration, the lens 102b can have a flat surface (e.g., a plane) 106b and a convex surface 108b (e.g., a sphere). By making the lens 102b a positive lens, it can have, for example, a positive focal length 110b (the focal length is shown as the distance between the center of the lens 102b and the focal point 112b). The plano-convex lens 102b can be configured to bring about beam focusing, as depicted in Figure 1B, for example, to be able to converge parallel incident light rays on the exit side. Considering the convex surface 108b, the plano-convex lens 102b will, for example, be thicker in the center than at the edges.

[0022] As you can see, wafer-level optical elements are not limited to the creation of plano-concave lenses 102a or plano-convex lenses 102b, but can be extended to lenses with other profiles (for example, lens portions of different shapes). However, the embodiments of this disclosure can be based on the understanding that, in principle, a combination of plano-concave lenses 102a and plano-convex lenses 102b is sufficient to provide wafer-level composite lenses with a wide field of view, and that there is no need to incorporate more complex lens profiles (e.g., gull-wing profiles).

[0023] The wafer-level lenses 102a and 102b may be formed on a substrate 104a and 104b, for example, a wafer, or coupled thereto. For example, the lenses 102a and 102b can be formed on the substrate 104a and 104b, for example, the lenses 102a and 102b can be in direct physical contact with the substrate 104a and 104b. The substrates 104a and 104b may contain or be made of some suitable refractive material, for example, glass (e.g., glass silicate or alumina glass silicate) or polymer. In certain embodiments, the substrates 104a and 104b may be glass wafers. The lenses 102a and 102b may contain some suitable material for fabricating a wafer-level optical system. For example, lenses 102a and 102b may contain or be made of a polymer material, such as any suitable UV-curable polymer material including thiolene polymers, acrylate resins, epoxy polymers, etc.

[0024] Generally, the materials of lenses 102a, 102b and / or substrates 104a, 104b should be adapted according to the wavelength range in which the lenses operate. In various embodiments, lenses 102a, 102b and / or substrates 104a, 104b may contain or be made of materials configured for the visible range (e.g., 380nm to 700nm) or the near-infrared range (e.g., 800nm ​​to 2500nm). As a numerical example, lenses 102a, 102b and / or substrates 104a, 104b may contain or be made of materials configured to exhibit a transmittance of more than 90%, for example, more than 94%, within the above range. However, as you can see, the materials of lenses 102a, 102b and / or substrates 104a, 104b can also be designed for other wavelength ranges, such as the ultraviolet range (e.g., the range of 100nm to 400nm).

[0025] In certain embodiments, lenses 102a and 102b may be manufactured by polymer-on-glass fabrication (e.g., when substrates 104a and 104b are glass-filled or made of glass). In this configuration, lenses 102a and 102b may be, for example, hybrid glass-polymer lenses, i.e., the robustness of substrates 104a and 104b may enhance the stability of lenses 102a and 102b and facilitate their handling during fabrication. In other embodiments, lenses 102a and 102b may be monolithic polymer lenses (e.g., when substrates 104a and 104b contain or are made from a polymer, such as a UV-curable polymer), thereby reducing the fabrication process.

[0026] The dimensions of lenses 102a, 102b (and / or substrates 104a, 104b) should be adapted within the normal range of wafer-level optical technology, depending on the desired end application of the lenses 102a, 102b. For example, the thickness of substrates 104a, 104b can be in the range of 100 μm to 1 mm, for example, 200 μm to 500 μm. The thickness of lenses 102a, 102b (e.g., minimum thickness at the edge or center, depending on the type of lens) can be in the range of 5 μm to 100 μm, for example, 10 μm to 50 μm. As a further example, the diameter of lenses 102a, 102b (e.g., diameter of concave or convex portion) can be in the range of 100 μm to 10 mm, for example, 500 μm to 1 mm. The thickness of lenses 102a and 102b would be, for example, the height of the polymer material measured from the surface of the substrate, such as the sagittal height, plus the polymer base layer.

[0027] Figures 2A and 2B schematically show wafer-level composite lenses 200 in various embodiments. These wafer-level composite lenses 200 can be used in imaging devices, for example, in imaging devices capable of three-dimensional imaging. For example, the wafer-level composite lens 200 can be used in tracking sensors, such as world tracking sensors, gesture tracking sensors, and / or eye tracking sensors. The wafer-level composite lens 200 can also be simply referred to as the composite lens 200. The wafer-level composite lens 200 can be manufactured using wafer-level technologies, such as deposition (e.g., polymeron glass), UV mold replication, and wafer-to-wafer alignment and stacking. Thus, the composite lens 200 can be fabricated using cost-effective and scalable (micro) optical system fabrication technologies.

[0028] The wafer-level composite lens 200 may have five coaxially aligned wafer-level lenses 202, 204, 206, 208, and 210. For example, these five wafer-level lenses 202 to 210 can be arranged (aligned) along the optical axis 220 of the wafer-level composite lens 200. The individual optical axes of these five wafer-level lenses 202 to 210 can be overlapped (completely) with each other, and for example, their individual optical axes can be aligned with each other. For example, these five wafer-level lenses 202 to 210 can be aligned with the optical axis 220 of the wafer-level composite lens 200. In this way, the wafer-level composite lens 200 can be a wafer-level optical system lens system, for example, a wafer-level lens stack (e.g., one having a stack (laminated) of three individual lens wafers as will be discussed in detail below).

[0029] These five coaxially aligned wafer-level lenses may include, in order, a negative first lens 202, a positive second lens 204, a positive third lens 206, a positive fourth lens 208, and a negative fifth lens 210. This disclosure is based on the understanding that such a wafer-level lens arrangement enables imaging functionality for small imaging devices (e.g., small tracking sensors) while making the overall design of the composite lens 200 compact. In certain embodiments, the wafer-level composite lens 200 is composed of these five wafer-level lenses 202-210, and illustratively, the wafer-level composite lens 200 may be without further lenses (e.g., additional wafer-level lenses). In other embodiments, a further (sixth) lens may be provided, as will be discussed in detail in relation to Figure 3C.

[0030] In various configurations, the five wafer-level lenses 202 to 210 can be arranged in the order described above, from the object plane of the composite lens 200 to the image plane of the composite lens 200. For example, the negative first lens 202 may be the lens closest to the object plane of the composite lens 200 (e.g., during operation), and the negative fifth lens 210 may be the lens closest to the image plane of the composite lens 200 (e.g., during operation).

[0031] The negative first lens 202 and the negative fifth lens 210 can generally be configured as lens 102a as described in relation to Figure 1A. For illustrative purposes, the negative first lens 202 and the negative fifth lens 210 can be the first plano-concave lens 202 and the fifth plano-concave lens 210. The positive second lens 204, the positive third lens 206, and the positive fourth lens 208 can generally be configured as lens 102b as described in relation to Figure 1B. For illustrative purposes, the positive second lens 204, the positive third lens 206, and the positive fourth lens 208 can be the second plano-convex lens 204, the third plano-convex lens 206, and the fourth plano-convex lens 208.

[0032] Starting with the arrangement shown in Figure 2A, the overall optical function of the wafer-level composite lens 200 can be assembled by adapting the individual characteristics of these lenses, as will be discussed in detail later. In summary, as shown in Figure 2B, the composite lens 200 can be configured to focus light onto the image plane 224 (and therefore onto the image sensor; see also Figures 4A to 4C). Illustratively, the composite lens 200 can be configured (overall) to collect light (illustratively, light rays) and direct / focus the collected light onto the image plane 224. The arrangement of diverging and converging lenses is designed, in particular, to provide a wide field of view and high resolution suitable for imaging applications.

[0033] This disclosure can be based on the understanding that such wafer-level lens arrays can provide advantageous characteristics, such as superior contrast, robustness, and aberrations, making them suitable for use in small imaging devices without the need to incorporate more complex lens profiles. For example, in the lens array proposed in this application, the first and last lenses (negative first lens 202 and negative fifth lens 210) can have no inflection points along their lens profiles.

