System and method for aligning multiple lens elements

Abstract

In aligning lens elements of a lens assembly, the lens assembly is separated into a first lens module including at least one lens element and a second lens module including at least one additional lens element. A coarse alignment is performed by aligning an optical axis of at least one lens element in the first lens module with an optical axis of at least one lens element in the second lens module. For fine alignment, a test chart is viewed through the image sensor when the first lens module and the second lens module are located between the test chart and the image sensor. An image quality index is obtained from the image sensor of the test chart at different relative alignments between the first lens module and the second lens module; then, the first lens module is fixed to the second lens module at a relative alignment between the first lens module and the second lens module that optimizes the image quality index.

Description

Technical Field

[0001] The present invention relates to aligning multiple lens elements of a lens assembly when the lens assembly is coupled to an image sensor to obtain optimized image quality in an optical system. Background Art

[0002] In the assembly of an optical system for a camera module, such as in a smartphone and a portable personal device, the optical performance or imaging quality of the camera module depends largely on whether its optical elements can be accurately aligned. The alignment includes the alignment between the lens assembly and the image sensor chip, and the accurate alignment between the lens elements included in the lens assembly.

[0003] In the alignment process of the above optical elements, the camera module active alignment (AA) process is used to optimally align the lens assembly with the image sensor chip. In this process, the image sensor is powered to capture an image in a test chart through the lens assembly, as described in the invention of U.S. Patent No. 9,009,952, "Apparatus for assembling a lens module and an image sensor to form a camera module and an assembly method thereof". In order to produce a camera module with optimized image quality obtained at least in the center and peripheral areas of the image sensor, a six-axis motion system can be used to hold the lens assembly or the image sensor chip to ensure that the image sensor chip is accurately aligned with the imaging plane of the lens assembly.

[0004] In addition, in order to avoid the degradation of image quality caused by the lens assembly itself, each lens element needs to be accurately designed and manufactured, and the assembly tolerance of each lens element needs to be precisely controlled. In conventional lens assemblies, the individual lens elements included in the lens assembly are mounted on the lens frame one by one. In order to firmly fix each lens element during the installation process, different interlocking designs are required to maintain the orientation of the individual lens elements relative to each other. However, when the number of lens elements increases, the requirements for assembly tolerances are more stringent, and the assembly errors in such designs become more difficult to control. At the same time, during the installation and assembly process of conventional lens elements, due to the cumulative assembly errors caused by factors such as installation accuracy and the manufacturing defects caused by the individual lens elements, the optical performance of the lens assembly cannot be managed as a whole. Therefore, when the number of lens elements included in each lens assembly increases, the final yield loss in the production of the lens assembly will also tend to increase.

[0005] Figure 11 is a cross-sectional view of a conventional lens assembly including a plurality of lens elements assembled in an interlocking lens holder 100. During the AA process, the lens elements mounted in the interlocking lens holder 100 are aligned with respect to the functional image sensor 104 located on the sensor board 102. After alignment, ideally, the interlocking lens holder 100 is fixed to the sensor board 102 along an alignment direction, wherein the optical axis of the functional image sensor 104 coincides with the optical axis of the lens assembly to ensure that the functional image sensor 104 is accurately aligned with the imaging plane provided by the plurality of lens elements. However, the plurality of lens elements 106, 108, 110, 112, 114 may respectively include optical axes in different directions, resulting in that the total optical axis 116 of the lens assembly may deviate excessively from the optical axis of the functional image sensor 104, thereby making it difficult or impossible to accurately align the total optical axis 116 of the lens assembly with the optical axis of the functional image sensor 104. To this end, if the total optical axis 116 is pre-aligned with the expected optical axis of the functional image sensor 104, the optical axis of the lens assembly can be more accurately aligned with the optical axis of the functional image sensor 104 to avoid excessive deviation when attempting to secure the interlocking lens holder 100 to the sensor board 102.

[0006] Therefore, it would be beneficial to invent a system and method for aligning multiple lens elements included in a lens assembly to achieve a desired overall optical axis 116 of the lens assembly. This ensures that the functional image sensor 104 is aligned relative to the lens assembly to achieve optimal image quality in the finished product. Summary of the invention

[0007] In view of the above, an object of the present invention is to attempt to provide a method for aligning a plurality of lens elements included in a lens assembly.

