Method for determining assembly scheme for combination of N optical elements and optical module produced thereby

Abstract

The invention relates to a method for determining an assembly scheme for an optical element, such as an optical lens, for equipping an optical module, said module having a stack axis (z) and a reference plane (x, y) perpendicular to the stack axis, and comprising a combination of N types of optical lenses (Lk), k = [1,... N], provided with two interfaces f and mounted in a lens barrel (10), the method is intended to determine, for a subset of the n lenses, a rotation angle [theta] k with respect to a reference angular position [theta] 0, which corresponds to the closest spacing of the projections of the 2n vertices (COk, f) of said subset on the reference plane (x, y).

Description

[0001] The present invention relates to a method for determining an assembly scheme for a combination of N optical elements forming an optical module, and more specifically, a combination of N optical lenses made of molds, the molds themselves consisting of multiple cavities. Existing technology

[0002] Optical systems (such as lens assemblies used in smartphone cameras and camcorders) typically consist of components of optical parts, primarily individual lenses stacked within support structures such as lens barrels. These optical modules are then assembled with CMOS or CCD sensors to form a camera module.

[0003] Due to their small size, the production of these lenses involves design uncertainties and requires special monitoring of molding parameters such as molding time, temperature, and pressure profiles.

[0004] During the molding stage, a measuring tool based on an atomic force microscope (sold under the name UA3P) is used to check the shape and thickness, compare them with theoretical values, and ensure that the measurements are within the specified tolerances.

[0005] Despite these controls, the vertices of each interface will typically deviate slightly from the center of the support defined by the lens connection area, especially due to the thermal shrinkage effect during the molding process.

[0006] To compensate for these offsets, it is known to perform extensive empirical rotations on the individual lenses to reduce these offsets and improve the optical quality of the lens assembly.

[0007] However, these experimental designs involve performing a large number of rotations sequentially to explore the range of possible combinations. Summary of the Invention

[0008] To this end, the present invention proposes a method for identifying the optimal rotation to be performed with a minimum number of steps and rotation tests, so that the vertices of each interface of these lenses are optimally aligned along the optical axis in the assembled lens barrel.

[0009] This invention particularly relates to a method for determining an assembly scheme for a combination of N optical elements, wherein the optical elements form an optical lens assembly when stacked in a lens barrel along a stacking direction substantially aligned with the optical axis, at least one of the optical elements includes two optical interfaces, each optical interface including a vertex, and for each optical element in a subset of the N optical elements of the combination, the method includes the following steps:

[0010] -Based on the orientation of the optical element at least two angles around the stacking direction, determine the vertex trajectory for each optical interface of the optical element in a plane (x, y) perpendicular to the stacking direction (z).

[0011] - In the plane (x, y) perpendicular to the stacking direction (z), the coordinates of the vertices of each optical interface of the optical element are determined, which verify the shortened distance of the trajectories of the other optical elements relative to a subset of n optical elements, and

[0012] - Determine the angular orientation of the optical element, wherein the vertices of the two interfaces of the optical element are closest to the trajectories of other optical elements in a subset of n optical elements.

[0013] This requires a so-called global minimization step, where a set of rotation angles Θ is determined globally by computation. k That is, the rotation of n lenses so that the vertices of each interface are positioned as close to each other as possible.

[0014] This set of angles Θ can be obtained using a global minimization algorithm. k For example, a modified Traveling Salesman Minimization (TSM) algorithm to fit the problem at hand, which minimizes the sum of distances the traveler needs to cover, in this case, the distances between vertices.

[0015] This invention provides various embodiments, incorporating different optional features set forth below, according to all possible combinations thereof.

[0016] According to a first preferred aspect of the invention, the optical element is an optical lens with an aspherical, axisymmetric profile, more specifically, having a substantially flat and circular peripheral region that defines a support center and provides support during assembly of the lens into the lens barrel. Each lens contributes its optical function to the overall optical function of the lens assembly, and each of the two interfaces of each lens has a central region, the vertex position of which (i.e., the apparent center of each interface along the optical axis of the lens assembly) is the object of optimization.

[0017] The method is characterized by comprising a set of steps for determining the optimal angular orientation of a subset of n types of optical lenses selected from N types of optical lenses, namely:

[0018] - The steps of mounting the N types of optical lenses in the lens barrel at a reference angular position Θ0 and measuring the position of the vertex of each interface.

[0019] - For a subset of n lens types selected from N lens types, the step of determining vertex trajectories for several different lens assemblies by rotating the n lens types about an optical axis passing through their support centers. The position of the trajectory projected onto a reference plane is calculated by analyzing the obtained measurement results; this trajectory represents the displacement of each vertex of each interface as the lens rotates about an optical axis passing through its support center.

[0020] Then, an algorithm is used to generate the shortened distance point DR by searching for steps to shorten the distance point DR and steps to minimize the distance to DR, namely:

[0021] - The steps to calculate and determine the coordinates of the projection of the shortened distance point DR to the reference plane onto the reference plane.

[0022] - For each pair of trajectories (associated with one of the two interfaces), the step of calculating the coordinates of the two points closest to the shortened distance point DR.