[0034] In various embodiments, the negative first lens 202 can be positioned facing the positive second lens 204. For example, the concave portion of the first lens 202 can be positioned facing the convex portion of the second lens 204. The positive third lens 206 can be positioned facing the positive fourth lens 208. For example, the convex portion of the third lens 206 can be positioned facing the convex portion of the fourth lens 208.

[0035] The recess of the first lens 202 can be positioned away from the field of view of the wafer-level composite lens 200 (e.g., away from the object surface of the composite lens 200). The recess of the fifth lens 210 can be positioned away from the field of view of the wafer-level composite lens 200. For example, the recess of the fifth lens 210 can be positioned away from the flat portion of the positive fourth lens 208. The flat portion of the positive fourth lens 208 can be positioned facing the flat portion of the negative fifth lens 210. The convex portion of the third lens 206 can be positioned away from the flat portion of the positive second lens 204. For example, the flat portion of the positive second lens 204 can be positioned facing the flat portion of the positive third lens 206.

[0036] In various embodiments, each lens 202-210 can be arranged on a corresponding substrate (e.g., a glass wafer or other suitable substrate as discussed in relation to Figures 1A and 1B). In this case, the wafer-level composite lens 200 may have a (first) substrate 212 on which the negative first lens 202 is arranged on the surface. The wafer-level composite lens 200 may further have a (second) substrate 214 arranged between the positive second lens 204 and the positive third lens 206. The wafer-level composite lens 200 may further have a (third) substrate 216 arranged between the positive fourth lens 208 and the negative fifth lens 210.

[0037] In various embodiments, some of these lenses can share the same substrate. For example, the positive fourth lens 208 and the negative fifth lens 210 can be formed on opposite sides of the same (third) substrate 216. For example, the positive fourth lens 208 can be formed on the first surface of the substrate 216 and the negative fifth lens 210 can be formed on the second surface of the substrate 216. The first and second surfaces can be located on opposite sides of each other in the direction along the optical axis 220. As an alternative example, the positive second lens 204 and the positive third lens 206 can be formed on opposite sides of the same (second) substrate 214. For example, the positive second lens 204 can be formed on the first surface of the substrate 214 and the positive third lens 206 can be formed on the second surface of the substrate 214, that is, on the surface opposite to the first surface. However, as you can see, in principle, lenses 202 to 210 can also be formed on separate substrates instead.

[0038] In various embodiments, the substrate shared between the two lenses can be a monolithic substrate, for example, a single wafer. This configuration provides a more robust structure. In other embodiments, the substrate shared between the two lenses can be formed by integrally bonding two substrates. This configuration provides a more flexible manufacturing process, allowing the lenses to be fabricated separately and then their substrates to be integrally bonded.

[0039] In one configuration example, the (second) substrate 214 between the positive second lens 204 and the positive third lens 206 may have a first substrate portion 218a coupled to the second substrate portion 218b. For example, the first substrate portion 218a and the second substrate portion 218b may be stacked on top of each other. In this configuration, the positive second lens 204 will be formed on the (first) surface of the first substrate portion 218a, and the positive third lens 206 will be formed on the (second) surface of the second substrate portion 218b. The (first) surface of the first substrate portion 218a will be on the opposite side of the (second) surface of the second substrate portion 218b in the direction along the optical axis 220. By forming the substrate 214 from two separate (stacked) portions, simple integration of additional components along its optical path becomes possible, as will be discussed in detail in relation to Figure 3D. However, as you can see, in other embodiments, the (second) substrate 214 may be a monolithic substrate.

[0040] In one configuration example, the (third) substrate 216 between the positive fourth lens 208 and the negative fifth lens 210 may be a monolithic substrate. In other embodiments, the (third) substrate 216 between the positive fourth lens 208 and the negative fifth lens 210 may have a first substrate portion that is integrally bonded (e.g., laminated) with the second substrate portion, as described above with respect to the (second) substrate 214.

[0041] As mentioned above, in a wafer-level lens array, the individual characteristics of lenses 202-210 can be adjusted, for example, in terms of material properties and / or optical properties, to suit the optical function of the wafer-level composite lens 200 (e.g., to suit imaging in an imaging device in which the wafer-level composite lens 200 will be integrated). Below, we describe various parameters that have been shown to improve the optical function of the composite lens 200. However, as you can see, in principle, it is also possible to maintain the overall structure / arrangement of the composite lens 200 while using other parameters (e.g., different materials, different dimensions, etc.).

[0042] In various embodiments, the refractive index and / or Abbe number of at least one lens 202-210, for example, the material of each lens 202-210, can be adapted to optimize the optical function of the wafer-level composite lens 200. Generally, the material of each lens 202-210 will have its own refractive index and its own Abbe number (e.g., the first material of the negative first lens 202 has a first refractive index and a first Abbe number, the second material of the positive second lens 204 has a second refractive index and a second Abbe number, and so on).

[0043] In this application, the term "refractive index" is used to describe the absolute refractive index of a material, or, more precisely, the ratio of the speed of light in a vacuum to the speed of light within that material. Various methods exist for measuring the refractive index of materials, such as those using refractometers (e.g., Abbelifractometers). As you can understand, the comparison of refractive indices between different materials as used in this application refers to a comparison of the individual refractive indices at the same wavelength.

[0044] The term "Abbe number" can be used to describe the degree of light dispersion in transparent materials, as is well known in this technical field, and, more precisely, the change in refractive index with respect to wavelength. The Abbe number can represent the dispersion ability of a material; for example, a smaller Abbe number indicates higher dispersion, while a larger Abbe number indicates lower dispersion. The Abbe number can also be called the "V number."

[0045] In this application, the terms "refractive index of a lens" or "Abbe number of a lens" can be understood to refer to "the refractive index of the material of the lens" and "the Abbe number of the material of the lens."

[0046] In various embodiments, the (second) refractive index n2 of the (second) material of the positive second lens 204 can be made higher than the (first) refractive index n1 of the (first) material of the negative first lens 202. The (first) Abbe number V1 of the (first) material of the negative first lens 202 can be made greater than the (second) Abbe number V2 of the (second) material of the positive second lens 204. For example, the (second) refractive index n2 may be at least 10% higher than the (first) refractive index n1, for example, at least 20% higher, or for example, at least 30% higher. Alternatively, the (first) Abbe number V1 may be at least 10% greater than the (second) Abbe number V2, for example, at least 20% greater, or for example, at least 30% greater.

[0047] When these relationships are considered in isolation or in combination with further relationships described below, it was found that they can lead to efficient imaging (or more generally contribute to efficient imaging), and that aberrations and distortions in the composite lens 200 can be significantly reduced.

[0048] Additionally or alternatively, the (third) refractive index n3 of the (third) material of the positive third lens 206 and the (fourth) refractive index n4 of the (fourth) material of the positive fourth lens 208 can be equal to the (first) refractive index n1 of the (first) material of the negative first lens 202. The (third) Abbe number V3 of the (third) material of the positive third lens 206 and the (fourth) Abbe number V4 of the (fourth) material of the positive fourth lens 208 can be equal to the (first) Abbe number V1 of the (first) material of the negative first lens 202. In a preferred configuration, these relationships can be achieved by using the same material for the three lenses, thereby simplifying the manufacturing process. Alternatively, these relationships may be achieved by selecting different types of materials that provide the same properties in terms of refractive index and Abbe number.