[0008] Therefore, the present invention provides a method for aligning multiple lens elements included in a lens assembly, the method comprising the following steps: dividing the lens assembly into a first lens module including at least one lens element and a second lens module including at least one other lens element; performing a rough alignment between the first lens module and the second lens module by aligning the optical axis of at least one lens element included in the first lens module with the optical axis of at least one lens element included in the second lens module; viewing a test chart through an image sensor when the first lens module and the second lens module are located between a test chart and an image sensor; obtaining an image quality index from the image sensor of the test chart at different relative alignments between the first and second lens modules to perform a fine alignment between the first lens module and the second lens module; and then, fixing the first lens module on the second lens module at the relative alignment between the first lens module and the second lens module where the image quality index is optimized.

[0009] The invention is described in more detail below with reference to the accompanying drawings showing specific preferred embodiments of the invention. The particularity of the drawings and the related description should not be understood as superseding the generality of the broadly defined invention as defined by the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] An exemplary process for aligning lens elements provided by the present invention will now be described with reference to the accompanying drawings.

[0011] Figure 1 is a cross-sectional view of a conventional lens assembly including multiple lens elements assembled in an interlocking lens holder.

[0012] Figure 2 is a cross-sectional view of a lens assembly according to a preferred embodiment of the present invention, wherein one lens element of the lens assembly is removed from the interlocking lens holder to perform an alignment process.

[0013] Figure 3A is an isometric view of an optical detector for measuring a spherical surface of at least one lens element included in an interlocking lens holder; Figure 3B Isometric view of an optical detector used to measure the spherical surface of a separate lens element.

[0014] Figure 4A shows the measured spherical profile of a lens element included in an interlocking lens holder; Figure 4B The measured spherical profile of the separate lens element is shown.

[0015] Figure 5 A layout of a lens alignment apparatus that can be used to perform an alignment process according to a preferred embodiment of the present invention is shown.

[0016] Figure 6 is a flow chart of an exemplary alignment process.

[0017] Figure 7 An adhesive dispenser is shown dispensing adhesive onto an interlocking lens holder.

[0018] Figure 8 The separate lens element is shown secured to the interlocking lens holder in an aligned position. DETAILED DESCRIPTION

[0019] Figure 2FIG. 1 is a cross-sectional view of a lens assembly according to a preferred embodiment of the present invention, wherein one lens element in the lens assembly is removed from the interlocking lens holder 10 to implement the alignment process. In the illustrated embodiment, the entire lens assembly includes five lens elements 16, 18, 20, 22, 24. Four of the five lens elements 16, 18, 20, 22 are assembled in the interlocking lens holder 10, wherein the interlocking lens holder 10 is used to be fixed on a sensor board having the functional image sensor 104 after the functional image sensor 104 is aligned with the combined lens elements 16, 18, 20, 22 in the lens assembly.

[0020] like Figure 2 As shown, in this embodiment, one of the lens elements 24 included in the lens assembly is separated from the interlocking lens holder 10 and assembled on a separate separate lens holder 26 to form a separate lens module. This allows the separate lens element 24 to be pre-aligned relative to the plurality of other lens elements 16, 18, 20, 22 in another lens module, so that the overall optical axis 28 of the lens assembly is pre-aligned as closely as possible with the intended optical axis of the functional image sensor 104. Generally speaking, since the entire lens assembly will eventually be mounted on a sensor board having a functional image sensor in a finished form mounted on the sensor board, the overall optical axis 28 should be substantially perpendicular to the image plane of such a functional image sensor 104. This will help to ensure a more precise alignment between the lens assembly and the functional image sensor, which will be used with the lens element in the assembled camera module.

[0021] In order to achieve such alignment between the lens elements 16, 18, 20, 22, 24 of the lens assembly with high productivity, a rough alignment between the lens elements should be performed first. The rough alignment is used to quickly align the optical axis of the separated lens element 24 in the lens assembly with the optical axes of the remaining lens elements, and the rough alignment can be achieved by optically detecting multiple surfaces of the lens elements. This rough alignment should also orient the optical axis to be substantially perpendicular to the expected image plane of the functional image sensor in the finished camera module. However, when this rough alignment is used to achieve an approximate alignment of the respective optical axes, since it is not accurate enough in itself, a fine alignment should be subsequently implemented to perform a higher precision alignment.

