Optical device

Abstract

Provided is an optical device for irradiating an image sensor with inspection light 10, wherein the angle of the inspection light is made controllable to a predetermined characteristic, especially in a region with high image height.　In the optical device, diffused light passes through an aperture 19 of a diaphragm and one lens 23 to become the inspection light 10, with which an image sensor 8 is irradiated. In an incident surface 23A of the lens 23, an input field of view (a region having a radius r from zero to R1) contributing to the generation of the inspection light 10 has positive optical power across the whole region. In an emission surface 23B, an output field of view (a region having the radius r from zero to R2) contributing to the generation of the inspection light 10 has negative optical power in a circular first region close to the optical axis, and has positive optical power in an annular second region farther from the optical axis than the first region.

Description

Optical device

[0001] The present invention relates mainly to an optical device for irradiating inspection light onto the light-receiving surface of a solid-state imaging device (image sensor) such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

[0002] One such optical system is disclosed in Patent Document 1. The optical system described in Patent Document 1 has a single aspherical lens between the aperture stop and the irradiation position. Inspection light having a predetermined CRA (chief ray angle) characteristic is irradiated from this aspherical lens onto the irradiation position (corresponding to the light-receiving surface of the image sensor). As the above-mentioned predetermined CRA characteristic, for example, one is disclosed in which the CRA increases approximately in a saturation curve manner as the image height increases.

[0003] Japanese Patent Application Laid-Open No. 2022-145349

[0004] In the inspection of an image sensor, the incident angle tends to increase as the image height increases. In particular, in a region with a relatively high image height, there is a requirement not to increase the incident angle of the inspection light too much (that is, to more strongly suppress the increase in the incident angle).

[0005] Also, in a region with a relatively high image height, in order to ensure a certain amount of input light to the image sensor, there is a requirement to ensure a certain magnitude of the angular difference between the CRA and the upper ray angle, and the angular difference between the CRA and the lower ray angle.

[0006] From the viewpoint of manufacturing cost, it is more desirable if the above requirements can be satisfied with a simple configuration having only one lens.

[0007] One object is to enable the angle of inspection light to be controlled to a predetermined characteristic in an optical device, particularly in a region with a high image height.

[0008] Another object will become apparent from the following disclosure.

[0009] An optical device for irradiating the light-receiving surface of an image sensor with inspection light, according to one embodiment, comprises a single lens having an optical axis, an incident surface, and an exit surface, and an aperture disposed on the incident side of the lens and having an opening at the center through which the optical axis passes, configured such that diffused light passes through the opening and then enters the lens, and the inspection light is emitted from the lens, wherein the incident field of view, which is the region of the incident surface that contributes to the generation of the inspection light, has positive power throughout, and the exit field of view, which is the region of the exit surface that contributes to the generation of the inspection light, has negative power in a circular first region close to the optical axis and positive power in an annular second region further from the optical axis than the first region.

[0010] With respect to the sag of the incident surface and the exit surface of the lens, if we define the incident side as the positive side and the exit side as the negative side along the optical axis from the center point through which the optical axis passes to each surface, and define the radius of the incident field of view as the incident field of view radius and the radius of the exit field of view as the exit field of view radius, then the shape of the lens in the optical apparatus according to one embodiment may be as follows. The sag of the incident surface decreases to the negative side as the radius increases, from zero to a first radius smaller than the incident field of view radius, and then increases within the negative range from the first radius to the incident field of view radius. The sag of the exit surface decreases to the negative side as the radius increases, from zero to a second radius smaller than the exit field of view radius, and then increases from the second radius to a third radius larger than the second radius but smaller than the exit field of view radius, and then transitions from a negative value to a positive value at the third radius and increases to the exit field of view radius.

[0011] An optical device for irradiating the light-receiving surface of an image sensor with inspection light, according to a second embodiment, comprises a single lens having an optical axis, an incident surface, and an exit surface, and an aperture positioned on the incident side of the lens and having an opening at its center through which the optical axis passes, wherein diffused light passes through the opening and then enters the lens, and the inspection light is emitted from the lens, wherein the incident field of view, which is the region of the incident surface that contributes to the generation of the inspection light, has negative power in a circular first region close to the optical axis and positive power in an annular second region further from the optical axis than the first region, and the exit field of view, which is the region of the exit surface that contributes to the generation of the inspection light, has positive power throughout.