[0049] Additionally or alternatively, the refractive index n5 of the (5th) material of the negative 5th lens 210 can be higher than the refractive index n1 of the (1st) material of the negative 1st lens 202. For example, the refractive index n5 of the negative 5th lens 210 can be equal to the refractive index n2 of the positive 2nd lens 204. The (1st) Abbe number V1 of the negative 1st lens 202 can be greater than the (5th) Abbe number V5 of the (5th) material of the negative 5th lens 210. For example, the (5th) Abbe number V5 of the negative 5th lens 210 can be equal to the (2nd) Abbe number V2 of the positive 2nd lens 204. For example, the refractive index n5 can be at least 10% higher than the (1st) refractive index n1, for example, at least 20% higher, for example, at least 30% higher. As an alternative example, the (first) Abbe number V1 can be made at least 10% larger than the (fifth) Abbe number V5, for example, at least 20% larger, for example, at least 30% larger.

[0050] In summary, the promising relationship between the refractive indices of wafer-level lenses 202 to 210 can be expressed as n2=n5>n1=n3=n4. Correspondingly, the promising relationship between the Abbe numbers of wafer-level lenses 202 to 210 can be expressed as V1=V3=V4>V2=V5. As a numerical example, the refractive index n2 of the positive second lens 204 and the refractive index n5 of the material of the negative fifth lens 210 can be in the range of 1.60 to 1.70, for example, refractive indices n2 and n5 can be set to 1.62. As a further numerical example, the Abbe number V2 of the positive second lens 204 and the Abbe number V5 of the negative fifth lens 210 can be in the range of 20 to 30, for example, Abbe numbers V2 and V5 can be set to 25. For example, these relationships can be achieved by using commercially available polymers that provide the desired refractive index and Abbe number as the material for these lenses. Examples of materials that may be included, but are not limited to, Zeonex® 480R (n=1.525 and V=56.3) and OKP® 4 (nd=1.608 and V=26.9).

[0051] In a further embodiment, in addition to or instead of matching the refractive index and / or Abbe number, the refractive power of one or more lenses 202-210 can be selected to create the optical function of the composite lens 200. Generally, the degree to which light converges or diverges through a lens can be described by its "refractive power". In the case of a single lens, the "refractive power" P is equal to the reciprocal of the focal length f of that lens, so P = 1 / f. The unit of refractive power is therefore m -1 In the case of a system with multiple lenses closely spaced apart, the refractive power of the system is the sum of the refractive powers of the individual lenses P = P1 + P2 + ... + P N This can be approximated by the following: A divergent lens, for example, the negative lens shown in Figure 1A, has a negative refractive power. A converging lens, for example, the positive lens shown in Figure 1B, has a positive refractive power. As an example, "refractive power" can be used to describe the lens's ability to bend light that strikes it; for example, in the case of a divergent lens (e.g., a concave lens), it can bend the light away from the optical axis, and in the case of a converging lens (e.g., a convex lens), it can bend the light toward the optical axis.

[0052] Below, various values ​​are presented regarding the relationship between the refractive powers of lenses 202-210. These values ​​are designed to optimize the imaging function of the composite lens 200, for example, when used in a (small) imaging device. Illustratively, the values ​​discussed below are designed to result in divergence and convergence of combinations that achieve improved final results at the output of the composite lens 200. However, as you can see, in principle, the configuration of lenses 202-210 is not limited to these values. The refractive power ratios described below may be selected by adjusting the refractive power of one or both of the corresponding lenses. The refractive power ratios described below may be provided individually or in combination to suit the overall imaging capability of the composite lens 200.

[0053] In various embodiments, the first refractive power ratio P1 / P2, formed by the first refractive power P1 of the negative first lens 202 relative to the second refractive power P2 of the positive second lens 204, can be set within the range of -1.65 to -1.45, for example, the first refractive power ratio can be set to -1.60. Alternatively, the second refractive power ratio P3 / P2, formed by the third refractive power P3 of the positive third lens 206 relative to the second refractive power P2, can be set within the range of 1.40 to 1.60, for example, the second refractive power ratio can be set to 1.50. Further examples include the third refractive power ratio P3 / P4, formed by the third refractive power P3 of the positive fourth lens 208 relative to the fourth refractive power P4, can be set within the range of 1.90 to 2.15, for example, the third refractive power ratio can be set to 2.00. As a further example, additionally or alternatively, the fourth refractive power ratio P5 / P4, which is the ratio of the fifth refractive power P5 of the negative fifth lens 210 to the fourth refractive power P4 of the positive fourth lens 208, can be set to a range of -1.55 to -1.35, for example, the fourth refractive power ratio can be set to -1.50.

[0054] In a further embodiment, in addition to or by replacing the parameters mentioned above, the configuration of lenses 202-210 can be adapted to result in a low f-number composite lens 200. For example, in the context of wide-field lenses, a lower f-number may allow more light to be captured, and consequently, the corresponding imaging device can operate even in low-light conditions. As an example, since the illumination of a lens system is inversely proportional to the square power of the f-number, a lower f-number of the lens system results in a higher illumination. Generally, the "f-number" of an optical system corresponds to the ratio of the effective focal length to the diameter of the entrance pupil. The f-number can also be called the focal ratio or f-ratio.

[0055] In various configurations, lenses 202-210 can be configured such that the f-number of the composite lens 200 is less than 3.0. For example, the f-number is a primary characteristic of a lens set, defined as the ratio of the aperture diameter to the focal length in the case of infinity conjugate. Therefore, the f-number can be determined and influenced by several of its geometric characteristics, such as the individual lens shapes, materials, axial distances, and vignetting, in addition to the overall configuration of the lens set. Such a low f-number allows for the capture of more signals, thereby increasing the signal-to-noise ratio of the imaging device incorporating the composite lens 200. As an example configuration, in a configuration where the operation of the composite lens has been optimized for integration within a small imaging device (e.g., a small tracking sensor), lenses 202-210 can be configured such that the f-number of the composite lens 200 is in the range of 2.0-2.4, for example, to have an f-number of 2.2.

[0056] The f-number of the composite lens 200 can be adapted, for example, by configuring lenses 202 to 210 such that an effective focal length is obtained that results in an effective focal length with a ratio to the entrance pupil diameter that allows a desired f-number to be obtained. Generally, the effective focal length of the composite lens 200 can be calculated based on the individual focal lengths of lenses 202 to 210 according to equations known in the present art (e.g., assuming that lenses 202 to 210 are thin lenses), or by considering, for example, these individual focal lengths and the lens-to-lens distances between neighboring lenses in the composite lens 200 (e.g., the first distance between the first lens 202 and the second lens 204, the second distance between the second lens 204 and the third lens 206, etc.).

[0057] In various configurations, lenses 202 to 210 can be configured such that the effective focal length of the composite lens 200 is within the range of 0.3 mm to 1.5 mm, for example, such that the effective focal length of the composite lens 200 is 0.76 mm. For example, the individual focal lengths (e.g., the first focal length f1 of the first lens 202, the second focal length f2 of the second lens 204, etc.) and / or the lens-to-lens distance (for example, the center-to-center distance) can be configured such that the effective focal length of the composite lens 200 falls within that range. It has been found that these numerical ranges (and values) provide optimal imaging capabilities suitable for the integration of the composite lens 200 in, for example, a small imaging device. However, as you can see, in principle, the configuration of the composite lens 200 is not limited to these ranges relating to the effective focal length.

[0058] The diameter of the entrance pupil of the composite lens 200 can be defined by the so-called "aperture diaphragm" of the composite lens 200. Generally, in an optical system, the term "aperture diaphragm" can be used to describe a system component that limits the amount of light focused by the optical system. Lenses 202-210 (and corresponding substrates 212-216) can be configured (e.g., designed) such that the aperture diaphragm 222 of the composite lens 200 is located in some preferred position. For example (see also Figure 2B), lenses 202-210 can be configured such that the aperture diaphragm of the composite lens 200 is located between the positive second lens 204 and the positive third lens 206. Exemplarily, the aperture diaphragm 222 can be placed at the interface between the first substrate portion 218a and the second substrate portion 218b of the second substrate 214. Exemplarily, the aperture diaphragm of a system can be understood as a surface whose diameter limits the angular range in which the system can focus light. The aperture diaphragm 222 can therefore be adapted by adapting the dimensions (e.g., diameter) of the positive second lens 204 and the positive third lens 206 and / or the corresponding substrates 214, 218a, 218b.