[0022] Regarding the coarse alignment process, Figure 3A1 is an isometric view of an optical detector 30 for measuring the spherical surface of at least one lens element included in the interlocking lens holder 10. In the present embodiment, since the interlocking lens holder 10 includes four individual lens elements 16, 18, 20, 22, only the lens element 22 located at the top of the interlocking lens holder 10 is measured in order to improve productivity. This measurement involves measuring the spherical profile of the surfaces of both sides of the lens element 22. Therefore, the optical detector 30 can be, for example, a 3D scanner or a laser leveling sensor, which can not only inspect and measure the spherical profile of the side of the lens element 22 facing it, but also "see through" the lens element 22 to inspect the opposite side of the lens element 22.

[0023] Therefore, in this embodiment, only the optical axis of the top lens element 22 is measured, while the remaining lens elements 16, 18, 20 in the lens assembly installed in the interlocking lens holder 10 are ignored. When there is a residual alignment error between the top lens element 22 and the remaining lens elements in the interlocking lens holder 10, the fine alignment used later in the process can still optimize the image quality in the final active alignment process. However, if desired and the cycle time is not limited, the optical detector 30 may look away from the top lens element 22 and measure the spherical profile of each of the other lens elements 16, 18, 20 included in the interlocking lens holder 10.

[0024] In addition to measuring the surface of the top lens element 22 included in the interlocking lens holder 10, Figure 3B 3 is an isometric view of an optical detector 30 for measuring the spherical surface of the separator lens element 24. The optical detector 30 is located on one side of the separator lens element 24 to inspect and measure the spherical profile of a first surface of the separator lens element 24 facing the optical detector 30, and the optical detector 30 is also used to inspect and measure the spherical profile of a second surface of the separator lens element 24 opposite the first surface through the first surface. Therefore, the measurement of both sides of the spherical surface of the separator lens element 24 is similar.

[0025] Figure 4A The measured spherical profile of the top lens element 22 included in the interlocking lens holder 10 is shown. A first spherical profile S1 of a first side surface and a second spherical profile S2 of a second side surface of the top lens element 22 are obtained. A first spherical center C1 calculated according to the first spherical profile S1 is obtained based on the first spherical profile S1. Similarly, a second spherical center C2 calculated according to the second spherical profile S2 is further obtained based on the second spherical profile S2. Therefore, the approximate optical axis 32 of the top lens element 22 is determined as a straight line passing through C1 and C2.

[0026] Figure 4BThe measured spherical profile of the separation lens element 24 assembled on the separation lens holder 26 is shown. A first spherical profile S1 of a first side surface and a second spherical profile S2 of a second side surface of the separation lens element 24 are obtained. Based on the first spherical profile S1, a first spherical center C1 calculated according to the first spherical profile S1 is obtained. Similarly, based on the second spherical profile S2, a second spherical center C2 calculated according to the second spherical profile S2 can also be obtained. Therefore, the approximate optical axis 34 of the separation lens element 24 is determined as a straight line passing through C1 and C2. For rough alignment, the optical axis 32 of the top lens element 22 should be coaxially arranged with the optical axis 34 of the separation lens element 24 so that the optical axes 32 and 34 are coaxially aligned.

[0027] Furthermore, during the coarse alignment, the optical axes 32 and 34 of each lens module are aligned with the reference points provided by the alignment system. Based on this, the relative optical displacement between the two lens modules and the overall optical axis 28 are adjusted to align the desired imaging plane of the image sensor for performing AA.

[0028] Therefore, the rough search system optically measures the curvature of each lens surface to determine the spherical center of each lens surface. Based on the spherical centers C1, C2 of the two lens surfaces of each lens element 22, 24, the optical axis 32, 34 of each lens element 22, 24 can be determined.

[0029] Figure 5 The layout of a lens alignment device 38 for performing the alignment process according to a preferred embodiment of the present invention is shown. The lens alignment device 38 provides a solution for quickly aligning two lens modules to achieve the best overall lens imaging quality of the lens assembly.

[0030] In the lens alignment apparatus 38 shown, a twelve-axis processing system holds and manipulates the first and second lens modules and can adjust each lens module within six degrees of freedom (DoF) (i.e., each lens module is adjustable in X, Y, Z, and rotational directions). In general, a coarse search system first measures the decentering displacement in the optical axes 32, 34 of the first and second lens modules with micron-level accuracy and measures the tilt or rotational displacement within a number of arc minutes. Based on the measurement feedback, the processing system is able to coarsely align each lens module within six degrees of freedom.