[0012] The shape of the lens in the optical apparatus according to the second embodiment may be as follows: The sag of the incident surface remains zero or increases to the positive side as the radius increases from zero to a first radius smaller than the incident field radius, and further increases to the positive side from the first radius to the incident field radius. The sag of the exit surface remains zero or increases to the positive side as the radius increases from zero to a second radius smaller than the exit field radius, and further increases to the positive side from the second radius to the exit field radius.

[0013] An optical device for irradiating the light-receiving surface of an image sensor with inspection light, according to a third embodiment, comprises a single lens having an optical axis, an incident surface, and an exit surface, and an aperture disposed on the incident side of the lens and having an opening at the center through which the optical axis passes, configured such that diffused light passes through the opening and then enters the lens, and the inspection light is emitted from the lens, wherein the incident field of view of the incident surface, which is the region that contributes to the generation of the inspection light, has negative power in a circular first region close to the optical axis and positive power in an annular second region further from the optical axis than the first region, and the exit field of view of the exit surface, which is the region that contributes to the generation of the inspection light, has negative power in a circular third region close to the optical axis and positive power in an annular fourth region further from the optical axis than the third region.

[0014] The shape of the lens in the optical apparatus according to the third embodiment may be as follows: The sag of the incident surface remains at zero or increases to the positive side as the radius increases, from zero to a first radius smaller than the incident field radius, and further increases to the positive side from the first radius to the incident field radius. The sag of the exit surface decreases to the negative side as the radius increases, from zero to a second radius smaller than the exit field radius, then begins to increase from the second radius, increases to a third radius larger than the second radius but smaller than the exit field radius, and then transitions from a negative value to a positive value at the third radius and increases to the exit field radius.

[0015] An optical device according to the fourth embodiment, which includes an aperture having an output port for irradiating the light-receiving surface of an image sensor with inspection light, is configured such that the inspection light from the output port of the aperture is irradiated onto the light-receiving surface of the image sensor, and a shielding wall is provided in front of the output port of the aperture in the direction of emission to block light from the output port toward other image sensors other than the image sensor.

[0016] An optical device for irradiating the light-receiving surface of an image sensor with inspection light, according to the fifth embodiment, comprises a lens system and an aperture having an opening located on the incident side of the lens system, configured such that diffused light passes through the opening and then enters the lens, and the inspection light is emitted from the lens, and a shielding wall is provided in front of the exit direction of the lens system to block light from the lens system toward other image sensors other than the image sensor.

[0017] The cross-sectional shape of the shielding wall may have an aspect ratio corresponding to the aspect ratio of the image sensor.

[0018] Figure 1 shows a longitudinal cross-sectional configuration along the optical axis of the optical device according to the first embodiment. Figure 2 shows a cross-sectional structure along the optical axis of the illumination lens system. Figure 3 shows an example of the relationship between the radius of the lens's incident surface centered on the optical axis and the refractive power (power) of the incident field of view of the incident surface. Figure 4 shows an example of the relationship between the radius of the lens's exit surface centered on the optical axis and the refractive power (power) of the exit field of view of the exit surface. Figure 5 shows an explanatory diagram of the relationship between the sag of the lens's incident surface and the radius. Figure 6 shows an explanatory diagram of the relationship between the sag of the lens's exit surface and the radius. Figure 7 shows an example of the characteristics of CRA, upper ray angle, and lower ray angle at the illumination surface by the optical device according to the first embodiment. Figure 8 shows a cross-sectional structure along the optical axis of the illumination lens system of the optical device according to the second embodiment. Figure 9 shows an example of the relationship between the lens radius and the refractive power (power) of the lens's incident field of view. Figure 10 shows an example of the relationship between the lens radius and the refractive power (power) of the lens's exit field of view. Figure 11 shows an explanatory diagram of the relationship between the sag of the lens's incident surface and the radius. Figure 12 shows an explanatory diagram illustrating the relationship between the sag and radius of the lens's exit surface. Figure 13 shows an example of the CRA characteristics on the illumination surface by the optical device according to the second embodiment. Figure 14 shows a cross-sectional structure along the optical axis of the illumination lens system of the optical device according to the third embodiment. Figure 15 shows an example of the relationship between the radius of the lens and the refractive power (power) of the lens's incident field of view. Figure 16 shows an example of the relationship between the radius of the lens and the refractive power (power) of the lens's exit field of view. Figure 17 shows an explanatory diagram illustrating the relationship between the sag and radius of the lens's incident surface. Figure 18 shows an explanatory diagram illustrating the relationship between the sag and radius of the lens's exit surface. Figure 19 shows an example of the CRA characteristics on the illumination surface by the optical device according to the third embodiment. Figure 20 shows a longitudinal cross-sectional configuration along the optical axis of the optical device according to the fourth embodiment. Figure 21 shows an example of the cross-sectional shape of a shielding wall. Figure 22 shows an example of the cross-sectional shape of a shielding wall. Figure 23 shows an example of the cross-sectional shape of a shielding wall. Figure 24 shows a longitudinal cross-sectional configuration along the optical axis of the optical device according to the fifth embodiment. Figure 25 shows a longitudinal cross-sectional configuration along the optical axis of each optical device in the image sensor inspection apparatus according to the sixth embodiment. Figures 26A and 26B show variations of the plan view of the light-shielding wall, i.e., the front end portion of the optical device. Figure 27 shows a cross-sectional view along the optical axis of each optical device in the inspection apparatus according to the eighth embodiment.Figure 28 shows a cross-sectional view along the optical axis of each optical device in the inspection apparatus according to the ninth embodiment. Figure 29 shows a cross-sectional view along the optical axis of each optical device in the inspection apparatus according to the tenth embodiment. Figure 30 shows a cross-sectional view along the optical axis of each optical device in the inspection apparatus according to the eleventh embodiment. Figure 31 shows a cross-sectional view along the optical axis of each optical device in the inspection apparatus according to the twelfth embodiment.