[0059] Generally, the effective focal length of the composite lens 200 can be adapted, for example, by considering integration with an image sensor, in order to obtain a wide field of view. The composite lens 200 can be configured, for example, by considering the normal dimensions of the image sensor, such as a CMOS image sensor, in order to achieve a wide field of view. The field of view of a system having the composite lens 200 and an image sensor is given by 2tan, where h is the lateral dimension (e.g., horizontal dimension) of the image sensor and F is the (effective) focal length of the composite lens 200. -1 This can be expressed as (h / 2F). Lenses 202-210 can be configured such that the composite lens 200 can achieve an angular field of view within the range of 60°-150°, for example, an angular field of view of 120°. For example, lenses 202-210 can be configured such that the effective focal length of the composite lens 200 is the distance at which an angular field of view within the range of 60°-150° is obtained with a given image sensor (see also Figures 4A-4C).

[0060] In a further embodiment, in addition to or instead of adapting the parameters discussed above, lenses 202-210 can be configured such that a compact module, for example, a compact composite lens 200, is obtained. That is, lenses 202-210 can be arranged relative to each other such that the total track length of the composite lens 200 is shortened. The "total track length" can describe the distance from the top of the composite lens 200 (for example, the top surface of the first substrate 212, which faces the field of view) to the image plane 224 of the composite lens 200 (e.g., the surface of the image sensor). In various embodiments, lenses 202-210 can be configured such that the ratio of the total track length to the effective focal length of the composite lens 200 is in the range of 4.0-5.0. For example, this ratio can be achieved by adapting the individual focal lengths of lenses 202-210 and / or the relative arrangement of lenses 202-210 (lens-to-lens relative distance). The ratio within that range allows for the provision of a compact lens module, thereby facilitating integration within a small imaging device.

[0061] In a further embodiment, in addition to or instead of adapting the parameters discussed above, lenses 202-210 can be configured to provide an image circle diameter suitable for integration within a small imaging device (e.g., within a tracking sensor). The "image circle diameter" can describe the maximum area of ​​the image sensor, i.e., the area that the lens (e.g., composite lens 200) can support without the occurrence of unforeseen effects such as "vignetting." In various embodiments, lenses 202-210 can be configured such that the image circle diameter of composite lens 200 is in the range of 0.5 mm to 3.2 mm, for example, to have an image circle diameter of 1.58 mm. This range (and value) is designed to enable integration with conventional image sensors. However, as you can see, in principle, the configuration of composite lens 200 is not limited to these image circle diameters.

[0062] Further embodiments of the composite lens 200 are illustrated and described below in relation to Figures 3A to 3G. Illustratively, Figures 3A to 3G relate to further features and adaptations that can be introduced into the composite lens 200. The various features and adaptations described in relation to Figures 3A to 3G can be implemented individually or in combination to create a specific embodiment of the composite lens 200.

[0063] In the first configuration 300a, as shown in Figure 3A, the composite lens 200 may have one or more spacers 302, 304 disposed between substrates on which individual lenses are arranged on the surface. For example, the composite lens 200 may have a first spacer 302 disposed between the first substrate 212 and the second substrate 214 (e.g., between the first substrate 212 and the first substrate portion 218a). As a further example, the composite lens 200 may have a second spacer 304 disposed between the second substrate 214 and the third substrate 216 (e.g., between the second substrate portion 218b and the third substrate 216).

[0064] Spacers 302 and 304 can provide structural support to the composite lens 200. Furthermore, the dimensions (e.g., height) of spacers 302 and 304 can be selected to facilitate the adaptation of several characteristics of the composite lens 200, such as the lens-to-lens distance and thus the effective focal length of the composite lens 200. For example, the spacer aperture diameter 306 and / or thickness 308 (e.g., side wall thickness) can be adapted according to desired characteristics of the composite lens 200. Spacers 302 and 304 can contain or be made of some suitable material, such as polymer or glass. For example, glass material can provide a lens stack with more robust mechanical and thermal stability.

[0065] In the second configuration 300b, as shown in Figure 3B, the composite lens 200 may be additionally or alternatively provided with a coating layer 310. The coating layer 310 can provide protection to the composite lens 200 from external factors such as water and dust. In various embodiments, the coating layer 310 may be an anti-reflective coating layer. For example, the coating layer 310 may be configured to reduce the reflection of light entering the composite lens 200. This can improve the focusing of light through the composite lens 200, for example, by reducing the amount of light that is reflected and moves away. As an example, the coating layer 310 may be a dielectric thin film configured to reduce the reflectivity of the composite lens 200.

[0066] The coating layer 310 can be positioned facing the field of view of the composite lens 200. The coating layer 310 can be positioned on the (first) substrate 212 on which the negative first lens 202 is positioned. As shown in Figure 3B, the coating layer 310 can be positioned on the first surface of the substrate 212, and the negative first lens 202 can be positioned on the second surface opposite to the first surface (in the direction along the optical axis of the composite lens 200). By configuring the coating layer 310 in this way to reduce the reflectivity of the (first) surface of the first substrate 212, the focusing of light in the composite lens 200 can be improved.

[0067] In the third configuration 300c, as shown in Figure 3C, the composite lens 200 may have a further optical element 312 disposed on the first substrate 212 (specifically on its first surface) instead of the coating layer 310. For example, the composite lens 200 may have a sixth wafer-level lens 312 disposed on the first substrate 212. This sixth lens 312 can be coaxially aligned with the five lenses 202 to 210. In general, the sixth lens 312 can have any preferred configuration depending on the desired adaptation of the imaging function of the composite lens 200. For example, the sixth lens 312 may be configured as a further plano-convex lens, for example, lens 100b in Figure 1B. Alternatively, the sixth lens 312 may be configured as a further plano-concave lens, for example, lens 100a in Figure 1A. The sixth lens 312 can be provided and configured to adapt one or more characteristics of the composite lens 200, such as effective focal length, magnification, and angular field of view. As shown in Figure 3C, the first substrate 212 can be arranged between the negative first lens 202 and the (positive or negative) sixth lens 312.

[0068] In the fourth configuration 300d, as shown in Figure 3D, the composite lens 200 may be additionally or alternatively equipped with a spectral filter 314. The spectral filter 314 may be configured to filter light, for example, to block light having wavelengths outside a predetermined wavelength range. The spectral filter 314 thus enhances the signal-to-noise ratio of imaging performed using the composite lens 200. The spectral filter 314 may be configured to filter light within some preferred wavelength range, depending on the desired application of the composite lens 200 (and the corresponding imaging device). For example, the predetermined wavelength range may be the visible range. Alternatively, the predetermined wavelength range may be the near-infrared range. In one preferred configuration, the predetermined wavelength range may be a portion (only) of the near-infrared range, exemplifying a limited bandwidth portion within the near-infrared range. In that case, the spectral width of the predetermined wavelength range should be adapted according to a desirable balance between the selectivity of the filter and the need to allow sufficient light to reach the image sensor. Numerical examples include setting the spectral width in the predetermined wavelength range to approximately 1000 nm, for example, 500 nm, or for example, 300 nm. In a corresponding manner, an alternative configuration is to configure the spectral filter 314 to transmit light having wavelengths within the predetermined wavelength range; for example, the spectral filter 314 can be configured as a bandpass filter (e.g., a near-infrared bandpass filter).

[0069] The spectral filter 314 can be placed at any preferred location within the composite lens 200. In one preferred configuration, the spectral filter 314 is embedded within the second substrate 214 to provide a robust arrangement and facilitate integration during the manufacturing process. For example, the spectral filter 314 can be placed between the first substrate portion 218a and the second substrate portion 218b of the second substrate 214. For instance, by placing the spectral filter 314 on the substrate portions 218a and 218b prior to stacking, robust integration of the spectral filter 314 within the lens stack can be achieved as a result of the stacking.