[0031] Secondly, an image quality index about the two lens modules is obtained by using a precision search system including a golden image sensor and a test chart. Since the image quality in the precision search system is sensitive to the order of sub-micron decentering displacement and arc-second tilt displacement of the two lens modules, the processing system can align the two lens modules with very high accuracy according to the feedback of the image quality. After the two lens modules are aligned at the optimal position relative to each other, an adhesive is spread on the connecting surface of the lens modules to fix the lens modules to each other.

[0032] In more detail, the lens alignment apparatus 38 has a first gripper 40 for gripping the interlocking lens holder 10 and a second gripper 42 for gripping the separate lens holder 26. The first gripper 40 and the second gripper 42 are respectively capable of orienting the interlocking lens holder 10 and the separate lens holder 26 in six degrees of freedom to align the plurality of lens elements assembled in the interlocking lens holder 10 and the separate lens element 24 assembled on the separate lens holder 26. Therefore, the first gripper 40 and the second gripper 42 enable the lens alignment apparatus 38 to manipulate and align the lens elements 16, 18, 20, 22, 24 in twelve degrees of freedom.

[0033] The first gripper 40 and the second gripper 42 are operably connected to the main control system 46 to control their respective movements. During the rough search, the rough search system 48 provides data on the optical axis 32 of the top lens element 22 and the optical axis 34 of the separate lens element 24 so that the main control system 46 instructs the first gripper 40 and the second gripper 42 to manipulate the optical axes 32, 34 to be coaxial with each other. To this end, the optical detector 30 can be respectively located above the first lens module (including the plurality of lens elements in the interlocking lens frame 10) and the second lens module (including the separate lens frame 26) to measure the above-mentioned Figure 3A , Figure 3B , Figure 4A and Figure 4B The top lens element 22 and the separation lens element 24 have spherical surface profiles S1, S2.

[0034] For fine alignment, a fine search imaging system 50 is also provided, which is operably connected to the main control system 46. The fine search imaging system 50 is electrically connected to the image sensor 14, which is used to view or observe the test chart 44 through the lens elements 16, 18, 20, 22, 24 included in the first lens module and the second lens module. The test chart 44 is arranged so that the field of view from the separated lens element 24 to the test chart 44 has an angle θ.

[0035] During the fine alignment process, the fine search imaging system 50 generates various quality parameters related to the image captured by the image sensor 14. These quality parameters may include, but are not limited to, optical transfer function (OTF), modulation transfer function (MTF), spatial frequency response (SFR), contrast transfer function (CTF), TV line, or any other evaluation method known in the art that can represent the resolution of the imaging system. In addition, in order to obtain more accurate quality parameters, the image sensor 14 used should preferably be a golden mirror sensor, which is a known and preferably high-quality standard sensor and serves as a reference point to measure all lens elements that need to be aligned.

[0036] In particular, the fine search imaging system 50 has a positioning stage 45 for moving along a single axis toward or away from the test pattern 44. The image sensor 14 is located on the positioning stage 45. Figure 5 In the figure, the movement is represented by the vertical uniaxial movement of the sensor plate 12. According to the through-focus scanning of the image sensor 14 by the fine search imaging system 50, a plurality of imaging quality curves (such as MTF, SFR or related illumination curves, etc.) about the image of the test pattern 44 can be obtained. Based on these imaging quality curves, certain lens imaging quality indexes (such as peak MTF, imaging plane tilt, lens field curvature tilt, sagittal and tangential MTF peak separation, etc.) can be obtained.

[0037] In general, each lens element is designed with a specific optical model of imaging quality variations based on decentration, tilt and gap shifts associated with the first lens module and the second lens module. Thus, according to the above optical model, even a small shift between the first lens module and the second lens module can be calculated and the lens modules can be further aligned relative to each other.

[0038] Figure 6 6 is a flow chart of an exemplary alignment process. In step 60, a handling system including a first gripper 40 and a second gripper 42 holds a first lens module and a second lens module, wherein the first lens module includes lens elements 16, 18, 20, 22 assembled in an interlocking lens holder 10, and in this embodiment, a separate lens element 24 is assembled on a separate lens holder 26. In step 62, an optical detector 30 measures the optical axis 32 of the top lens element 22 and the optical axis 34 of the separate lens element 24 during the rough alignment process as described above.