[0019] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited by these embodiments. Furthermore, in the drawings, identical parts are denoted by the same reference numerals. While terms such as "first," "second," and "third" may be used in this disclosure to describe various elements or components, it will be understood that these elements or components should not be limited by these terms. These terms are used solely to distinguish one element or component from another. Therefore, the first element or component discussed below may also be called the second element or component without departing from the teaching of the concept of the present invention.

[0020] Figure 1 shows a longitudinal cross-sectional configuration along the optical axis of an optical device according to the first embodiment. The optical device 1 has a hollow cylindrical lens barrel 3. During inspection, the light-receiving surface of one image sensor 8 to be inspected is placed on the illumination surface 7 shown at the right end of the figure. During inspection, an input light beam (e.g., telecentric light) 5 from a light source device (not shown) enters the lens barrel 3 from the left side of the figure, and the light beam is adjusted to an inspection light beam that satisfies certain conditions as it passes through the lens barrel 3 and is irradiated onto the illumination surface 7 (i.e., the light-receiving surface of the image sensor 8). Note that in Figure 1, for illustrative purposes, only the portion of the image sensor 8 corresponding to the light-receiving surface of one of the many image sensors formed on the wafer surface is shown.

[0021] Inside the lens barrel 3, the pre-optical system 11, the aperture diaphragm 17, and the lens 23 are arranged in order from the input side to the output side. The pre-optical system 11 converts the input light beam 5 from the light source into a diffused light beam that diffuses at all positions in the aperture 19 of the aperture diaphragm 17. The specific configuration of the pre-optical system 11 is not shown in the diagram, but there are various variations, and for example, a known or publicly used configuration may be adopted. The diffused light beam that exits the pre-optical system 11 and passes through the aperture 19 is input to the lens 23.

[0022] Figure 2 shows the cross-sectional structure of the illumination lens system along the optical axis. In Figure 2, the straight line on the left represents the aperture 19 of the aperture diaphragm 17, and the straight line on the right represents the illumination surface 7 (on which the light-receiving surface of the image sensor 8 is placed during inspection). Diffuse light enters from the left of the figure, passes through the aperture 19 and lens 23 in sequence, becomes inspection light 10, and reaches the illumination surface 7.

[0023] Lens 23 is a non-imaging type aspherical lens, having, for example, a disc shape or a polygonal plate shape centered on the optical axis 31. In lens 23, the dotted auxiliary line 23C in the figure indicates the outer edge of the effective lens region, and only the lens region inside this line functions as a lens.