[0070] In the fifth configuration 300e, as shown in Figure 3E, the composite lens 200 may additionally or alternatively have one or more anti-reflective feature structures made of nanostructures. For example, at least one of the lenses 202-210 may have a nanostructured surface that provides anti-reflective properties. In the illustrative representation in Figure 3E, the second lens 204 may be provided with a nanostructured surface 316. However, as can be seen, the embodiments discussed in relation to Figure 3E can also be applied in a corresponding manner to configurations in which other lenses 202-210 or more than one other lens 202-210 have a nanostructured surface 316. In certain embodiments, each lens 202-210 may have a nanostructured surface that provides anti-reflective properties. For example, in certain embodiments, each lens 202-210 may have a lens surface with an anti-reflective feature structure made of nanostructures.

[0071] The nanostructured surface 316 can be configured in any suitable manner to provide anti-reflective properties. Generally, the nanostructured surface 316 may have an array of nanostructures, such as nanopillars, nanopyramids, probabilistic cloudlets, spongy nanostructures, and / or similar structures. The nanostructure array forming the nanostructured surface may have a sub-wavelength pitch, for example, a sub-wavelength inter-neighboring-center-to-center distance. The design of the nanostructured surface can thus be adapted according to the intended application of the composite lens 200, for example, for imaging in the visible or near-infrared region. The pitch may be smaller than the shortest wavelength within a predetermined wavelength range related to the operation of the composite lens. As an example of numerical values, the pitch of the nanostructure array may be in the range of 50 nm to 500 nm, for example, in the range of 100 nm to 300 nm.

[0072] These nanostructures may exhibit sub-wavelength lateral dimensions (e.g., width) in the plane, or, more precisely, dimensions perpendicular to the height of the nanostructure may be sub-wavelength. As a numerical example, the height of these nanostructures can be within the range of 50 nm to 2000 nm, for example, 100 nm to 1000 nm. As a further numerical example, the lateral dimensions of these nanostructures can be within the range of 10 nm to 500 nm, for example, 50 nm to 100 nm.

[0073] In the sixth configuration 300f, as shown in Figure 3F, the composite lens 200 may additionally or alternatively be provided with one or more clear optical apertures 318, 320, 322, and 324 along the optical path (exemplarily along its optical axis). The optical apertures 318 to 324 can suppress stray light, thereby contributing to an improvement in the signal-to-noise ratio of the imaging process performed with the composite lens 200. The clear optical apertures 318, 320, 322, and 324 may have one or more light-shielding portions that define the contours of the clear optical apertures 318, 320, 322, and 324.

[0074] As an example, the composite lens 200 may be equipped with a first clear optical aperture 318, and its location may be on the first substrate 212, for example, on the first surface opposite to the surface on which the negative first lens 210 is disposed. As an alternative example, the composite lens 200 may be additionally or alternatively equipped with a second clear optical aperture 320, and its location may be on the first substrate 212, for example, on the same surface on which the negative first lens 210 is disposed.

[0075] As a further example, the composite lens 200 may additionally or alternatively include a third clear optical aperture 322, and its location may be between the positive second lens 204 and the positive third lens 206. For example, the third clear optical aperture 322 may be incorporated into the second substrate 214 and located, for example, between the first substrate portion 218a and the second substrate portion 218b. As a further example, the composite lens 200 may additionally or alternatively include a fourth optical aperture 324, and its location may be on the third substrate 216, for example, on the same surface on which the positive fourth lens 208 is located (as shown in Figure 3F), or on the same surface on which the negative fifth lens 210 is located.

[0076] Figure 3G shows the seventh component 300g of the composite lens 200, which incorporates the features discussed in relation to Figures 3A to 3F, such as spacers 302 and 304, an anti-reflective coating 310, a spectral filter 314, and optical apertures 318 to 324. In certain embodiments, the seventh component 300g may further have nanostructures on the surface of one or more lenses (e.g., each) of the lenses 202 to 210.

[0077] Figures 4A, 4B, and 4C show imaging devices 400a, 400b, and 400c having wafer-level composite lenses and image sensors configured as described in this application according to various embodiments. Imaging devices 400a, 400b, and 400c can be configured for any suitable application. In one preferred configuration, imaging devices 400a, 400b, and 400c are incorporated into a tracking sensor. The representation of imaging devices 400a, 400b, and 400c is simplified for illustrative purposes, and additional components, such as one or more filters, one or more amplifiers, one or more processors, etc., may be incorporated into imaging devices 400a, 400b, and 400c in addition to those shown. In general, the wafer-level composite lens 200 incorporated into imaging devices 400a, 400b, and 400c may be configured according to any of the configurations discussed in relation to Figures 2A to 3G. For illustrative purposes, Figures 4A and 4B show a composite lens 200 having the configuration shown in Figure 2A. As you can see, the composite lens 200 may have any of the features discussed in relation to Figures 3A to 3G.

[0078] The imaging devices 400a, 400b, and 400c can be equipped with an image sensor 402. The image sensor 402 can be configured to be sensitive to light within a predetermined wavelength range, for example, within the visible or near-infrared range. For example, the image sensor 402 can be configured to convert the optical energy (e.g., photons) of light striking the image sensor 402 into electrical energy (e.g., electric current, e.g., photocurrent). Generally, the imaging devices 400a, 400b, and 400c can have compact dimensions, for example, a small footprint. For example, the image sensor 402 can be a chip-scale packaged image sensor.

[0079] The geometry (e.g., shape and lateral dimension) of the image sensor 402 can be adapted according to system requirements, for example, according to the overall dimensions of the imaging devices 400a, 400b, 400c, or according to manufacturing constraints, etc. The image sensor 402 can thus have any suitable shape, for example, rectangular, square, or even an asymmetric shape. Generally, the image sensor 402 has a plurality of pixels, for example, a first plurality of pixels N x where the first dimension is defined and a second plurality of pixels N y where the second dimension is defined. In various embodiments, the image sensor may be considered to have a two-dimensional pixel array. The number of pixels N x , N y in each direction, as well as the pixel pitch, can be adapted according to the desired dimensions of the image sensor 402. As numerical examples, the image sensor 402 can be made to have at least 10 4 pixels (e.g., 100×100 pixels), for example, at least 4×10 4 pixels (e.g., 200×200 pixels). As another numerical example, the image sensor 402 can be made to have a lateral dimension (e.g., width) within the range of 1 mm to 10 mm, for example, within the range of 2 mm to 5 mm.

[0080] According to various embodiments, the image sensor 402 can be configured according to complementary metal-oxide semiconductor (CMOS) technology, for example, the image sensor 402 can be a CMOS image sensor. In this configuration, the image sensor 402 can have a plurality of CMOS pixels each having a photodetector, and charges corresponding to the amount of light incident on the photodetector are accumulated in the photodetector. As another example configuration, the image sensor 402 can be configured according to charge-coupled device (CCD) technology, for example, the image sensor 402 can be a CCD image sensor. In this configuration, the image sensor 402 can have a plurality of CCD pixels with light-active regions and transmission regions.

[0081] In imaging devices 400a, 400b, and 400c, the field of view of the image sensor 402 can be defined by the wafer-level composite lens 200. For example, the composite lens 200 can be configured to collect light and direct the collected light onto the image sensor 402, for example, onto one or more pixels of the image sensor 402 (e.g., to focus). The composite lens 200 with the configuration proposed here will certainly have a wide angular field of view for the imaging device, as well as high spatial resolution and high contrast, as discussed earlier. The image sensor 402 can be positioned within the image plane of the composite lens 200. For example, as shown in Figures 4A to 4C, the composite lens 200 can be positioned so that the negative fifth lens 210 faces the image sensor 402.

