TW201426027A - Aspheric lens and measuring method thereof and photographing module - Google Patents

Abstract

An aspheric lens and a measuring method thereof, and a photographing module are provided. An optical function surface area of the aspheric lens of the invention has a shape able to achieve evaluation of high reliability though it is an aspheric lens similar to a sphere. A ring-shaped connecting surface 5 is formed in the aspheric lens by enclosing an outer periphery of an aspheric surface 3 formed in the optical function surface area S1. The connecting surface 5 is formed into an arc-shape concave at an optical axis section, and its outer periphery side is enclosed by an edge portion 6. The slope of each surface is matched and set in a smoothly connected continuous shape on a connecting portion of an outer periphery of the aspheric surface 3 and an inner periphery of the connecting surface 5.

Description

Aspheric lens, measuring method thereof and photography module

The present invention relates to an aspheric lens that can be used in various optical systems such as an imaging system or an illumination system, and a method of measuring the same, and a photographic module using the same.

In a variety of recent optical systems, aspherical lenses are used more frequently. For example, in a photographic optical system of a digital camera incorporated in a mobile phone, not only compaction and weight reduction are required, but also an increase in the number of pixels together with an image sensor is required. And have high resolution. According to this case, an aspherical lens is used so that the number of sheets of the lens used can be suppressed, and the aberration can be effectively improved.

The aspherical lens is practically used in any of a glass lens and a plastic lens, and is usually produced by injection molding or press molding using a molding die. Further, since the surface shape of the aspherical lens is greatly affected by the processing accuracy of the transfer surface of the molding die, the aspherical shape of the formed sample is evaluated during the processing of the mold, and one side The evaluation results are fed back to the mold processing, and the processing is performed on the one hand.

It is known that the optical performance of the aspherical lens is largely deteriorated in the case where the accuracy of the aspherical shape itself is greater than that of the aspherical optical axis. As an example, a plastic lens 10 produced by injection molding using a thermoplastic plastic is shown in FIG. The plastic lens 10 is a plano-convex lens in which the upper optical surface is the aspherical surface 10a and the lower optical surface is the flat surface 10b, and the outer periphery is formed integrally with the shape surrounded by the edge portion 11. The plane 10b is obtained as a normal surface, but the aspherical surface 10a is eccentric with respect to a suitable aspherical surface indicated by a two-dot chain line.

As can be seen from the comparison with the optical axis 12s in the normal case, the optical axis 12a of the aspherical surface 10a is shifted (laterally shifted) in parallel to the left to be eccentric, and tilted and tilted. The plastic lens 10 is usually assembled to the lens barrel or the lens frame by the upper and lower surfaces or the outer peripheral surface constituting the edge portion 11. Therefore, if the optical axis is eccentric or tilted, the optical performance is significantly impaired. Therefore, in the processing of the mold, the relative positional relationship between the transfer surface of the edge portion and the transfer surface of the optical surface is strictly managed, and the measurement and evaluation process of the formed sample becomes important.

The aspherical shape can be optically evaluated by an interferometer, but it is difficult to feed back the mold processing as described above for qualitative and relative evaluation. Therefore, a step is performed in which the aspherical shape is measured and evaluated as a quantitative data. The method known in Patent Document 1 is based on the shape data of an aspherical shape obtained by measurement, and the inclination of the optical axis of the aspherical surface and the optical axis is explored by a well-known method of attenuation least squares. Then, after the adjustment of the shape data corresponding to the inclination angle of the obtained aspherical axis is performed and the basic parameter is specified, the regression curve is calculated based on the aspherical equation, and the measured shape data is expressed as the distance. Normalized into a linear regression curve deviation. Further, Patent Document 2 indicates that there is In the case where the evaluation of the inclination of the spherical lens is difficult, the shape error with respect to the spherical surface is added to the peripheral portion of the optical surface to facilitate the tilt detection of the spherical lens.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 2885422

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-85765

In the method of Patent Document 1, as a premise for quantitatively evaluating the aspherical shape, it is assumed that the axis of the aspherical shape and the inclination of the axis are explored. However, when the shape of the aspherical surface is larger than the spherical surface, the shape of the spherical surface is approximately the same, and as described in Patent Document 2, the exploration of the shaft itself is extremely difficult. In particular, in the case of an ultra-small imaging optical system for a mobile phone, since high-precision measurement results are required to be fed back to each lens, the method of Patent Document 1 cannot be applied because of a large error even if it can be detected.