[0024] In this specification, a circular region of the illumination surface 7 with a radius equal to the maximum image height Hmax of the image sensor 8 is referred to as the "illumination field" 9, meaning the field of view on the illumination surface 7 that actually contributes to the inspection of the image sensor 8. Furthermore, the region of the incident surface 23A of the lens 23 through which the inspection light 10 irradiated into the illumination field 9 passes (in short, the region of the incident surface 23A that contributes to the generation of the inspection light 10) is referred to as the "incident field," and the radius of this incident field centered on the optical axis 31 is referred to as the "incident field radius" R1. In addition, the region of the exit surface 23B of the lens 23 through which the inspection light 10 irradiated into the illumination field 9 passes (in short, the region of the exit surface 23B that contributes to the generation of the inspection light 10) is referred to as the "exit field," and the radius of the exit field centered on the optical axis 31 is referred to as the "exit field radius" R2. In the description of other embodiments to be discussed later, the terms incident field, incident field radius R1, exit field, and exit field radius R2 are used in the same sense as above.

[0025] Figure 3 shows an example of the relationship between the radius r (see Figure 2) of the incident surface 23A of the lens 23, centered on the optical axis 31, and the refractive power (power) of the incident field of view of the incident surface 23A (i.e., the region from radius r to the incident field of view radius R1). As shown in Figure 3, the power of the incident surface 23A has a positive value throughout the entire incident field of view (i.e., it acts like a convex lens). Furthermore, the power of the incident field of view decreases steplessly (i.e., without steps) as the radius r increases. The rate of decrease in the power of the incident field of view with increasing radius r increases with increasing radius r.

[0026] Figure 4 shows an example of the relationship between the radius r (see Figure 2) of the exit surface 23B of the lens 23 centered on the optical axis 31 and the refractive power (power) of the exit field of view of the exit surface 23B (i.e., the region from radius r zero to the exit field of view radius R2). As shown in Figure 4, the power of the exit surface 23B has a negative value in the region from radius r zero to a first radius R3 smaller than the exit field of view radius R2, and a positive value in the region from the first radius R3 to the exit field of view radius R2. Furthermore, as the radius r increases, the power of this exit field of view increases constantly or steplessly (i.e., without steps) in the negative value region, and also increases steplessly (i.e., without steps) in the positive value region. The rate of increase of the power of the exit field of view as the radius r increases is either increasing as the radius r increases or being partially constant.

[0027] Figure 5 shows an explanatory diagram illustrating the relationship between the sag Z1 and radius r of the incident surface 23A of the lens 23. In the figure, the value of sag Z1 is zero at the center point (optical axis position) through which the optical axis 31 of the incident surface 23A passes, and is positive on the incident side (left side in the figure) and negative on the exit side (right side in the figure).

[0028] As shown in Figure 5, the sag Z1 of the incident field of view of the incident surface 23A (the region from radius r zero to the incident field of view radius R1) decreases to the negative side as the radius r increases, from zero to a second radius R11 which is smaller than the incident field of view radius R1, and then increases within the negative range from the second radius R11 to the incident field of view radius R1. In other words, the incident field of view of the incident surface 23A has a shape in which the peripheral part is concave towards the exit side from the center, or in other words, a shape in which the center bulges towards the incident side from the peripheral part.

[0029] Figure 6 is an explanatory diagram showing the relationship between the sag Z2 and radius r of the exit surface 23B of the lens 23. In the figure, the value of sag Z2 is zero at the center point (optical axis position) through which the optical axis 31 of the exit surface 23B passes, and is positive on the incident side (left side in the figure) and negative on the exit side.

[0030] As shown in Figure 6, the sag Z2 of the exit field of view of the exit surface 23B (the region from radius r zero to exit field of view radius R2) decreases to the negative side as the radius r increases, from zero to a third radius R21 which is smaller than the exit field of view radius R2, and then begins to increase from the third radius R21. Furthermore, as the radius r increases from the third radius R21, the sag Z2 increases to a fourth radius R22 which is larger than the third radius R21 but smaller than the exit field of view radius R2, and then transitions from a negative value to a positive value at the fourth radius R22 and increases to the exit field of view radius R2. In other words, as the radius r increases, the exit field of view of the exit surface 23B has a shape in which the peripheral part bulges outwards from the center towards the exit side, and then slightly indents towards the incident side.

[0031] Figure 7 shows an example of the characteristics of the CRA (principal ray angle), upper ray angle, and lower ray angle at the illumination surface 7 by the optical device according to the first embodiment having the configuration described above. In Figure 7, the solid curves 51, 53, and 55 represent the CRA, upper ray angle, and lower ray angle, respectively, according to the image height h.