[0023] The rotation angle Θ relative to the reference angular position Θ0 is calculated based on two points associated with one of the two interfaces of each of the n types of lenses. k This allows the vertices of each interface to be positioned at the point that is closest to the point of shortening the distance overall.

[0024] Preferably, once the rotation angle is determined, the step is performed: wherein the measurement is performed by including the measurement based on its eigenangle Θ. k The quality characteristic value of a lens assembly obtained by combining N types of lenses, including n directional lenses.

[0025] Advantageously, the steps are performed to pass through, including according to its eigenangle Θ k The measured values ​​of the quality characteristics of the lens assembly obtained by combining a subset of N types of lenses of n directional types are compared with a first predefined threshold.

[0026] This first threshold defines whether a component thus completed is acceptable in terms of quality.

[0027] Preferably, the quality characteristic value of the lens assembly is the value of the modulation transfer function (MTF).

[0028] According to a second preferred aspect of the invention, the step of determining the trajectory representing the displacement of a vertex includes:

[0029] - Sub-step, wherein, for each of the n lens types, the coordinates of the projected vertex in the reference plane at the reference angular position Θ0 are measured.

[0030] - A sub-step where the desired trajectory is a circle, wherein each of the n types of lenses is rotated 180 degrees about the optical axis passing through its support center to place it in angular position Θ. 180 This allows for the formation of several lens assemblies, such as two, for the n lens sub-parts of the lens assembly.

[0031] If the desired trajectory is not a circle, perform more rotations, such as four non-circular rotations (with a 90° difference), or if the trajectory is an ellipse, preferably perform five rotations (with a 72° difference).

[0032] - Sub-step, wherein for each of the n lens types, the equation of the projection trajectory of each vertex in the reference plane is calculated.

[0033] The rotational guidance of the lens can be determined simply by assembling the lens barrel. In this case, the rotation of lens L... k The trajectory equations for each lens obtained are independent of the rotation of adjacent individual lenses.

[0034] In more complex designs, individual lenses can have assembly shoulders that contact adjacent individual lenses. If these shoulders are well aligned relative to the lens barrel, they do not significantly alter the rotational guidance of the lens barrel. Otherwise, each individual lens L... k The trajectory position may depend slightly on the individual lens L k-1 and / or a single lens L k+1 The rotation of lens L. At this point, a series of rotations of lens L can be completed. k (e.g., even k) and the steps of measuring with several rotations of adjacent supported lenses (e.g., odd k) to add and determine coefficients for quantifying the rotational coupling effect of adjacent lenses, which is, in a first-order approximation, equivalent to measuring the lens L according to the rotation of adjacent lenses. k The rotational displacement is parameterized: in the case of a circular trajectory, the lens L k The diameter of the circle at each interface f may be substantially constant, but its center position is affected by the contact lens or two lenses (L). k-1 and / or L k+1 The rotation of the lens and, optionally, the further lens L k-2 and L k+2 Rotational modulation.

[0035] In this case, based on the analysis of additional experiments on the rotation of adjacent individual lenses, the coupling coefficient between, for example, the center movement of the trajectory circle and the rotation of these adjacent individual lenses is determined.

[0036] Similarly, in a single lens L k When there are angles (tilt angle and tilt angle) between the supporting surfaces, these additional coupling coefficients may need to be considered.

[0037] The remainder of this disclosure is based on the assumption that the trajectory of the apparent center of each interface is a circle, but other types of trajectories are possible, and that the method is adaptive, for example by adding two values ​​(Θ0 and Θ) to each individual lens. 180 The values ​​of test angles other than θ0 are used to determine the parameter set of these trajectories. Using two points known to be the diameter of a circle, its radius and center can be determined. Three points Θ0, Θ2, Θ3, Θ4, Θ5, Θ6, Θ7, Θ8, Θ9, Θ1, Θ1, Θ2, Θ1, Θ2, Θ3, Θ4, Θ5, Θ6, Θ7, 120 Θ -120 This allows for greater redundancy and noise resistance when determining a circular trajectory. The major axis, minor axis, and center of the ellipse can be determined using four points (non-concyclic) or preferably five points.

[0038] Advantageously, the vertex coordinates are measured using the low-coherence interferometry technique disclosed in document WO2023 / 057539A1.

[0039] Similarly advantageously, in addition to for multiple angles (e.g., Θ0 and Θ), 180 In addition to measuring the vertex coordinates, the thickness of n individual lenses of different types at the vertex is also measured. This measurement verifies that the thickness is within specified tolerances. These thicknesses can also be modified if needed.

[0040] Similarly advantageously, in addition to for multiple angles (e.g., Θ0 and Θ), 180 In addition to measuring the vertex coordinates, the angular deviations of n individual lens-type planes at the vertex can also be measured. These planes can be defined as an average plane, a plane tangent to the interface of an individual lens, or a plane perpendicular to the rotational symmetry normal vector of each individual lens interface.

[0041] In fact, the plane of each lens can be slightly tilted along the (y) axis, forming a so-called "tilt" angle with respect to the optical axis (z), or tilted along the (x) axis, forming a so-called "tilt angle" with respect to the optical axis (z).