Further, Patent Document 2 is for the purpose of measuring the eccentricity of the spherical lens, and the outer peripheral portion of the spherical lens is replaced with an aspherical surface to improve the detection accuracy of the inclination of the spherical lens. In order to improve the detection accuracy, it is necessary to increase the aspherical shape of the amount of deviation from the spherical surface. On the other hand, in order to maintain the optical performance of the spherical lens, the amount of error superimposed on the optical surface is suppressed to 0.05 μm or less. The effect of setting the optical functional surface to an aspherical surface in order to measure the eccentricity or tilting was obtained.

The present invention has been completed in consideration of the above, and an object thereof is to provide an The aspherical lens having a unique shape is easily and accurately measured, and an object of the present invention is to provide a method for measuring the aspherical lens and a photographing module including the aspherical lens.

In order to achieve the above object, the aspherical lens of the present invention has an optical functional surface in which at least one surface is formed with a lens function of condensing or diverging incident light, and the optical functional surface is integrated with an edge portion surrounding the outer periphery thereof. The shape of the spherical lens is constructed as follows. In other words, the shape of the optical axis cross section of the aspherical lens is formed at a boundary between the outer peripheral edge and the edge portion of the optical functional surface, and a connecting surface that is curved with irregularities opposite to the aspherical surface is formed, and the connecting surface and the outer periphery of the optical functional surface are formed. The edge is smooth and continuous without a step, and the opposite side of the outer peripheral side that is in contact with the edge portion with respect to a plane perpendicular to the optical axis and the inner peripheral side that is continuous with the outer peripheral edge of the optical functional surface The inclination of the plane perpendicular to the optical axis is reversed, and has an inflection point on the joint surface. Here, the inflection point is a point on the connection surface when the plane perpendicular to the optical axis is in contact with the connection surface in the optical axis cross section. Further, the optical axis cross section is a cross section showing a plane including the optical axis of the lens and being cut by a plane parallel to the optical axis.

The optical functional surface itself may be a spherical surface or an aspherical surface, and the connecting surface may be a continuous shape connected to the optical functional surface. As the optical axis cross-sectional shape, for example, an arc connected to the optical functional surface may be used. Shape and so on. Further, when the aspherical surface representing the optical functional surface itself has a shape having an inflection point on the outer side of the region serving as the effective diameter, the aspherical surface connected to the outer diameter of the effective diameter may be directly used as the joint surface. Further, when the optical functional surface is formed of a convex surface, the connection surface is preferably a groove formed by connecting an optical functional surface and an edge portion in a ring shape. When the optical functional surface is formed by a concave surface, the connecting surface is preferably formed between the optical functional surface and the edge portion. A rib that is connected in a ring shape. The aspherical lens having this unique shape can be utilized for at least one of the photographic optical systems used in the photographic module.

The measuring method using the aspherical lens of the present invention has the following steps: a first step of making the apex of the optical functional surface coincide with the origin of the x-axis orthogonal to the optical axis, thereby measuring the optical axis direction along the x-axis The amount of displacement of the upper optical functional surface and the connection surface; and the second step, and then the optical function is evaluated using the overall shape evaluation formula including the polynomial based on the displacement amount of the optical functional surface and the connection surface measured in the first step. The eccentricity and the tilt of the surface and the joint surface, wherein the polynomial represents an aspherical shape in which the optical functional surface and the joint surface are continuous in the cross-sectional shape of the optical axis including the optical axis.

Further, the offset correction step may be combined, and the amount of the eccentricity and the amount of the tilt obtained in the second step is obtained as the offset amount of the design value derived from the overall shape evaluation formula, thereby The measurement data of the optical functional surface measured in the first step is corrected based on the previously obtained offset amount; and the measurement data of the optical functional surface corrected in the offset correction step, and the optical functional surface including the polynomial The design values derived from the shape evaluation formula are compared to evaluate the aspherical shape of the optical functional surface, wherein the polynomial only indicates the shape of the optical functional surface.

The aspherical lens of the present invention is an outer peripheral edge of an optical functional surface obtained by a basic optical design, and is provided with a connecting surface having a unique deviation in contact with the optical functional surface. Therefore, in addition to the optical functional surface evaluation formula which is an evaluation criterion of the surface shape of the optical functional surface of the optical design which has been used in the past, it is possible to define the connection surface from the optical functional surface to the outer periphery of the optical functional surface. The overall shape evaluation formula of the entire shape is therefore expressed by the first shape evaluation formula. In the case where the surface shape is an aspherical surface having a spherical shape, the outer peripheral portion can be configured to have an inflection point, and the eccentricity and the tilt of the lens can be separated by using an overall shape evaluation formula that largely deviates from the spherical surface.