[0032] As shown in Figure 7, according to the optical device of this embodiment, by configuring the lens 23 as described above, the increase in CRA 51, the upper ray angle 53, and the lower ray angle 55 with increasing image height h can be appropriately suppressed, and their incident angles 51, 53, and 55 can not be made too large, especially in regions where the image height h is relatively large. Furthermore, even in regions where the image height h is relatively high, the angular difference between CRA 51 and the upper ray angle 53, and the angular difference between CRA 51 and the lower ray angle 55 are large enough to ensure a moderately large amount of light. This performance can be obtained by controlling the diffused light from the aperture diaphragm 17 with only one lens 23, which is also advantageous in terms of manufacturing costs.

[0033] Next, an optical device according to a second embodiment will be described. In the second embodiment, the configuration of the illumination lens system differs from that of the first embodiment, while the configurations of other parts (other than design items that can be appropriately selected or adjusted by those skilled in the art) may be substantially the same as those of the first embodiment. The following description will focus on the lens configuration.

[0034] Figure 8 shows a cross-sectional structure along the optical axis of the illumination lens system of the optical device according to the second embodiment. In Figure 8, the straight line on the left represents the aperture 19 of the aperture diaphragm 17, and the straight line on the right represents the illumination surface 7 (on which the light-receiving surface of the image sensor 8 is placed during inspection). Diffuse light enters from the left of the figure, passes sequentially through the aperture 19 and a single lens 24 to become inspection light 10, and reaches the illumination surface 7.

[0035] The lens 24 is a non-imaging type aspherical lens, having, for example, a disc shape or a polygonal plate shape centered on the optical axis 31. In the lens 24, the dotted auxiliary line 24C in the figure indicates the outer edge of the effective lens area, and only the lens area inside that line functions as a lens. The incident field of view of the lens 24, which is the region from radius r zero to the incident field of view radius R1 on the incident surface 24A, and the exit field of view of the exit surface 24B, which is the region from radius r zero to the exit field of view radius R2, contribute to the generation of inspection light 10 that is irradiated onto the light-receiving surface of the image sensor 8.

[0036] Figure 9 shows an example of the relationship between the radius r of lens 24 and the refractive power (power) of the incident field of view of lens 24. As shown in Figure 9, the power of the incident field of view of lens 24 has a negative value in the region from radius r to a fifth radius R4 which is smaller than the incident field radius R1, and a positive value in the region from the fifth radius R4 to the incident field radius R1. Furthermore, this power increases steplessly (i.e., without steps) as the radius r increases, and the rate of increase also increases or remains partially constant.

[0037] Figure 10 shows an example of the relationship between the radius r of lens 24 and the refractive power (power) of the exit field of view of lens 24. As shown in Figure 10, the power of the exit field of view has a positive value throughout the entire exit field of view. Furthermore, this power increases steplessly (i.e., without steps) as the radius r increases. The rate of increase increases in the region where the radius r is relatively small, and decreases in the region where the radius r is relatively large.

[0038] Figure 11 is an explanatory diagram showing the relationship between the sag Z3 and radius r of the incident surface 24A of the lens 24. In the figure, the value of sag Z3 is zero at the center point (optical axis position) through which the optical axis 31 of the incident surface 24A passes, and is positive on the incident side and negative on the exit side.

[0039] As shown in Figure 11, the sag Z3 of the incident field of view of the incident surface 24A (the region from radius r zero to incident field of view radius R1) remains at zero or increases at a relatively low rate from radius r zero to a sixth radius R31 smaller than the incident field of view radius R1, and then increases at a relatively high rate from the sixth radius R31 to the incident field of view radius R1. In other words, the incident field of view of the incident surface 24A has a shape in which the center is recessed toward the exit side than the peripheral part.

[0040] Figure 12 shows an explanatory diagram of the relationship between the sag Z4 and radius r of the exit surface 24B of the lens 24. In the figure, the value of sag Z4 is zero at the center point (optical axis position) through which the optical axis 31 of the exit surface 24B passes, and is positive on the incident side (left side in the figure) and negative on the exit side.