[0042] According to a third preferred aspect of the invention, when the optical module includes one or more spacers of variable thickness (spacers for insertion between some of N types of individual lenses), all steps aimed at determining the optimal angular orientation of each of the n types of individual optical lenses are performed by changing the thickness of the spacers, and then the thickness of the spacers is adjusted. This step can be performed during the angle optimization phase, or by including adjustments based on their intrinsic angle Θ. k The process is performed when the quality characteristic value of the lens assembly obtained by combining a subset of N individual lenses of n types is greater than a first predefined threshold.

[0043] Therefore, for a combination of N individual lenses of acceptable quality, the assembly can be optimized by modifying the thickness of the spacers.

[0044] According to a fourth preferred aspect of the invention, each of the N types of individual lenses is derived from a manufacturing mold comprising M cavities, all steps are performed to determine the optimal angular orientation of a subset of n types of individual lenses selected from the N types of individual lenses, and preferably performed in parallel for the M cavities, i.e., simultaneously performing M assemblies of the N types of individual lenses, exposing their angular variations, and determining a trajectory for each individual lens in each series of lens assemblies from each cavity.

[0045] On the one hand, this enables the parallel optimization of M components, or optimization on a subset of m individual lenses selected from the M components (e.g., in the case where one or more unusable cavities exist such that m is less than M), the subset of m individual lenses being the production target of molding M cavities for each type of individual lens.

[0046] However, according to the fifth aspect of the invention, this makes it possible to compare the trajectories between components obtained through calculated permutation in the computational step to find a better solution than without permutation. Permutation refers to the computational simulation of several lens assemblies, each made of several different cavities, such as lens L1 (k=1) from cavity 1, lens L2 from cavity 5, lens L3 from cavity 12, and so on. (Such a permutation performed by calculation closely approximates the result obtained by actually measuring and realizing the trajectory of the lens center, provided, for example, the lens is guided fairly well by supports in the assembled lens barrel during rotation, or the alignment quality of the support area is fairly good.)

[0047] Alternatively, even if this increases the number of physical tests to be performed, several physical substitutions within the meaning of the second aspect can be performed to provide real support trajectory data for the calculation steps of the fifth aspect using the substituted lenses, thereby selecting different lens combinations that provide better alignment for the manufactured set of lens assemblies.

[0048] Therefore, the cavity is replaced to improve the quality of the manufactured lens assembly, and these replacements are performed during the calculation steps or when the lens is mounted in the lens barrel.

[0049] Therefore, preferably, a combination of N types of optical lenses is determined (including according to their intrinsic angle Θ). k,j A subset of n types of optical lenses with optimal orientation (and the lens is selected from a subset of m cavities from M cavities), which overall provides the best quality characteristic values ​​for each of the m lens assemblies.

[0050] Preferably, the set of parameters to be checked when leaving the manufacturing mold includes shape, thickness, eccentricity, angular deviation from the (x, y) plane, and optical refractive index.

[0051] Another object of the present invention is an optical module obtained by performing the method according to the invention, wherein the modulation transfer function (MTF) of the optical module is higher than a first predetermined threshold.

[0052] According to a sixth preferred aspect of the invention, the angle (Θ) can be adjusted. k To further improve the obtained optical quality, small variations are made to optimize the set of angles obtained at the end of one of the aforementioned steps. This is achieved by adjusting the angles close to the eigenangle value Θ. k The angle value is used to measure a series of characteristic values ​​of the lens assembly's mass, while controlling the increase of these characteristic values. For example, the Newton gradient method can be used.

[0053] The lens assembly manufactured according to the present invention can be used in particular for the production of camera modules for smartphones, digital tablets, computers, webcams, etc.

[0054] The lens assembly manufactured according to the present invention can also be used in the mass production of camera modules for automobiles, for example, as a driver assistance system or to provide power for an autonomous driving system, or for image acquisition or driving of flight systems (such as airplanes, drones, helicopters, etc.).

[0055] The lens assembly manufactured according to the present invention can also be used to assemble camera modules for medical use (e.g., camera modules used in endoscopes) or camera modules for video surveillance.

[0056] Of course, these examples are not restrictive.

[0057] List of Attachments

[0058] Other features and advantages will become apparent from the detailed description and accompanying drawings of the completely non-limiting embodiments, wherein:

[0059] - [ Figure 1 [Illustration] is a schematic longitudinal cross-sectional view of an optical module according to an embodiment of the present invention.

[0060] - [ Figure 2 [Illustrated top view of a lens of an optical module according to an embodiment of the present invention.]

[0061] - [ Figure 3 [Illustrated longitudinal cross-sectional view of a lens-type optical component according to an embodiment of the present invention.]

[0062] - [ Figure 4 [Illustration] is an explanatory diagram of an embodiment of the present invention. Detailed Implementation

[0063] Figure 1 A schematic longitudinal sectional view of an optical module 1 for assembling optical lens assemblies is shown.

[0064] The module has an optical axis (z) and a reference plane (x, y) perpendicular to the optical axis, and includes N types of optical lenses L mounted in the lens barrel 10. k The combination of k = [1, ..., N].