[0082] In various configurations, as shown in Figure 4A, the composite lens 200 can be directly coupled to the image sensor 402, for example, to the substrate of the image sensor 402. This configuration offers a simpler manufacturing process and allows the composite lens 200 to be in direct physical contact with the substrate of the image sensor 402. In one configuration example, the composite lens 200 may have a (fourth) spacer 404 disposed between the third substrate 216 and the image sensor 402 (exemplarily between the third substrate 216 and the substrate of the image sensor 402). The (fourth) spacer 404 can provide structural support to the composite lens 200 and can be adapted to define the distance between the composite lens 200 and the image sensor 402.

[0083] In other embodiments, as shown in Figure 4B, the image sensor 402 may have a cover glass 406 that enhances the protection of the image sensor 402. The cover glass 406 can be placed on the substrate of the image sensor 402 to cover it. In this configuration, the composite lens 200 can be coupled with the cover glass 406, for example, by placing a (fourth) spacer 404 between the third substrate 216 and the cover glass 406 of the image sensor 402. Exemplarily, the composite lens 200 can be mechanically integrated with the cover glass 406 of the image sensor 402.

[0084] In the imaging device 400c with the configuration shown in Figure 4C, the composite lens 200 has the features discussed in relation to Figures 3A to 3F, such as spacers 302 and 304, an anti-reflective coating 310, a spectral filter 314, and optical apertures 318 to 324. In certain embodiments, the composite lens 200 may further have nanostructures on the surface of one or more of the lenses 202 to 210 (e.g., each of them). In various embodiments, the image sensor 402 may be provided with a back-side conductive contact pad 408 (and corresponding solder balls) to enable electrical coupling with another circuit, such as a host device.

[0085] Figures 5A to 5E show various graphs 500a, 500b, 500c, 500d, and 500e illustrating various characteristics of a wafer-level composite lens configured as described in this application. As you can see, the purpose of graphs 500a, 500b, 500c, 500d, and 500e is to illustrate the promising characteristics and parameters that can be achieved with the configuration proposed in this application, and there is no intention to limit the overall configuration of the composite lens.

[0086] Graph 500a in Figure 5A shows the white light modulation transfer function of a wafer-level composite lens configured as described in this application. In graph 500a, the Y field of view is shown in millimeters along the x axis, and the coefficients of the optical transfer function (OTF) are shown along the y axis. Graph 500a shows the modulus transfer function at two different frequencies: the first curve 502 is the modulus transfer function at 45.00 cycles / mm, and the second curve 504 is the modulus transfer function at 90.00 cycles / mm. As indicated by the large modulus transfer function values ​​and the flatness of curves 502 and 504, the optical performance is improved, and in particular, the image contrast achievable by the wafer-level composite lens is increased.

[0087] In Graph 500b in Figure 5B, the optical transfer function coefficients are shown along the y-axis, and the corresponding focal shift is shown along the x-axis (in millimeters). Illustratively, Graph 500b can represent the through-focus modulus transfer function of a wafer-level composite lens. As shown by the curves plotted in Graph 500b (both sagittal and tangential), the contrast and robustness achievable with a wafer-level composite lens are improved. Plot 500b was obtained through simulations in the spectral bandwidth of 420 nm to 750 nm. The following curves are shown in Graph 500b, and they relate to different field-of-view angular coordinates. Solid lines relate to the tangential plane, and dashed lines relate to the sagittal plane. The first curve 526 relates to 0.0000 mm tangential. The second curve 528 relates to 0.4990 mm tangential. The third curve 530 relates to 0.7057 mm tangential. Curve 4, 532, relates to 0.0000 mm sagittal. Curve 5, 534, relates to 0.4990 mm sagittal. Curve 6, 536, relates to 0.7057 mm sagittal. Curve 7, 538, relates to 0.3529 mm tangential. Curve 8, 540, relates to 0.6112 mm tangential. Curve 9, 542, relates to 0.7890 mm tangential. Curve 10, 544, relates to 0.3529 mm sagittal. Curve 11, 546, relates to 0.6112 mm sagittal. Curve 12, 548, relates to 0.7890 mm sagittal.

[0088] Graph 500c in Figure 5C shows the monotonic distortion curve of a wafer-level composite lens. As the curve in this graph shows, this wafer-level composite lens can achieve strong negative f-tan (theta) distortion (specifically barrel distortion) as expected from a wide-field lens. These characteristics can improve image data evaluation and resolution in feature tracking applications.

[0089] In Graph 500d in Figure 5D, the field-view real image height at various wavelengths is shown along the y-axis (in millimeters). Specifically, the first curve 516 represents the field-view real image height at 440 nm, the second curve 518 at 470 nm, the third curve 520 at 510 nm, the fourth curve 522 at 555 nm, and the fifth curve 524 at 650 nm. As shown in Graph 500c, the wafer-level composite lens can achieve low lateral chromatic aberration, and therefore can be optimized to achieve good decolorization.

[0090] In Graph 500e in Figure 5E, relative illumination is shown along the y-axis, and the corresponding Y-field of view is shown along the x-axis (in millimeters). As illustrated, this wafer-level composite lens can achieve high off-axis relative illumination, which in turn can provide a high signal-to-noise ratio for imaging applications.

[0091] The following presents various examples of wafer-level composite lenses 200.

[0092] Example 1 is a wafer-level composite lens comprising five coaxially aligned lenses, each containing a negative first lens, a positive second lens, a positive third lens, a positive fourth lens, and a negative fifth lens in that order; a (second) substrate disposed between the positive second lens and the positive third lens; and a further (third) substrate disposed between the positive fourth lens and the negative fifth lens.

[0093] In Example 2, the wafer-level composite lens according to Example 1 can optionally be further configured such that the negative first lens faces the positive second lens, and the positive third lens faces the positive fourth lens.

[0094] In Example 3, the wafer-level composite lens according to Example 1 or 2 may optionally be further provided with a (second) spacer disposed between the (second) substrate and the (third) substrate.

[0095] In Example 4, the wafer-level composite lens relating to any one of Examples 1 to 3 can optionally have an additional (first) substrate on which a negative first lens is disposed.

[0096] In Example 5, the wafer-level composite lens according to Example 4 may optionally have an additional coating layer disposed on the (first) substrate, wherein the negative first lens is disposed on the first surface of the (first) substrate and the coating layer is disposed on the second surface of the (first) substrate, and the first surface of the wafer-level composite lens is on the opposite side of the second surface in the direction along the optical axis of the wafer-level composite lens.

[0097] In Example 6, the wafer-level composite lens according to Example 5 can optionally be further modified so that its coating layer is an anti-reflective coating layer.

[0098] In Example 7, the wafer-level composite lens according to Example 4 can optionally have a sixth lens coaxially aligned with the five coaxially aligned lenses, and the (first) substrate can be disposed between the negative first lens and the sixth lens.

[0099] In Example 8, the wafer-level composite lens according to any one of Examples 4 to 7 may optionally further have a (first) spacer disposed between the other (first) substrate and the (second) substrate.

[0100] In Example 9, the wafer-level composite lens according to any one of Examples 1 to 8 can optionally be further modified such that the (second) substrate has a first substrate portion integrally bonded (e.g., stacked) with the second substrate portion, a positive second lens is disposed on the first surface of the first substrate portion, and a positive third lens is disposed on the second surface of the second substrate portion, and in the direction along the optical axis of the wafer-level composite lens, the second surface of the second substrate portion is on the opposite side from the first surface of the first substrate portion.

[0101] In Example 10, the wafer-level composite lens according to Example 9 can optionally be further equipped with a spectral filter disposed between the first substrate portion and the second substrate portion, wherein the spectral filter is configured to block light having wavelengths outside a predetermined wavelength range.

[0102] In Example 11, the wafer-level composite lens according to Example 10 can optionally be further configured such that the predetermined wavelength range is in the visible range, or the predetermined wavelength range is in the near-infrared range. For example, the predetermined wavelength range can be a sub-region within the near-infrared range.