[0041] As shown in Figure 12, the sag of the exit field of view of the exit surface 24B (the region from radius r zero to exit field of view radius R2) remains zero or increases to the positive side as the radius r increases, from zero to a seventh radius R41 which is smaller than the exit field of view radius R2, and then increases further to the positive side from the seventh radius R41 to the exit field of view radius R2. In other words, the exit field of view of the exit surface 24B has a shape in which the center bulges outwards toward the exit side compared to the peripheral part.

[0042] Figure 13 shows an example of the characteristics of the CRA on the irradiation surface 7 by the optical device according to the second embodiment having the above-described configuration. In Figure 13, the solid curve 61 indicates the CRA corresponding to the image height h.

[0043] As shown in Figure 13, according to the optical device of the present embodiment, by configuring the lens 24 as described above, the increase in the CRA 61 accompanying the increase in the image height h is appropriately suppressed, so that the incident angle 61 does not become too large especially in the intermediate region (for example, 50% of the maximum image height Hmax) to a larger region of the image height h. Since this performance is obtained by controlling the diffused light from the aperture stop 17 with only one lens 24, it is also advantageous in terms of manufacturing cost.

[0044] Next, the optical device according to the third embodiment will be described. In the third embodiment, among the configurations of the optical device, the configuration of the illumination lens system is different from that of the first embodiment, and the configurations of the other parts (except for the design matters appropriately selected or adjusted by those skilled in the art) may be substantially the same as those of the first embodiment. Hereinafter, the description will be focused on the configuration of the lens.

[0045] Figure 14 shows a cross-sectional structure along the optical axis of the illumination lens system of the optical device according to the third embodiment. In Figure 14, the left straight line indicates the aperture 19 of the aperture stop 17, and the right straight line indicates the irradiation surface 7 (on this surface, the light receiving surface of the image sensor 8 is arranged during inspection). The diffused light enters from the left in the figure, passes through the aperture 19 and the lens 25 in sequence to become the inspection light 10 and reaches the irradiation surface 7.

[0046] The lens 25 is an aspherical lens of a non-imaging type having, for example, a disk shape or a polygonal plate shape centered on the optical axis 31. In the lens 25, in the figure, the dotted auxiliary line 25C indicates the outer edge of the effective lens region, and only the lens region inside that functions as a lens. The incident field, which is the region of the incident surface 25A of the lens 25 where the radius r ranges from zero to the incident field radius R1, and the exit field, which is the region of the exit surface 25B where the radius r ranges from zero to the exit field radius R2, contribute to the generation of the inspection light 10 that irradiates the light receiving surface of the image sensor 8.

[0047] FIG. 15 shows an example of the relationship between the radius r of the lens 25 and the refractive power (power) of the incident field of the incident surface 25A of the lens 25. As shown in FIG. 15, the power of the incident field of the incident surface 25A of the lens 25 has a negative value in the region where the radius r ranges from zero to the eighth radius R5 smaller than the incident field radius R1, and has a positive value in the region where the radius r ranges from the eighth radius R5 to the incident field radius R1. Further, this power increases continuously (i.e., without a step) as the radius r increases, and the rate of increase also increases or is partially constant.

[0048] FIG. 16 shows an example of the relationship between the radius r of the lens 25 and the refractive power (power) of the exit field of the exit surface 25B of the lens 25. As shown in FIG. 16, the power of the exit field of the lens 25 has a negative value in the region where the radius r ranges from zero to the ninth radius R6 smaller than the exit field radius R2, and has a positive value in the region where the radius r ranges from the ninth radius R6 to the exit field radius R2. Further, this power increases continuously (i.e., without a step) as the radius r increases. The rate of increase increases in the region where the radius r is relatively small as the radius r increases, and decreases in the region where the radius r is relatively large.

[0049] FIG. 17 shows an explanatory diagram of the relationship between the sag Z5 of the incident surface 25A of the lens 25 and the radius r. In the figure, the value of the sag Z5 is zero at the center point (optical axis position) through which the optical axis 31 of the incident surface 25A passes, positive on the incident side and negative on the exit side therefrom.

[0050] As shown in FIG. 17, the sag Z5 of the incident field of the incident surface 25A (the region where the radius r ranges from zero to the incident field radius R1) maintains a zero value or gently increases to the positive side as the radius r increases until it reaches the tenth radius R51 smaller than the incident field radius R1, and then further increases to the positive side as the radius r ranges from the tenth radius R5 to the incident field radius R1. That is, the incident field of the incident surface 25A has a shape that is more concave on the exit side near the center than in the peripheral portion.