[0065] The optical module may also include one or more spacers Si, which have a variable thickness e i , i=[1,...E], designed for insertion between certain lenses of N types of lenses.

[0066] like Figure 2 As shown, lens L k Each of the interfaces has an axisymmetric profile of a non-spherical type, more specifically, has a substantially flat circular peripheral region MEC. k,f The outer region defines the support center CM k,f And designed to provide support when the lens is mounted in the lens barrel; and having a connection with each lens L k The central region OPT related to optical functions k,f The apparent center of the central region of each interface defines what we call the vertex CO. k,f , where f takes the value 1 or 2 for each interface. It should be noted that the optimizations involved in this method aim to make these vertices CO... k,f Align them as closely as possible along the same axis, which is also the optical axis of the lens assembly.

[0067] The method according to the invention includes determining n types of optical lenses L selected from N types of optical lenses. k A set of steps for optimal angle orientation of a subset of .

[0068] The method first includes placing N types of optical lenses L k The procedure involves mounting the lens in the telescope barrel at a reference angle position Θ0. This reference position can be determined by visual markings on the telescope barrel and the optical lens L. k It is constructed by aligning visual markers on the top.

[0069] like Figure 4 As shown, the method then includes selecting n types of lenses from N types of lenses, and for a subset of the n types of lenses, by making them themselves orbit around their respective support centers CM. k,f Rotate along the optical axis (z) to determine the vertices CO that represent them, projected onto the reference plane (x, y).k,f Regarding the passage through their respective support centers CM k,f The displacement of the optical axis (z) by n circles C-Shift k,f The steps of the equation. In fact, especially due to the thermal shrinkage effect during the molding process, the vertex CO k,f It usually deviates slightly from the support center CM k,f .

[0070] A subset of the n lens types out of the N lens types can take the form of, for example, a subset where k is even, odd, equal to 1, or N, or a subset of lens types whose shape makes any eccentricity more sensitive to the overall optical function than other lens types. Of course, given the small number of components to be tested, it is perfectly acceptable to take n=N to obtain the best possible quality at the end of this method, without making the method more difficult to implement in practice.

[0071] Based on the principle of determining the shortened distance point DR, the method then includes calculating and determining 2n circles C-Shift projected onto the reference plane (x, y). k,f The coordinates (x) of the shortened distance point of the trajectory of the group DR y DR The steps are as follows.

[0072] For example, the coordinates (x) of the shortened distance point (DR) DR y DR ) can be compared with trajectory (CI) k,f p k The list of neighboring or intersection points between p is determined by the associated Leibniz vector function, k=[1,...n], p k Represents each circle's C-Shift k,f The weight is a function of the sensitivity of the refractive index interface k,f to the overall optical function.

[0073] Then, the method includes for each circle C-Shift k,f Calculate the circle C-Shift k,f The point M that is closest to the point where the distance is shortened k,f The steps for obtaining the coordinates.

[0074] The following steps can be used to calculate the shortened distance point (DR):

[0075] (a) For each pair of lenses, calculate the intersection of every pair of trajectories (with respect to the two interfaces f). This results in a set of points, usually an even number (except for the case of tangent circles), ranging from 0 to 8. If these circles do not intersect, take a single point equidistant from the nearest circle. For example, we get A(2, n) (the number of binomial coefficients for taking 2 elements from n elements) sets of 8 points.

[0076] (b) Take all pairs of 2 from the previous A(2,n) groups (considering A(2, A(2,n))). For each pair of groups with a maximum of eight points, remove the point that is furthest from the others.

[0077] Further optimizations can be made in steps (a) and (b), for example by applying a more global approach to select the points to keep, or by repeatedly traversing and selecting based on different paths through the list of points.

[0078] (c) For example, calculate the centroid of the group of points remaining from steps (a) and (b). This centroid is considered as the shortened distance DR of the circle in that group.

[0079] Finally, the method includes calculating the rotation angle Θ relative to the reference angular position Θ0 for n types of lenses. k The steps involve the reference angle position corresponding to the vertex CO of the closest point DR. k,f Positioning.

[0080] Therefore, for each lens L in the subset of n optical lens types k The rotation angle Θ to be applied has been defined. k To realign the 2n vertices CO as well as possible. k,f .

[0081] This method assumes that the plane of each lens is parallel to the reference plane (x, y), which is not entirely accurate because the plane of each lens may be slightly tilted along the (y) axis, forming a so-called "tilt" angle with the optical axis (z), such as... Figure 3 As shown, or tilted along the (x) axis, forming a so-called "tilt" angle with the optical axis (z).

[0082] Therefore, when the lens rotates, the trajectory C-Shift projected onto the reference plane (x, y) k,f (representing the vertex CO of the lens) k,f Around CM that passes through their respective support centers k,f The displacement trajectory during the rotation of the optical axis (z) is actually imperfect.

[0083] Preferably, once the n types of lenses are determined according to their eigenangles Θ kOrientation involves performing a step in which a characteristic value of the quality of the lens assembly is measured. This characteristic is obtained through a combination of N types of lenses, including measurements based on their eigenangle Θ. k n directional lenses of different types.