2, 20, 30‧ ‧ lens

2a, 12a, 12s, 20a‧‧‧ optical axis

3, 10a, 21, 31, 32‧‧‧ aspherical

4, 10b‧‧‧ plane

5, 22, 33, 34, 50b, 52a, 53a, 53b‧‧‧ connection surface

6, 11‧‧‧ edge

6a‧‧‧1st edge face

6b‧‧‧2nd edge surface

6c‧‧‧ edge side

10‧‧‧Measurer

12‧‧‧Data processing device

12a‧‧‧Measurement Data Processing Department

12b‧‧‧Shape Evaluation Department

12c‧‧‧ eccentric evaluation department

14‧‧‧Output Department

45‧‧‧Photography module

46‧‧‧Image sensor

47‧‧‧Substrate

48‧‧‧ lens unit

49‧‧‧Mirror tube

50‧‧‧1st lens

50a‧‧‧Optical functional surface

51‧‧‧2nd lens

52‧‧‧3rd lens

53‧‧‧4th lens

55‧‧‧Binder

C1‧‧‧Connecting Department

C2‧‧‧Connecting Department

C3‧‧‧recurve point

Vertex of Q‧‧‧

R‧‧‧ Radius

S1, S21‧‧‧ optical functional area

S2, S22‧‧‧ eccentric evaluation area

Θ1, θ2‧‧‧ slope

X‧‧‧ axis

Z‧‧‧ coordinate value

Fig. 1 is a cross-sectional view showing an optical axis according to an embodiment of the present invention.

Fig. 2 is an explanatory view showing a fitting of a shape evaluation formula and a design shape in a schematic manner.

3 is an explanatory view showing an example of a measurement method of a lens shape.

4 is an explanatory view showing an example of a curve shape data of an aspherical surface.

Fig. 5 is an explanatory view showing an inflection point and a inclination in a joint surface;

Fig. 6 is a cross-sectional view showing an optical axis according to another embodiment of the present invention.

Fig. 7 is a cross-sectional view showing an optical axis according to still another embodiment of the present invention.

Fig. 8 is a schematic optical axis cross-sectional view showing an example of a photographing module to which the present invention is applied.

Fig. 9 is an explanatory view showing an eccentricity of a lens surface;

In Fig. 1 showing an embodiment of the present invention, the lens 2 is produced by injection molding of a thermoplastic plastic, and includes an aspherical surface 3 that is axisymmetric with respect to the optical axis on the first surface side and a flat surface on the second surface side. 4. An annular connecting surface 5 connected along the outer peripheral edge of the aspherical surface 3 and an edge portion 6 on the outer peripheral side of the connecting surface 5. The outer surface of the lens 2 is made by the transfer surface of the forming mold, and the aspherical surface 3, the connecting surface 5, and the plane 4 are optical. The surface finish is an optical functional surface that is required for the lens 2 to exhibit a condensing function for collecting incident light. The optical functional surface of the present embodiment has a condensing function for condensing incident light. However, the present invention is not limited thereto, and the diverging function of divergent incident light may be imparted to the optical functional surface in accordance with desired optical characteristics.

Further, the first edge surface 6a, the second edge surface 6b, and the outer peripheral edge side surface 6c forming the edge portion 6 are used for positioning standards when the lens 2 is assembled to the lens barrel or the lens frame. Therefore, the forming position of the aspherical surface 3 or the flat surface 4 with respect to the edge portion 6 is also strictly controlled. The molding die is produced with high precision by numerical control (NC) processing, but the molded sample is actually ejected as needed, and the shape thereof is confirmed. In the lens 2, in particular, the aspherical surface 3 has a large influence on the condensing function of the lens 2. Therefore, it is required to feed back the eccentric amount to the processing as long as the eccentricity of the aspherical surface 3 with respect to the edge portion 6 can be measured. The process, and in the future processing intensified efforts to make the zero-core.

In order to feed back the measurement result of the lens to the mold, it is necessary to accurately measure the shape of the evaluation lens. In the lens 2 shown in FIG. 1 of the present invention, an optical functional surface shape evaluation formula (hereinafter referred to as a first shape evaluation formula) and an overall shape evaluation formula (hereinafter referred to as the evaluation criteria) of the shape measurement result of the lens are used. 2 shape evaluation formula). The first shape evaluation formula is a polynomial indicating a design shape of the optical function surface region S1 given by the design result of the optical design of the previous lens, and generally uses an aspherical shape formula and is used for evaluation of reproducibility of the aspherical shape.