[0039] In step 64, if the optical axes 32, 34 are not axially aligned to within the predetermined specifications, then in step 66, the processing system further adjusts the lens elements 22, 24 to better align the optical axes of the lens elements before checking the alignment again. Once it is determined that the coarse alignment is within the predetermined specifications, the processing system measures a lens image quality index during the fine search in step 68. The lens image quality index may include one or more quality parameters captured by the image sensor 14 as described above.

[0040] In step 70, the first gripper 40 and the second gripper 42 move and adjust the lens elements 22, 24 relative to each other based on the obtained lens image quality index. In step 72, it is determined whether the inter-shifts between the lens elements 22, 24 make the image quality meet the predetermined quality requirements. If not, in step 74, the processing system will further fine-align the lens elements 22, 24 relative to each other before checking again whether the inter-shifts between the lens elements 22, 24 make the image quality meet the predetermined quality requirements.

[0041] Once the desired image quality is achieved, an adhesive, such as glue, is dispensed between the first lens module and the second lens module in step 76. After the lens modules are fixed to each other by curing in step 78, the assembly is complete (step 80).

[0042] Figure 7 An adhesive dispenser 90 is shown dispensing adhesive 92 onto the interlocking lens holder 10. The adhesive 92 may be an ultra-violet light-activated adhesive. Figure 8 In the embodiment, the split lens element 24 assembled on the split lens holder 26 is fixed to the other lens elements 16, 18, 20, 22 by placing the split lens holder 26 on the adhesive 92. If the adhesive 92 is a UV-activated adhesive, the adhesive 92 is cured by using the UV lighting system 94 to solidify the bond between the split lens holder 26 and the interlocking lens holder 10 (the split lens element 24 is in the aligned position).

[0043] In summary, the alignment method according to the present invention provides a system method for quickly aligning a first lens module and a second lens module that are combined to form a lens assembly. The method proposes a hardware system with a dual-path alignment method and a processing system including two six-axis motion systems, which respectively hold and manipulate the first lens module and the second lens module relative to each other. The dual-path alignment method combines a rough search process and a fine search process to quickly align the relative positions of the two lens modules in the X, Y, Z directions and the rotational direction. The rough search system quickly measures and aligns the optical axes of the two lens modules with sub-millimeter to micron-level accuracy. The precise search system includes a test chart and a golden mirror sensor 14, wherein the golden mirror sensor 14 is mounted on a positioning table for measuring the imaging quality of the lens, and performs closed-loop feedback based on the obtained imaging quality index. Therefore, the alignment accuracy can be further improved to sub-micron accuracy. Finally, an adhesive application system is used to disperse an adhesive (e.g., UV glue or UV hot glue) between the connecting surfaces of the respective lens modules. To cure the glue, an ultraviolet lighting system 94 is used to cure the glue on the connecting surfaces of the two lens modules to complete the construction of the lens assembly.

[0044] It should be understood that the method according to the embodiment of the present invention as described above has the benefits of improving yield, accuracy and speed.

[0045] In the conventional lens assembly process, the design of the lens system with a large number of lens elements leads to a decrease in yield, compared with which the method of the present invention can achieve an increase in yield. The method of the present invention can significantly improve the yield by implementing an AA process including accurate measurement of the lens imaging quality.

[0046] The accuracy is improved because the image quality obtained from the golden mirror sensor 14 can show slight misalignment between the first lens module and the second lens module. In addition, the twelve-axis processing system including the lens alignment device 38 that performs full-focus scanning along at least one axis of motion provides high-precision motion and sufficient degrees of freedom (DoF) to adjust any misalignment between the first and second lens modules.

[0047] In addition, the dual path alignment method can quickly perform a rough alignment of the first lens module and the second lens module, and measure and align the optical axes of the respective lens elements during this process. This rough search of the optical axis 32, 34 of each lens element only requires the capture of one image and can be completed efficiently within a short image capture time frame. Because the rough search system does not require additional movement (e.g., rotation or scanning) of the lens to measure the optical axis, this portion of the alignment can be completed faster than conventional methods for aligning multiple lens elements, and the subsequent fine search makes the alignment more accurate.