[0084] Then a step can be performed to pass through a combination of N types of lenses (including those based on their eigenangle Θ). k The measured values ​​of characteristic quantities of the lens (obtained by directional n types of lenses) are compared with a first predefined threshold FTMmin1 to verify or not verify the lens assembly on the lens barrel, and, if necessary, trigger the sixth aspect of the invention, or to find another shortened distance point DR, and another set of angles Θ that provides a better solution. k .

[0085] Advantageously, the quality of the lens assembly is a characteristic value of the modulation transfer function (MTF).

[0086] The optical transfer function (OTF) of an optical system is a complex function that relates the luminance in object space to the illuminance in image space. It models the effect of the optical system on the distribution of light energy in image space.

[0087] The optical transfer function is usually considered only in the conjugate object and image planes, but in general it is three-dimensional. This complex function can be decomposed into amplitude (called the modulation transfer function) and phase (called the phase transfer function).

[0088] Therefore, the modulation transfer function (MTF) is a function that characterizes the ability of an optical system to recover contrast based on the fine details of an object; in other words, it characterizes the ability of an optical system to transmit the spatial frequencies of an object. It is particularly used in photography and cinematography to evaluate the quality of optical systems.

[0089] The phase transfer function characterizes the phase shift introduced by an optical system.

[0090] According to a preferred embodiment of the present invention, the vertex CO is determined. k,f The displacement circle C-Shift k,f The steps include:

[0091] - Sub-step, where for each of the n lens types, the projection vertex CO is measured. k,f The coordinates at the reference plane (x, y) and the reference angle position Θ0.

[0092] - Sub-step, where each of the n types of lenses is arranged around its support center CM. k,f The optical axis (z) is rotated 180 degrees so that it can be placed at the angular position Θ. 180 ,

[0093] More specifically, the first lens assembly (referred to as case Θ0) can be manufactured without rotation on n lenses.

[0094] It is also possible to find all lenses L where k is an even number among n lenses. k Apply Θ 180 Rotate to leave the lens with odd k at Θ0, and create lens assembly number 2.

[0095] Θ can also be applied to all lenses k where k is odd out of n lenses. 180 Rotate to leave the lens with even k at Θ0, and manufacture lens assembly number 3.

[0096] Measure the apparent center CO of each lens interface of each of the three lens assemblies. k,f The location.

[0097] In more complex cases, where the trajectory center may depend on the rotation of adjacent lenses, lens assemblies 2 and 3 are manufactured sequentially as several lens assemblies: 2a, 2b, 2c, 2d, 3a, 3b, 3c, 3d.

[0098] In lens assemblies 2a to 2d, the lens rotation Θ is an even number (k). 180 ,and:

[0099] - No. 2a: Lens L where k is an odd number k Rotate Θ0.

[0100] - No. 2b: Lens L where k is odd and k=1 [4] (i.e., k modulo 4 is congruent to 1, i.e., k=1, 5, 9...) k Rotate Θ0, while rotating the lens k=3 [4] (k=3, 7…) by Θ. 180 .

[0101] - No. 2c: Lens L where k is an odd number k Rotation Θ 90 .

[0102] - Lens L, number 2d: k is odd and k=1 [4] (k=1, 5…) k Rotation Θ 90 The lens rotation Θ of k=3 [4] (k=3, 7…) 270 .

[0103] In lens assemblies 3a to 3d, the lens rotation Θ is an odd number for k. 180 ,and:

[0104] - No. 3a: Lens L where k is an even number k Rotate Θ0.

[0105] - No. 3b: Lens L where k is even and k=2 [4] (k=2, 6…) k Rotate Θ0, while rotating the lens k=4 [4] (k=4, 8…) by Θ. 180 .

[0106] - Lens L, number 3c: k is an even number k Rotation Θ 90 .

[0107] - Lens L, number 3d: k is even and k=2 [4] (k=2, 6…) k Rotation Θ 90 The lens rotation Θ of k=4 [4] (k=4, 8…) 270 .

[0108] For example, consider a 9-lens assembly.

[0109] The more the trajectory center dependence depends on more distant adjacent lenses, the more likely the above combination will increase to estimate the dependence coefficient of the rotation center on more distant lenses.

[0110] - Sub-step, where for each of the n types of lenses, for example based on measurements taken at the center of the three manufactured lens assemblies, the circle C-Shift projected onto the reference plane (x, y) is calculated. k,f The equation.

[0111] For example, in more complex cases, the results of nine series of measurements performed on the tested lens assembly are analyzed to determine the coupling coefficient of the trajectory center to adjacent lenses, or even the coupling coefficient of the trajectory shape to adjacent lenses.

[0112] Preferably, the vertex CO is measured using a low-coherence interferometry technique. k,f coordinate.

[0113] Interferometry is a technique that extracts information by observing the interference phenomenon caused by the superposition of waves (usually electromagnetic waves).