The second shape evaluation formula is a polynomial that integrally shows the region of the first shape evaluation formula and the design shape of the eccentricity evaluation region S2 including the curved connection surface provided on the outer periphery of the optical function surface. The polynomial of the second shape evaluation formula can be used in the same manner as the first shape evaluation formula as long as it is a shape that is symmetrical with respect to the optical axis. The aspherical shape is also used, and a unique polynomial can also be used.

The polynomial parameter of the second shape evaluation formula is a method of expressing the design shape of the optical functional surface region S1 and the curved connection surface of the outer periphery of the optical functional surface region S1 by one equation, and fitting by a least square method or the like. The process calculates each coefficient. The fitting error at this time need not be 0, but it is desirable to suppress it to 0.5 μ or less.

In Fig. 2, which shows the fitting of the second shape evaluation formula, the dot arrangement in the figure is the optical axis cross-sectional shape of the lens included in the eccentricity evaluation region S2 including the optical axis. The coordinate representation corresponding to the design shape. Further, the polynomial parameter of the second shape evaluation formula is obtained by fitting the coordinates of each point included in the entire eccentricity evaluation region S2. Furthermore, the arrangement of dots in the figure is spaced apart in a schematic manner, but in practice a denser dot arrangement is used in order to achieve a particular precision.

In FIG. 2, the shape of the optical functional surface region S1 in the aspherical surface of the entire eccentricity evaluation region S2 indicated by the dot arrangement is an aspherical surface represented by the first shape evaluation formula, and the shape of the outer connecting surface 5 is a radius. It is an arc of R. In the case where the shape of the aspherical surface indicated by the first shape evaluation formula is extended to the portion deviated from the optical functional surface region S1, the shape of the connecting surface 5 does not coincide with the shape of the connecting surface 5 as indicated by the two-dot chain line P1 in the figure. . In addition, the shape indicated by the second shape evaluation formula after fitting is substantially the same as the majority of the optical function surface area S1 as indicated by the broken line P2, but slightly offset from the design shape on the outer edge side.

Next, a method of measuring the specificity and shape evaluation of the lens 2 obtained by the molding will be described. In order to measure the eccentricity of the aspherical surface 3, the measuring device 10 which measures the surface shape with a light contact or the aspherical surface 3 as shown in FIG. At the time of measurement, the measuring device 10 and the lens 2 are scanned in the x-axis direction so that the shape data of the aspherical surface 3 can be taken. The obtained measurement data is input to the micro-electricity A data processing device 12 composed of a brain. The data processing device 12 is composed of a measurement data processing unit 12a, a shape evaluation unit 12b, and an eccentricity evaluation unit 12c, and the output unit 14 displays or prints various kinds of information obtained by the data processing device 12.

The measurement data processing unit 12a reads the measurement data from the aspheric surface 3 obtained by the measuring device 10 in association with the x coordinate of the measuring device 10. Further, in order to change the azimuth angle with respect to the x-axis of the lens 2, when the lens 2 is rotated about the virtual optical axis, the rotation angle information is also read. In the measurement data obtained from the measuring device 10, noise caused by various factors is superimposed on each measurement point, so that the noise component such as a low pass filter is reduced. In order to find the profile of the aspherical surface. Based on the distribution obtained in this way, the eccentricity evaluation unit 12c evaluates the eccentricity of the aspherical surface 3, and transmits information indicating the evaluation result to the output unit 14.

The eccentricity evaluation unit 12c refers to the second shape evaluation formula and the distribution obtained based on the measurement result, and on the other hand, gives the eccentricity parameter of the parallel eccentricity to the whole and the change of the tilting parameter which gives the inclination, and on the other hand, the least square method is used. The fitting process is performed to obtain the eccentric amount and the amount of tilt of the measurement distribution.

Then, the shape evaluation unit 12b obtains the amount of eccentricity and the amount of tilt obtained by the eccentricity evaluation unit 12c, and obtains the amount of shift between the measurement distribution of the coordinate conversion and the first shape evaluation formula as the machining error. Thereby, the difference between the design shape of the aspherical surface 3 and the measured shape under the condition that the corrected lens 2 is tilted or tilted can be accurately evaluated.

In the evaluation system, the connection surface 5 is included in the second shape evaluation formula for determining the eccentricity and the tilting, and the shape of the optical shape of the second functional evaluation formula is largely different depending on the shape of the optical functional portion. Therefore, evaluation results regarding less eccentricity and dumping error are obtained. In this way, the repair of the mold can be accurately distinguished. The positive object is an eccentric or tilted, or aspherical shape of the optical functional portion. Further, the joint surface 5 is formed by being previously provided on the transfer surface of the molding die, and is not related to the optical function originally required for the lens 2.