[0048] In addition to the above specific description, the present invention described herein may also be changed, modified and / or added. And it should be understood that the present invention includes all such changes, modifications and / or additions, and these changes, modifications and / or additions all fall within the spirit and scope of the present invention described above.

Claims

1. A method for aligning a plurality of lens elements included in a lens assembly, comprising the steps of: separating the lens assembly into a first lens module including at least one lens element of the plurality of lens elements and a second lens module including the remaining lens elements of the plurality of lens elements, wherein the lens elements are included in the lens assembly; determining an optical axis of at least one lens element included in the first lens module by measuring a spherical profile of each of the two side surfaces of at least one lens element included in the first lens module using an optical detector, determining an optical axis of at least one lens element included in the second lens module by measuring a spherical profile of each of the two side surfaces of at least one lens element included in the second lens module using an optical detector, and coaxially aligning the determined optical axes to perform coarse alignment between the first lens module and the second lens module to correct any tilt or rotation offset between them relative to a desired imaging plane of an image sensor; When the first lens module and the second lens module are located between the test chart and the image sensor, viewing the test chart through the image sensor; performing fine alignment between the first lens module and the second lens module by obtaining an image quality index from an image sensor of the test chart at different relative alignments between the first lens module and the second lens module; Then, The first lens module is secured to the second lens module at a relative alignment between the first lens module and the second lens module that optimizes the image quality index.

2. The method according to claim 1, wherein: The first lens module includes a plurality of lens elements and the second lens module includes a single lens element, wherein the coarse alignment includes aligning an optical axis of a top lens element included in the first lens element with an optical axis of a single lens element included in the second lens element.

3. The method according to claim 1, wherein: With respect to each of said at least one lens element, said method further comprises the following steps: Calculating a first spherical center according to a spherical profile of a first surface of the lens element; calculating a second spherical center according to a spherical contour of a second surface of the lens element opposite to the first surface; and The optical axis of the lens element is obtained by a straight line passing through the first spherical center and the second spherical center.

4. The method according to claim 3, wherein: The step of aligning the optical axis of at least one lens element in the first lens module and the second lens module includes coaxially aligning a straight line passing through a first spherical center and a second spherical center of the lens elements of the first lens module and the second lens module.

5. The method according to claim 1, wherein: The optical detector includes a three-dimensional scanner or a laser leveling sensor.

6. The method according to claim 1, wherein: The optical detector is located on one side of the at least one lens element, and is used to inspect and measure the spherical profile of a first surface of the lens element facing the optical detector, and is used to inspect and measure the spherical profile of a second surface of the lens element opposite to the first surface through the first surface.

7. The method according to claim 1, wherein: The steps of performing coarse alignment and fine alignment also include grabbing the first lens module using a first gripper, grabbing the second lens module using a second gripper, and viewing the test chart through the image sensor while manipulating the first lens module and the second lens module using the first gripper and the second gripper.

8. The method according to claim 7, wherein: The first gripper and the second gripper are respectively used to manipulate the first lens module or the second lens module within six degrees of freedom.

9. The method of claim 1, further comprising observing the test chart through the lens elements included in the first and second lens modules using a fine search imaging system electrically connected to the image sensor.

10. The method according to claim 9, wherein: During the fine alignment process, the fine search imaging system generates a plurality of quality parameters associated with images captured by the image sensor.

11. The method according to claim 10, wherein: The quality parameter is selected from the group consisting of optical transfer function, modulation transfer function, spatial frequency response, contrast transfer function, and television lines.

12. The method according to claim 9, further comprising the steps of positioning the image sensor on a positioning stage that moves along a single axis, and performing full-focus scanning by moving the image sensor along the single axis to obtain the image quality index.

13. The method according to claim 1, wherein: The image sensor is a golden mirror sensor.

14. The method according to claim 1, wherein: The step of fixing the first lens module on the second lens module also includes dispersing a UV-active adhesive on the first lens module and / or the second lens module to make the connection surfaces of the first lens module and the second lens module adhere to each other, and curing the UV-active adhesive using UV rays.

15. The method of claim 1, further comprising the step of mounting the first lens module and the second lens module on a sensor board having a finished functional image sensor mounted thereon.

16. The method according to claim 15, wherein: The step of coarsely aligning further includes orienting the optical axis substantially perpendicular to an intended image plane of the functional image sensor.

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