[0114] Interferometers are widely used in science and industry to measure minute displacements, changes in refractive index, and surface irregularities. In an interferometer, light from a single source is split into two beams, travels along different optical paths, and then recombines to produce interference. The resulting interference fringes provide information about the difference in optical path lengths. Interferometers can be used to measure the length and shape of optical components with nanometer-level precision, making them among the most accurate length measuring instruments available.

[0115] Typically, the coherence length of a laser diode ranges from tens of centimeters to several meters, while that of an LED (light-emitting diode) ranges from tens of micrometers to hundreds of micrometers. Therefore, by illuminating the interferometer with a low-coherence light source, the location where the optical path difference (OPD) is zero can be identified by finding the position where the fringes have optimal visibility. This technique can thus be used to eliminate ambiguity in fringe order (i.e., the actual displacement of the fringe system), a recurring problem in interferometry. This ensures the precision of the measurement.

[0116] Furthermore, for Θ0 and Θ 180 Measure vertex CO k,f The coordinates of the n lenses at the vertex (CO) k,f The thickness at () is measured. This measurement verifies whether the thickness is within the specified tolerance range.

[0117] Alternatively, in addition to for Θ0 and Θ 180 Measurement of vertex CO k,f In addition to coordinates, the angular deviations of n lens-type planes in the peripheral optical region of the lens can also be measured. In fact, the plane of each lens may be slightly tilted along the (y) axis, forming a so-called "tilt" angle with respect to the optical axis (z), such as... Figure 3 As shown, or tilted along the (x) axis, forming a so-called "tilt" angle with the optical axis (z).

[0118] According to a particular embodiment, the optical module may include one or more spacers Si (e.g., E spacers) having a variable thickness e. i , i=[1,...E], the spacer is designed to be inserted between some of N types of lenses.

[0119] In this case, when all steps are performed to determine the n types of optical lenses L k When orienting a subset of lenses at optimal angles, this is achieved by using a combination of N types of lenses (including those based on their eigenangles Θ). k When the quality characteristic values ​​of the lens assembly obtained from a subset of n directional lenses do not meet the requirements and need optimization, the thickness e of the spacer (Si) can be changed by incrementing i. i , where i varies from 1 to E. This situation may occur when the obtained target quality feature value is greater than the first predefined threshold FTMmin1 but less than the second predefined threshold FTMmin2.

[0120] Typically, each of the N lens types originates from M cavities M k,j Mold manufacturing k ,j=[1,...M].

[0121] In this case, for each lens L from a subset of n types of optical lenses k For M cavities M k,j Selected m cavities M k,j Perform a permutation on a subset of the set, j = [1, ..., M].

[0122] In this way, it is possible to determine the eigenangle Θ. k Directional lens L k Optimal cavity M k,j This optimizes the characteristic values ​​of the lens assembly's quality.

[0123] A subset of m cavities selected from M cavities can, for example, take the form of a subset with acceptable manufacturing quality.

[0124] Based on the first approach, which focuses on minimizing the mass of the lens assembly, N types of optical lenses L are determined. k,j The first combination includes those based on their eigenangle Θ k,j The optimal orientation of n types of optical lens types L k,j A subset of M cavities M, and that subset comes from M cavities M k,j Selected m cavities M k,j A subset of the subset whose proposed quality feature values ​​for the lens assembly are greater than a first predefined threshold (FTMmin1). Note that for each angle Θ k,j It depends on the choice of the cavity for each of the m lens assemblies assembled together.

[0125] This method can shorten the steps and determine more quickly the acceptable assembly schemes (or more precisely, the m acceptable assembly schemes) for assembling N types of lenses from each of the m mold cavities.

[0126] Based on the second approach, which focuses on the optimal quality of the lens assembly, N types of optical lenses L are determined. k,j Combinations, including those based on their eigenangle Θ k,j Optimal orientation of n types of optical lenses L k,j A subset of M cavities M, and that subset comes from M cavities M k,j Selected m cavities M k,j A subset of m lens assemblies, which proposes the best quality feature values ​​for each of the m lens assemblies.

[0127] Preferably, the lens should be removed from the manufacturing mold M before being mounted onto the lens barrel. k Each lens L k,j Perform parameter checks to eliminate lenses whose parameters deviate too far from the specified tolerances.

[0128] These parameters may include shape, thickness, eccentricity, angular deviation from the (x, y) plane, and optical refractive index.

[0129] For example, in the case where the lens assembly consists of 6 lenses, each from a mold with 16 cavities, for the first series of tests, the optimal angles of the even-numbered lenses from cavity 1, namely L2,1, L4,1, and L6,1, are calculated, and then the lens quality of the assembly is tested:

[0130] L1,1, L2,2,L3,1,L4,1,L5,1,L6,1, where L2,1,L4,1 and L6,1 are at their respective angles.

[0131] Then, through calculation, the cavities of lenses L2,j, L4,j, and L6,j are replaced, and the lens quality of the assembly is tested each time, i.e.:

[0132] L1,1,L2,2,L3,1,L4,2,L5,1,L6,2

[0133] L1,1,L2,3,L3,1,L4,3,L5,1,L6,3

[0134] L1,1,L2,4,L3,1,L4,4,L5,1,L6,4 ...