As shown in FIGS. 1 and 3, an aspherical surface 3 is formed in the optical functional surface region S1 of the lens 2, and the connecting surface 5 is formed in an annular shape on the outer side. Regarding the shape of the aspherical surface 3, if Z is a coordinate value orthogonal to the x-axis of the optical axis 2a, R is a radius of curvature of an approximate curved surface passing through the vertex Q of the aspherical surface, and k is set to a conic constant ( For the constant of the cone, the aspherical shape using the high order term up to 20 times can usually be represented by the following aspherical shape.

Table 1 shows an example of the specificity of various parameters of the aspherical surface 3, and Table 2 shows the shape data of the aspherical surface specified by the various parameters of Table 1. Further, since the aspherical surface 3 has an axisymmetric shape with respect to the optical axis passing through the vertex Q, the shape data shown in Table 2 indicates the negative side of the x-axis to the vertex Q of the aspherical surface in order to avoid complication.

The aspherical shape shown in Table 1 and Table 2 indicates the opticals shown in Fig. 1. The aspherical shape obtained by the normal optical design of the shape of the functional surface region S1, the aspherical surface shape (1) when the values of the respective parameters and the aspherical coefficients shown in Table 1 are applied are equivalent to the first Shape evaluation formula.

On the other hand, Table 3 below shows the following parameters and aspherical coefficients, which indicate that the aspherical surface 3 fitted in the optical functional surface region S1 shown in Fig. 1 by the aspherical surface shape (1) is increased in the connecting surface 5 The formed eccentricity evaluates the aspherical shape obtained in the case of the overall design shape of the region S2. In addition, when the various parameters and aspherical coefficients shown in Table 3 are applied, the aspherical surface shape (1) corresponds to a second shape evaluation formula that is effective in the evaluation of the eccentricity and the tilting.

Table 4 shows the shape data of the aspheric surface obtained by applying the parameters of Table 3 and the aspherical coefficient to the second shape evaluation formula of the aspherical shape formula (1). In addition, the shape data of the lens of Table 4 shows the negative side of the x-axis to the vertex Q as in Table 2. For the sake of comparison, the vertical line in the beginning of Table 4 indicates the cross-sectional shape of the optical axis of the connection surface. As an example, the shape data can be curved as shown in FIG. 4 to show a rough shape. Further, the broken line indicates an extended portion of the aspherical shape appearing on the outer side of the eccentricity evaluation region S2.

For example, the shape information and the profit of Table 2 obtained by the first shape evaluation formula Comparing the shape data of Table 4 obtained by the second shape evaluation formula, it is understood that there are slight differences between the two aspherical surfaces based on the values of the various parameters of Tables 1 and 3 and the aspherical coefficients. This difference is caused by the fact that the original aspheric surface 3 increases the joint surface 5. The first shape evaluation formula is an evaluation formula for evaluating the shape of the aspherical surface 3 itself, and the shape of the aspherical surface obtained by the first shape evaluation formula completely coincides with the shape of the aspherical surface in the optical functional surface region S1.

On the other hand, the evaluation purpose of the second shape evaluation formula is not limited to the evaluation of the eccentricity and the tilting, and therefore the error within the allowable range in the optical functional surface region S1 has no effect. Further, as shown in FIG. 3, when the measurement data obtained from the measuring device 10 is considered to overlap the noise of several μm or more, even if the aspherical surface 3 is evaluated by the shape data of Table 4, the aspherical surface 3 is not greatly affected. As a result of the eccentricity evaluation, the processing of removing the noise component by the self-measurement data and the fitting of the shape data considering the aspherical surface can be obtained, and the distribution as shown in FIG. 3 can be obtained.

When the connection surface 5 is a part of the aspherical surface connected to the aspherical surface 3 and the shape is evaluated by the data processing device 12 based on the measurement data from the measuring device 10, and the eccentricity evaluation is performed, the non-confirmation is confirmed. The accuracy of the eccentric evaluation of the spherical surface 3 is remarkably improved. Table 5 below is an eccentricity evaluation result of the aspherical shape data (Table 2) based on the standard design specified by the parameters of Table 1, and an aspherical surface designed based on the evaluation specific to the parameters of Table 3. The eccentricity evaluation results of the shape data (Table 4) were summarized. Further, as for the aspherical shape data, as shown in FIG. 3, not only the shape data of the negative side of the x-axis but also the shape data of the positive side of the x-axis of the vertex Q of the aspherical surface is used.