[0103] In Example 12, the wafer-level composite lens according to any one of Examples 1 to 11 can optionally be further configured such that the negative first lens contains or is composed of a first material having a first refractive index and a first Abbe number, and the positive second lens contains or is composed of a second material having a second refractive index and a second Abbe number, wherein the second refractive index is higher than the first refractive index and the first Abbe number is greater than the second Abbe number.

[0104] In Example 13, the wafer-level composite lens according to Example 12 can optionally be further configured such that the positive third lens contains or is composed of a third material having a third refractive index and a third Abbe number, and the positive fourth lens contains or is composed of a fourth material having a fourth refractive index and a fourth Abbe number, wherein the third and fourth refractive indices are equal to the first refractive index and the third and fourth Abbe numbers are equal to the first Abbe number.

[0105] In Example 14, the wafer-level composite lens according to Example 12 or 13 can optionally be further configured such that the negative fifth lens contains or is composed of a fifth material having a fifth refractive index and a fifth Abbe number, wherein the fifth refractive index is higher than the first refractive index and the first Abbe number is greater than the fifth Abbe number.

[0106] In Example 15, the wafer-level composite lens relating to any one of Examples 1 to 14 can optionally be further configured such that the first refractive power ratio between the first refractive power of the negative first lens and the second refractive power of the positive second lens is within the range of -1.65 to -1.45. For example, the first refractive power ratio can be set to -1.60.

[0107] In Example 16, the wafer-level composite lens relating to any one of Examples 1 to 15 can optionally be further configured such that the second refractive power ratio between the third refractive power of the positive third lens and the second refractive power of the positive second lens is within the range of 1.40 to 1.60. For example, the second refractive power ratio can be set to 1.50.

[0108] In Example 17, the wafer-level composite lens relating to any one of Examples 1 to 16 can optionally be further modified so that the ratio of the third refractive power between the third refractive power of the positive third lens and the fourth refractive power of the positive fourth lens is within the range of 1.90 to 2.15. For example, the ratio of the third refractive power can be set to 2.00.

[0109] In Example 18, the wafer-level composite lens relating to any one of Examples 1 to 17 can optionally be further configured such that the fourth refractive power ratio between the fifth refractive power of the negative fifth lens and the fourth refractive power of the positive fourth lens is within the range of -1.55 to -1.35. For example, the fourth refractive power ratio can be set to -1.50.

[0110] In Example 19, the wafer-level composite lens according to any one of Examples 1 to 18 can optionally be further modified to have an anti-reflective feature structure made of nanostructures, such as a nanostructure array having a subwavelength pitch, on the surface of at least one of the negative first lens, positive second lens, positive third lens, positive fourth lens, and negative fifth lens.

[0111] In Example 20, a wafer-level composite lens relating to any one of Examples 1 to 19 can optionally be further modified to have individual anti-reflective feature structures created with nanostructures, such as nanostructure arrays having sub-wavelength pitches, on the individual lens surfaces of each of the negative first lens, positive second lens, positive third lens, positive fourth lens, and negative fifth lens.

[0112] In Example 21, the wafer-level composite lens according to any one of Examples 1 to 20 can optionally be configured such that the f-number of the wafer-level composite lens is less than 3.0, with the five coaxially aligned lenses configured accordingly. For example, the five coaxially aligned lenses can be configured such that the f-number of the wafer-level composite lens is in the range of 2.0 to 2.4. Alternatively, the five coaxially aligned lenses can be configured such that the f-number of the wafer-level composite lens is 2.2.

[0113] In Example 22, the wafer-level composite lens according to any one of Examples 1 to 21 can be optionally configured with five coaxially aligned lenses so that the angular field of view of the wafer-level composite lens is within the range of 60° to 150°. For example, the five coaxially aligned lenses can be configured so that the angular field of view of the wafer-level composite lens is 120°.

[0114] In Example 23, the wafer-level composite lens according to any one of Examples 1 to 22 can be optionally configured with five coaxially aligned lenses such that the effective focal length of the wafer-level composite lens is in the range of 0.3 mm to 1.5 mm. For example, the five coaxially aligned lenses can be configured such that the effective focal length of the wafer-level composite lens is 0.76 mm.

[0115] In Example 24, the wafer-level composite lens according to any one of Examples 1 to 23 can optionally be further configured such that the ratio of the total track length to the effective focal length of the wafer-level composite lens is in the range of 4.0 to 5.0, with the five coaxially aligned lenses being configured accordingly.

[0116] In Example 25, the wafer-level composite lens according to any one of Examples 1 to 24 can be optionally further configured with five coaxially aligned lenses such that the image circle diameter of the wafer-level composite lens is within the range of 0.5 mm to 3.2 mm. For example, the five coaxially aligned lenses can be configured such that the image circle diameter of the wafer-level composite lens is 1.58 mm.

[0117] In Example 26, the wafer-level composite lens according to any one of Examples 1-6 and 8-25 can optionally be further configured as a wafer-level composite lens composed of the five coaxially aligned lenses.

[0118] In Example 27, the wafer-level composite lens relating to any one of Examples 1 to 26 can optionally be further modified by making the (second) substrate a glass wafer or having one, and / or making the further (third) substrate a glass wafer or having one.

[0119] In Example 28, the wafer-level composite lens relating to any one of Examples 1 to 27 may optionally further include a (third) clear optical aperture between the positive second lens and the positive third lens, and a (fourth) clear optical aperture between the positive fourth lens and the negative fifth lens.

[0120] In Example 29, the wafer-level composite lens according to Example 28 may optionally be further provided with a (first) clear optical aperture disposed between the negative first lens and the object surface of the wafer-level composite lens.

[0121] Example 30 is an imaging device comprising an image sensor and a wafer-level composite lens relating to any one of Examples 1 to 29, wherein the field of view of the image sensor is defined by the wafer-level composite lens.

[0122] In Example 31, the imaging device according to Example 30 can optionally be further equipped with a wafer-level composite lens such that the negative fifth lens faces the image sensor.

[0123] In Example 32, the imaging device according to Example 30 or 31 can optionally be further configured such that the image sensor is sensitive to light having wavelengths in the visible range, or so that the image sensor is sensitive to light having wavelengths in the near-infrared range.

[0124] In Example 33, the imaging device relating to any one of Examples 30 to 32 can optionally be further modified to include an image sensor with a chip-scale packaged image sensor.

[0125] In Example 34, the imaging device relating to any one of Examples 30 to 33 can optionally be further modified to include a wafer-level composite lens directly coupled to the image sensor substrate.

[0126] In Example 35, the imaging device according to Example 34 may optionally further include a wafer-level composite lens further comprising a (third) spacer disposed between the further (third) substrate and the image sensor substrate.

[0127] In Example 36, the imaging device according to any one of Examples 30 to 33 can optionally be further configured such that the image sensor further has a cover glass disposed on the substrate of the image sensor, and a wafer-level composite lens is coupled to the cover glass of the image sensor.

[0128] In Example 37, the imaging device according to Example 36 may optionally further include a wafer-level composite lens, which further comprises a (third) spacer disposed between the further (third) substrate and the cover glass of the image sensor.

[0129] Example 38 is a tracking sensor device having an imaging device relating to any one of Examples 30 to 37.

[0130] In this application, the term "exemplary" is used in the sense of "serving as an example, case, or illustration." Not all embodiments or designs described in this application as "exemplary" are necessarily considered to be preferable or advantageous to other embodiments or designs.

[0131] The phrases "at least one" and "one or more" can be understood to include a quantity of one or more (e.g., 1, 2, 3, 4, ...). The phrase "at least one of" relating to a group of elements, according to its usage in this application, would mean at least one element within the group of elements composed of those elements. For example, the phrase "at least one of" relating to a group of elements, according to its usage in this application, would mean the selection of one element from the listed elements, multiple selections of one element from the listed elements, the selection of multiple individual elements from the listed elements, or multiple selections of multiple individual elements from the listed elements.