[0136] L1, 1, L2, 16, L3, 1, L4, 16, L5, 1, L6, 16

[0137] In the second series of tests, the optimal angles for the odd-numbered lenses from cavity 1, namely L1,1, L3,1 and L5,1, were calculated, and the lens quality of the assembly was tested.

[0138] L1,1, L2,2,L3,1,L4,1,L5,1,L6,1, where L1,1,L3,1 and L5,1 are at their respective angles.

[0139] Then, the cavities of lenses L1,j, L3,j, and L5,j are replaced, and the lens quality of the assembly is tested each time, i.e.:

[0140] L1, 2, L2, 1, L3, 2, L4, 1, L5, 2, L6, 1

[0141] L1, 3, L2, 1, L3, 3, L4, 1, L5, 3, L6, 1

[0142] L1, 4, L2, 1, L3, 4, L4, 1, L5, 4, L6, 1 ...

[0144] L1, 16, L2, 1, L3, 16, L4, 1, L5, 16, L6, 1

[0145] The analysis of the two series provides a comparative model of the relative vertex motion between the assembly cavities.

[0146] This provides more freedom to find better solutions.

[0147] Using this method, an analytical model of the relative positions of the displacement and angle of the vertices between cavities can also be established to test various possible components that are not actually implemented but can be simulated, thereby obtaining the optimal assembly scheme for high performance. For example, the optimal assembly scheme of 16 cavities for each type of lens can be obtained for N lenses.

[0148] This method can be used to test a relatively limited number of permutations so that mathematical calculations can be performed to determine more permutations than the reasonable number of assemblies to be manufactured and tested.

[0149] Glossary

[0150] 1 Optical Module

[0151] 10 Lens tubes

[0152] L k k-grade optical lenses

[0153] S i spacers

[0154] CO k,f The vertex of the f-th interface of a k-order optical lens

[0155] CM k,f Support center of the f-th interface of the k-th order optical lens

[0156] CI k,k' intersection

[0157] OPT k,f The central region of the f-th interface of the k-th order optical lens

[0158] MEC k,f The circular outer region of the f-th interface of the k-th order optical lens

[0159] C-Shift k,f The vertex trajectory of the f-th interface at level k

[0160] I k,f The trajectory of the f-th interface C-Shift k,f The point closest to the point where the distance is shortened

[0161] DR A set of circles C-Shift k,f shortening distance point

[0162] Θ k Rotation angle of the k-th order optical lens

[0163] Θ k,j Rotation angle of the k-th order optical lens and m parallel lens assemblies

[0164] The plane (x, y) perpendicular to the axis (z) is called the reference plane.

[0165] (z) Stacked axes, or optical axes

[0166] (M k Mold used to manufacture the kth order optical lens

[0167] (M k,j The cavity of the jth order used to manufacture the mold for the kth order optical lens.

Claims

1. A method for determining N optical elements (L k The assembly scheme of the combination of optical elements and the method of forming an optical lens assembly when the optical elements are stacked in the lens barrel (10) along the stacking direction (z), k=[1,...N], the optical elements being such as lenses, at least one of the optical elements including two optical interfaces f, f=[1,2], each optical interface including a vertex (CO). k,f For each of the subsets of the N optical elements in the combination of the N optical elements, the method includes the following steps: - Determine the vertex (CO) of each optical interface of the optical element based on at least two angular orientations of the optical element around the stacking direction. k,f The trajectory (C-Shift) in the plane (x, y) perpendicular to the stacking direction (z) k,f ), - In the plane (x, y) perpendicular to the stacking direction (z), determine the vertex (CO) of each optical interface of the optical element. k,f The coordinates of ) verify the shortened distance of the trajectories of other optical elements relative to a subset of n optical elements, and - Determine the angular orientation Θ of the optical element k Wherein, under the angular orientation, the vertices (CO) of the two interfaces of the optical element k,f The trajectory of other optical elements in the subset of the n optical elements that is closest to them.

2. The method for determining an assembly scheme according to claim 1, wherein, The optical element is a lens with an axisymmetric profile of aspherical type, and more specifically, the optical element has a defined support center (CM). k,f The basically flat circular outer region (MEC) k,f The lens, characterized in that the method includes determining n types of optical lenses (L) selected from N types of optical lenses. k The optimal angular orientation Θ of a subset of ) k A set of steps, namely: -The N types of optical lenses (L k The step of mounting the lens in the lens barrel at a reference angle position Θ0. - For a subset of the n types of lenses selected from N types of lenses, and by making the n types of lenses surround the support center (CM) k,f Rotate the axis (z) of the plane to determine the projection onto the plane (x, y) and represent its vertex (CO). k,f ) around its support center (CM) k,f The trajectory of the axis (z) displacement (C-Shift) k,f The steps of the equation, - Determine the trajectory (C-Shift) relative to the projection in the plane (x, y). k,f The coordinates (x) of the shortened distance point (DR) of the group. DR y DR The steps, - For each trajectory (C-Shift) k,f ), calculate the trajectory (C-Shift) k,f The point I closest to the shortened distance point (DR) on the ) k,f The steps for obtaining coordinates, - For the n types of lenses, calculate the rotation angle Θ relative to the reference angular position Θ0. k The step, wherein the rotation angle corresponds to the vertex (CO) k,f ) at point (I k,f The location at ) 3. The method for determining an assembly scheme according to claim 1 or 2, wherein the step of performing the step is: measuring a characteristic value of the mass of a lens assembly, the lens assembly being obtained by a combination of N types of lenses, the combination of the N types of lenses comprising measurements based on their eigenangle Θ. k n directional lenses of different types.