Table 5 shows the results of repeating the measurement five times in the same manner as shown in Fig. 3, and obtaining the parallel deviation in the x-axis direction corresponding to the optical axis 2a by the data processing device 12 at a time. The result of the amount of eccentricity moved (μm) and the angle of tilting (minutes). In the prior art, the eccentricity and the tilt angle β are obtained based on the measurement data in the range of the optical functional surface region S1, and the eccentricity is obtained in the same manner based on the measurement data of the range of the eccentricity evaluation region S2. With the amount of dumping. Further, the average value of each calculation result, and the magnitude (variation range) of the minimum value and the maximum value are shown. It is apparent that the shape evaluation and the eccentricity evaluation by the aspect of the present invention including the joint surface 5 can detect the eccentric amount and the amount of tilt of the optical axis of the aspherical surface with high precision.

As described above, the front lens in which the joint surface 5 is not formed is such that the outer circumference of the aspherical surface 3 of FIG. 1 is surrounded by the edge portion 6, and data processing is performed based on the measurement data of the aspheric surface obtained from the optical functional surface region S1. Then, the aspherical shape obtained by shape evaluation by fitting or the like is evaluated based only on the shape data of the aspherical surface 3 in the range of the optical functional surface region S1. Therefore, when the aspherical surface 3 is a shape that particularly approximates a spherical surface, The reliability of the eccentric evaluation is significantly reduced.

In contrast, the present invention is connected to the outer periphery of the aspherical surface 3 of Fig. 1. In the meantime, the arc-shaped connecting surface 5 is connected to the optical axis section, and the lens 2 including the eccentricity evaluation region S2 including the connecting surface 5 as a new aspherical surface is formed. On the other hand, the aspherical surface of the entire eccentricity evaluation region S2 including the joint surface 5 is redefined by the aspherical shape formula (1), and the aspherical shape data of the optical design is obtained. In addition, when the actual shape of the lens 2 is evaluated, the distribution of the entire eccentricity evaluation region S2 obtained by performing data processing and fitting on the measurement data obtained from the measuring device 10 becomes an aspherical shape having a large difference from the spherical surface. Therefore, even if the aspherical surface 3 in the optical functional surface region S1 is approximately spherical, the reliability of the eccentricity evaluation is greatly improved with respect to the aspherical surface of the entire eccentricity evaluation region S2, for example, feedback is made during the processing of the forming mold. The evaluation results can be effectively used for adjustment data during NC processing.

Further, the aspherical surface of the eccentricity evaluation region S2 is an aspherical surface in which the aspherical surface 3 of the optical functional surface region S1 is increased by the connection surface 5, and thus the optical functional surface region S1 obtained by optical design may be obtained. The shape of the aspheric inside is affected. In order to prevent this, it is effective that the connecting surface 5 itself is smoothly continuous in such a manner that irregularities are not generated at the boundary between the aspherical surface 3 and the connecting surface 5, and the optical axis cross-sectional shape of the connecting surface 5 itself is not excessively widened. It is also set to a simple curved shape such as an arc shape or a sinusoidal curve.

In FIG. 5 in which the connecting surface 5 is enlarged, the arc-shaped connecting surface 5 is connected to the outer peripheral side of the aspherical surface 3 so as to be continuous without a step on the inner peripheral side of the connecting portion C1, and on the outer peripheral side. It is connected to the first edge surface 6a perpendicular to the optical axis 2a by the connecting portion C2. The connecting surface 5 includes an inflection point C3, and the tangent to the connecting surface 5 at the inflection point C3 is perpendicular to the optical axis 2a similarly to the first edge surface 6a. The connection surface 5 includes the above-described inflection point C3, whereby the inclination θ1 of the tangent of the connection portion C1 of the connection surface 5 and the inclination θ2 of the tangent to the connection portion C2 are reversed.

As described above, since the connecting surface 5 is used for evaluating the eccentricity and the tilting, and is not used optically, the entire connecting surface 5 or the outer portion of the inflection point C3 is not necessarily fine. Processed into an optical surface. Therefore, if the shape of the shape shown in FIG. 3 is not large, and the amount of unevenness is, for example, 1 μ or less, preferably 0.5 μm or less, it is possible to reduce the amount of harmful light by roughening the surface. The flare or ghost caused by the reflection.