[0132] All acronyms defined in the above description are, additionally, valid in all claims provided in this application.

[0133] While the present invention has been specifically illustrated and described with reference to various embodiments, it should be understood by those skilled in the art that various modifications can be made to the form and details without deviating from the technical scope of the present invention as defined by the appended claims. In other words, the technical scope of the present invention is indicated by the appended claims, and therefore, all modifications that fall within the semantic scope or equivalent scope of the claims are implicitly included. [Explanation of Symbols]

[0134] 102a Wafer-level lens, 102b Wafer-level lens, 104a substrate, 104b substrate, 106a flat surface, 106b flat surface, 108a concave, 108b convex, 110a focal length, 110b focal length, 112a focus, 112b focus, 200 wafer-level composite lenses, 202 First wafer level lens, 204 Second wafer level lens, 206 Third wafer level lens, 208 Fourth wafer level lens, 210 Fifth wafer level lens, 212 First board, 214 Second board, 216 Third board, 218a board part, 218b board part, 220 optical axis, 222 Aperture diaphragm, 224 image plane, 300a 1st configuration, 300b second configuration, 300c third configuration, 300d 4th configuration, 300e 5th configuration, 300f 6th configuration, 300g 7th configuration, 302 First spacer, 304 Second spacer, 306 Spacer opening diameter, 308 thickness, 310 coating layer, 312 Sixth lens, 314 Spectroscopic filters, 316 nanostructured surfaces, 318 first optical aperture, 320 second optical aperture, 322 third optical aperture, 324 fourth optical aperture, 400a imaging device, 400b imaging device, 400c imaging device, 402 Image sensor, 404 Spacer, 406 Cover glass, 408 Contact pads, 500a graph, 500b graph, 500c graph, 500d graph, 500e graph, 500f graph, 500g graph, 502 first curve, 504 second curve, 506 first curve, 508 second curve, 510 third curve, 512 4th curve, 514 5th curve, 516 first curve, 518 second curve, 520 third curve, 522 4th curve, 524 5th curve, 526 first curve, 528 second curve, 530 third curve, 532 4th curve, 534 5th curve, 536 6th curve, 538 7th curve, 540 8th curve, 542 9th curve, 544 10th curve, 546 11th curve, 548 Curve 12.

Claims

1. A wafer-level composite lens (200), Equipped with five coaxially aligned wafer-level lenses, The five coaxially aligned wafer-level lenses include, in order, a negative first lens (202), a positive second lens (204), a positive third lens (206), a positive fourth lens (208), and a negative fifth lens (210). The substrate (214) is disposed between the positive second lens (204) and the positive third lens (206), A wafer-level composite lens comprising a further substrate (216) disposed between the positive fourth lens (208) and the negative fifth lens (210).

2. A wafer-level composite lens (200) according to claim 1, further, Another circuit board (212), A coating layer (310) disposed on the aforementioned other substrate (212), Equipped with, The coating layer (310) is disposed on the first surface of the other substrate (212), The negative first lens (210) is disposed on the second surface of the other substrate (212), and A wafer-level composite lens (200) in which the first surface is on the opposite side of the second surface in a direction along the optical axis (220) of the wafer-level composite lens (200).

3. A wafer-level composite lens (200) according to claim 1 or 2, The substrate (214) comprises a first substrate portion (218a) integrally bonded with a second substrate portion (218b), The positive second lens (204) is disposed on the first surface of the first substrate portion (218a), and A wafer-level composite lens in which the positive third lens (206) is disposed on the second surface of the second substrate portion (218b), and the second surface of the second substrate portion is on the opposite side of the first surface of the first substrate portion in the direction along the optical axis (220) of the wafer-level composite lens (200).

4. A wafer-level composite lens (200) according to claim 3, further, The device includes a spectral filter (314) disposed between the first substrate portion (218a) and the second substrate portion (218b), The spectral filter (314) is configured to block light having wavelengths outside a predetermined wavelength range.

5. A wafer-level composite lens (200) according to claim 3 or 4, A wafer-level composite lens in which the coaxially aligned wafer-level lenses (202, 204, 206, 208, 210) are configured such that an aperture diaphragm (222) disposed between the first substrate portion (218a) and the second substrate portion (218b) is provided on the wafer-level composite lens (200).

6. A wafer-level composite lens (200) according to any one of claims 1 to 5, The negative first lens (202) contains or is composed of a first material having a first refractive index and a first Abbe number. The positive second lens (204) contains or is composed of a second material having a second refractive index and a second Abbe number. A wafer-level composite lens in which the second refractive index is higher than the first refractive index and the first Abbe number is greater than the second Abbe number.

7. A wafer-level composite lens (200) according to claim 6, The positive third lens (206) contains or is composed of a third material having a third refractive index and a third Abbe number. The positive fourth lens (208) contains or is composed of a fourth material having a fourth refractive index and a fourth Abbe number, and A wafer-level composite lens in which the third refractive index and the fourth refractive index are equal to the first refractive index and the third Abbe number and the fourth Abbe number are equal to the first Abbe number.

8. A wafer-level composite lens (200) according to claim 6 or 7, The negative fifth lens (210) contains or is composed of a fifth material having a fifth refractive index and a fifth Abbe number, and A wafer-level composite lens in which the fifth refractive index is higher than the first refractive index and the first Abbe number is greater than the fifth Abbe number.

9. A wafer-level composite lens (200) according to any one of claims 1 to 8, The first refractive power ratio between the first refractive power of the negative first lens (202) and the second refractive power of the positive second lens (204) is in the range of -1.65 to -1.45, and / or The ratio of the second refractive power between the third refractive power of the positive third lens (206) and the second refractive power of the positive second lens (204) is in the range of 1.40 to 1.60, and / or The ratio of the third refractive power between the third refractive power of the positive third lens (206) and the fourth refractive power of the positive fourth lens (208) is in the range of 1.90 to 2.15, and / or A wafer-level composite lens in which the fourth refractive power ratio between the fifth refractive power of the negative fifth lens (210) and the fourth refractive power of the positive fourth lens (208) is in the range of -1.55 to -1.

35.

10. A wafer-level composite lens (200) according to any one of claims 1 to 9, A wafer-level composite lens having an anti-reflective feature structure made of nanostructure on the surface of at least one of the negative first lens (202), the positive second lens (204), the positive third lens (206), the positive fourth lens (208), and / or the negative fifth lens (210).

11. A wafer-level composite lens (200) according to any one of claims 1 to 10, A wafer-level composite lens in which the coaxially aligned wafer-level lenses (202, 204, 206, 208, 210) are configured such that the f-number of the wafer-level composite lens (200) is less than 3.

0.

12. A wafer-level composite lens (200) according to any one of claims 1 to 11, A wafer-level composite lens in which the coaxially aligned wafer-level lenses (202, 204, 206, 208, 210) are configured such that the ratio of the total track length to the effective focal length of the wafer-level composite lens (200) is in the range of 4.0 to 5.

0.

13. A wafer-level composite lens (200) according to any one of claims 1 to 12, A wafer-level composite lens (200) is composed of the aforementioned coaxially aligned wafer-level lenses (202, 204, 206, 208, 210).

14. Imaging devices (400a, 400b, 400c), Image sensor (402), A wafer-level composite lens (200) according to any one of claims 1 to 13, An imaging device comprising the wafer-level composite lens (200) wherein the field of view of the image sensor (402) is defined by the wafer-level composite lens (200).

15. The imaging device (400a, 400b, 400c) according to claim 14, The wafer-level composite lens (200) is directly coupled to the substrate of the image sensor (402), or The image sensor (402) further comprises a cover glass (406) disposed on the substrate of the image sensor (402), and the wafer-level composite lens (200) is coupled to the cover glass (406) of the image sensor (402). Imaging device.

Images