4. The method for determining an assembly scheme according to claim 3, wherein, For the eigenangle Θ k The intrinsic angle Θ is calculated by performing a series of measurements on the characteristic values ​​of the lens assembly's mass, and optimizing the intrinsic angle Θ while controlling the increase of the characteristic values ​​of the lens assembly's mass. k The value of .

5. The method for determining an assembly scheme according to claim 4 or 5, wherein the step of performing: comparing a characteristic value of the mass of the lens assembly with a first predefined threshold (FTMmin1), the lens assembly being obtained by a combination of N types of lenses, the combination of the N types of lenses comprising, based on their eigenangle Θ k n directional lenses of different types.

6. The method for determining an assembly scheme according to any one of claims 3 to 5, wherein, The quality of the lens assembly is characterized by the value of the modulation transfer function (MTF).

7. The method for determining an assembly scheme according to any one of the preceding claims, wherein, Represents the vertex (CO) k,f The trajectory of the displacement (C-Shift) k,f The steps of defining a circle and determining the trajectory include: - Sub-step: Wherein, for each of the n types of lenses, the vertex (CO) projected onto the reference plane (x, y) and at the reference angular position Θ0 is measured. k,f The coordinates of ) - Sub-step: wherein each of the n types of lenses is arranged around its support center (CM). k,f Rotate the optical axis (z) by 180 degrees to place it in angular position Θ. 180 , - Sub-step: Wherein, for each of the n types of lenses, the vertex (CO) projected onto the reference plane (x, y) is measured. k,f The coordinates of ) - Sub-step: Wherein, for each of the n types of lenses, calculate the circle (C-Shift) projected onto the reference plane (x, y). k,f The equation is .

8. The method for determining an assembly scheme according to the preceding claim, wherein, The vertex (CO) was measured using low-coherence interferometry. k,f Coordinate measurement.

9. The method for determining an assembly scheme according to any one of the preceding claims, wherein, In addition to measuring the vertex (CO) for multiple rotation angles k,f In addition to the coordinates of ), n types of lenses are also measured at the vertex (CO). k,f The thickness at ().

10. The method for determining an assembly scheme according to the preceding claim, wherein, In addition to measuring vertices (CO) at multiple rotation angles k,f In addition to coordinates, the angular deviation of the planes of the n lens types in the peripheral optical region of the lens is also measured.

11. The method for determining an assembly scheme according to any one of the preceding claims and in conjunction with claim 3, wherein, The optical module includes a variable thickness (e) i One or more spacers (Si), i = [1, ..., E], said spacers are used to be inserted between some of said N types of lenses, and wherein i is incremented from 1 to E to change the thickness (e) of said spacer (Si). i Perform this set of steps to determine n types of optical lenses (L k The optimal angular orientation of each lens assembly is determined to improve the quality of the lens assembly, which is obtained by combining N types of lenses, the combination of which includes features based on their intrinsic angles Θ. k A subset of n directional lenses of different types.

12. The method for determining an assembly scheme according to any one of the preceding claims, wherein, Each of the N types of lenses originates from M cavities (M k,j Manufacturing mold (M) k ), j=[1,...M], characterized in that all steps are performed to determine a subset of n lens types selected from N lens types and from said M cavities (M k,j Selected m cavities (M) k,j The optimal angular orientation Θ of a subset of ) k,j .

13. The method for determining an assembly scheme according to the preceding claim, wherein, The cavity is replaced to improve the quality of the produced lens assembly. The replacement is performed during the calculation step or when the lens is installed into the lens barrel.

14. The method for determining an assembly scheme according to claim 12 or 13, wherein, Determine N types of optical lenses (L k,j The first combination, which includes according to its eigenangle Θ k Optimal orientation of n types of optical lenses (L) k,j A subset of the M cavities (M) and derived from the M cavities. k,j The m cavities selected (M) k,j A subset of the first combination, wherein the quality feature value of the lens assembly proposed by the first combination is greater than the first predefined threshold (FTMmin1).

15. The method for determining an assembly scheme according to claim 12, wherein, Determine N types of optical lenses (L k,j Combinations of ) including those based on their eigenangle Θ k,j Optimal orientation of n types of optical lenses (L) k,j A subset of ) and from M cavities (M k,j The m cavities selected (M) k,j A subset of ), the combination of which yields the optimal characteristic values ​​for the quality of the lens assembly.

16. An optical module (1) obtained by implementing the method according to any one of the preceding claims in conjunction with claim 6, wherein the modulation transfer function (MTF) of the optical module is greater than a first predefined threshold (MTFmin1).

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