FIG. 6 shows the lens 20 in which the concave aspheric surface 21 is formed on the first surface, and the second surface is the flat surface 4 as in the previous embodiment. A connecting surface 22 is continuously formed on the outer peripheral edge of the concave aspheric surface 21, and the outer peripheral edge of the connecting surface 22 coincides with the inclination of the surface at the boundary with the outer peripheral edge of the concave aspherical surface 20. The connecting surface 22 has an arc shape in cross section of the optical axis, and the concave aspheric surface 21 is surrounded by an annular shape as a whole. The edge portion 6 is integrally formed on the outer circumference of the joint surface 22 in the same manner as in the previous embodiment, and the first edge surface 6a and the second edge surface 6b of the edge portion 6 are planes orthogonal to the optical axis 20a, and the edge side surface 6c is A circumferential surface parallel to the optical axis 20a. The present invention can also be applied to the lens 20 in exactly the same manner as in the previous embodiment.

In Fig. 7 showing another embodiment, the lens 30 has a convex aspherical surface 31 similar to that of the first embodiment, and a concave aspherical surface 32 of the second surface which is the same as the concave aspherical surface 32 of the second embodiment. Meniscus lens. An annular connecting surface 33 that is recessed in an arc shape in the optical axis cross section is formed on the outer peripheral edge of the convex aspheric surface 31, and a circular cross section is formed on the outer peripheral edge of the concave aspheric surface 32. An arcuate annular connecting surface 34. Further, the outer peripheral edge of the aspherical surface 31 and the inner peripheral edge of the joint surface 33 are continuously connected without any step, and the outer peripheral edge of the aspherical surface 32 and the inner peripheral edge of the joint surface 34 are continuously connected without any difference, and also The previous embodiment is the same.

Further, the aspherical surfaces 31 and 32 of the lens 30 are sequentially evaluated on one side, and the convex aspheric surface 31 is formed based on the first shape in the range of the optical functional surface region S1 as in the above-described embodiment. In the evaluation of the evaluation formula, the eccentricity and the tilting of the aspherical surface 31 were evaluated by the second shape evaluation formula in the eccentricity evaluation region S2 including the joint surface 33. In the same manner, in the concave aspheric surface 32, the shape of the aspherical surface 32 is evaluated by the first shape evaluation formula in the optical functional surface region S21, and the second shape evaluation is performed in the eccentricity evaluation region S22 including the connection surface 34. The evaluation of eccentricity and pouring was performed.

FIG. 8 shows an example of a photographing module built in a mobile phone. The photographic module 45 is formed by fixing a lens unit 48 to a substrate 47 on which, for example, a complementary metal oxide semiconductor (CMOS) type image sensor 46 is mounted. In the lens unit 48, the first lens 50, the second lens 51, the third lens 52, and the fourth lens 53 are assembled to the lens barrel 49, and the number of lenses can be appropriately increased or decreased according to the optical design.

The first lens 50 fixed to the upper surface of the lens barrel 49 is produced by injection molding of a thermoplastic plastic. The first lens 50 is an aspherical lens described in the previous embodiment, and an annular connecting surface formed by a concave curved surface is provided on the outer periphery of the optical functional surface 50a formed of a convex aspherical surface. 50b. Further, the evaluation of the eccentricity or the tilting can be performed by applying the second shape evaluation formula to the entire connection surface 50b.

The second lens 51, the third lens 52, and the fourth lens 53 are sequentially assembled from the lower side of the lens barrel 49, and after the fourth lens 53 is finally assembled, it is fixed to the photocurable adhesive 55 as shown in the figure. The lens barrel 49. At this time, the second lens 51, the third lens 52, and the fourth lens 53 are fitted to the inner wall of the lens barrel 49 to be positioned in the radial direction. The optical axis direction is positioned on the edge surface of each lens. Further, between the lens barrel 49 and the second lens 51, between the second lens 51 and the third lens 52, and further between the third lens 52 and the fourth lens 53, the harmful light is blocked to reduce the ghost image or A flashing blackout ring. Further, not only the first lens 50 but also the third lens 52 and the fourth lens 53 may be provided with connection faces 52a, 53a, 53b surrounding the optical function surface as illustrated. In this case, as described above, the outer surface of the inflection point of each of the connecting surfaces is a rough surface having irregularities of 1 μ or less, preferably 0.5 μ or less. It is advantageous that the harmful light incident into the optical system is attenuated to suppress the generation of flash or ghost image.

The subject light incident on the optical function surface 50a of the first lens 50 is imaged on the imaging surface of the image sensor 46 by the second lens 51, the third lens 52, and the fourth lens 53 after the first lens 50. Thereby taking pictures. The photographic module 45 uses a fixed focus photographic optical system, but it is also possible to assemble a part of the lens in such a manner as to be movable in the direction of the optical axis, so as to have a focus or zoom function, and thus a part of the lens can be The optical axis moves vertically in the plane to have a hand vibration correction function.

As described above, the present invention has been described with respect to the embodiment shown in the drawings. The present invention is directed to the outer peripheral edge continuous connection surface of the aspherical lens, and the aspherical surface of the aspherical surface can be measured with high precision. By applying to a molded lens using plastic or glass, it can be effectively used for performing lens forming with higher precision. Further, when the outer peripheral edge of the spherical lens is continuously curved in the same manner and aspherical as a whole, the accuracy of the eccentricity measurement on the spherical surface can be improved.

2‧‧‧ lens

2a‧‧‧ optical axis

3‧‧‧Aspherical

4‧‧‧ plane

5‧‧‧ Connection surface

6‧‧‧Edge

6a‧‧‧1st edge face

6b‧‧‧2nd edge surface

6c‧‧‧ edge side

S1‧‧‧Optical functional area

S2‧‧‧ eccentric evaluation area

Claims (14)

An aspherical lens, wherein the aspherical lens is an optical functional surface on which at least one surface is formed with condensed or divergent incident light, and the optical functional surface is integrally formed with an edge portion surrounding the optical functional surface, and is characterized in that a shape including a cross section of an optical axis of a cross section of the lens that is cut by a plane parallel to the optical axis, and a connection surface at a boundary between an outer peripheral edge of the optical functional surface and the edge portion, wherein the connection surface is The aspherical surface is formed on the optical functional surface, and the outer peripheral edge of the optical functional surface is formed by a continuous surface that is smoothly connected to the connecting surface, and the connecting surface is in contact with the optical functional surface on the inner peripheral side. The region between the connecting portion and the boundary portion of the edge portion on the outer peripheral side has a surface parallel to a plane perpendicular to the optical axis. The aspherical lens according to claim 1, wherein the optical functional surface is aspherical. The aspherical lens according to claim 2, wherein the connecting surface is a general aspherical surface connected to the optical functional surface. The aspherical lens according to claim 1 or 2, wherein the optical functional surface is a convex surface, and the connecting surface has a groove formed in an annular shape between the optical functional surface and the edge portion. The aspherical lens according to claim 3, wherein the optical functional surface is a convex surface, and the connecting surface has a groove connected in an annular shape between the optical functional surface and the edge portion. An aspherical lens as described in claim 1 or 2, wherein The optical functional surface is a concave surface, and the connecting surface has a ridge formed in a ring shape between the optical functional surface and the edge portion. The aspherical lens according to claim 3, wherein the optical functional surface is a concave surface, and the connecting surface has a rib formed in a ring shape between the optical functional surface and the edge portion. The aspherical lens according to claim 4, wherein the shape of the optical axis cross section of the connecting surface is an arc shape. The aspherical lens according to claim 5, wherein the shape of the optical axis cross section of the connecting surface is an arc shape. The aspherical lens according to claim 6, wherein the shape of the optical axis cross section of the connecting surface is an arc shape. The aspherical lens according to claim 7, wherein the shape of the optical axis cross section of the connecting surface is an arc shape. The method for measuring an aspherical lens is the method for measuring an aspherical lens according to the first or second aspect of the invention, and has the following steps: the first step of making the apex of the optical functional surface orthogonal to The origin of the x-axis of the optical axis coincides with each other, and the amount of displacement of the optical functional surface and the connecting surface in the optical axis direction is measured along the x-axis; and the second step is based on the optical function measured in the first step. An amount of displacement of the surface and the connecting surface is used to evaluate an eccentricity of the optical functional surface and the connecting surface in the optical axis cross section and an optical axis with respect to the optical axis by using an overall shape evaluation formula including a polynomial in the optical axis cross section. Pour, wherein the polynomial represents a shape in which the optical functional surface is continuous with the connecting surface. The method for measuring an aspherical lens according to claim 12, The offset correction step is performed in the second step, wherein the eccentricity and the amount of the tilt are obtained as an offset from a design value derived from the overall shape evaluation formula, and based on the offset And measuring the measurement data of the optical functional surface measured in the first step; and measuring the optical functional surface corrected in the offset correction step, and evaluating the optical functional surface shape including the polynomial The design values derived from the equation are compared to evaluate the aspherical shape of the optical functional surface, wherein the polynomial only represents the shape of the optical functional surface. A photographic module having at least one aspherical lens as described in claim 1 or 2.