[0051] Figure 18 shows an explanatory diagram illustrating the relationship between the sag Z6 and radius r of the exit surface 25B of the lens 25. In the figure, the value of sag Z6 is zero at the center point (optical axis position) through which the optical axis 31 of the exit surface 25B passes, and is positive on the incident side (left side in the figure) and negative on the exit side.

[0052] As shown in Figure 18, the sag Z6 of the exit field of view of the exit surface 25B (the region from radius r zero to exit field of view radius R2) decreases to the negative side as the radius r increases, from radius r zero to the 11th radius R61 which is smaller than the exit field of view radius R2, and then begins to increase from the 11th radius R61. The sag Z6 further increases as the radius r increases from the 11th radius R61, and at the 12th radius R62 which is larger than the 11th radius R61 but smaller than the exit field of view radius R2, it transitions from a negative value to a positive value and further increases up to the exit field of view radius R2. In other words, as the radius r increases, the exit field of view of the exit surface 25B has a shape in which the peripheral part bulges outwards from the center towards the exit side, and then concaves towards the incident side.

[0053] Figure 19 shows an example of the CRA characteristics on the illumination surface 7 by an optical device according to the third embodiment having the configuration described above. In Figure 19, the solid curve 71 shows the CRA corresponding to the image height h.

[0054] As shown in Figure 19, according to the optical device of this embodiment, by configuring the lens 25 as described above, the increase in CRA 71 with increasing image height h can be moderately suppressed, and the incident angle 71 can not become too large, especially in regions where the image height h is relatively large. In particular, in regions where the image height h is relatively large, the incident angle can be reduced as the image height h increases. This performance can be obtained by controlling the diffused light from the aperture diaphragm 17 with only one lens 25, which is also advantageous in terms of manufacturing costs.

[0055] Next, an optical device according to the fourth embodiment will be described. Figure 20 shows a cross-sectional view along the optical axis of the optical device 2 of the fourth embodiment. The same reference numerals are used for elements that are the same as those described in the first embodiment.

[0056] As shown in Figure 20, the optical device 2 does not have a lens between the aperture diaphragm 17 in the mirror 3 and the image sensor 8. The diffused light passing through the aperture 19 of the aperture diaphragm 17 directly becomes inspection light 10 and irradiates the image sensor 8 to be inspected. A cylindrical shielding wall 26 extending from the lens barrel 3 is provided in front of the exit direction of the aperture 19 of the aperture diaphragm 17. The shielding wall 26 prevents stray light from entering other image sensors 81 (especially other image sensors inspected simultaneously with the image sensor 8 to be inspected) by shielding the light emitted from the optical device 2 that is directed towards other image sensors 81.

[0057] Figure 21 is a cross-section taken along line A-A in Figure 20 (i.e., a cross-section perpendicular to the optical axis), showing an example of the cross-sectional shape of the shielding wall 26. As shown in Figure 21, the cross-sectional shape of the shielding wall 26 is circular, that is, the shielding wall 26 is cylindrical. Figure 22 shows another example of the cross-sectional shape of the shielding wall 26, in which case the cross-sectional shape of the shielding wall 26 is rectangular, that is, the shielding wall 26 is a rectangular cylinder. The aspect ratio of this rectangle may be, for example, the same as the aspect ratio of the image sensor 8, or a value selected according to the aspect ratio of the image sensor 8. Figure 23 shows yet another example of the cross-sectional shape of the shielding wall 26, in which case the cross-sectional shape of the shielding wall 26 is oblong or elliptical, that is, the shielding wall 26 is a rectangular cylinder. The aspect ratio of this oblong or elliptical may be, for example, the same as the aspect ratio of the image sensor 8, or a value selected according to the aspect ratio of the image sensor 8. The cross-sectional shape of the shielding wall 26 may be other than the shapes exemplified in Figures 21 to 23. Regardless of the shape of the shielding wall 26, the dimensions of the shielding wall 26 are chosen such that the entire light-receiving surface of the image sensor 8 to be inspected is contained within the area illuminated by the inspection light 10 emitted from the shielding wall 26 onto the inspection surface 7, but the light-receiving surfaces of other image sensors 81 are not contained within that area at all.

[0058] Next, an optical device according to the fifth embodiment will be described. Figure 24 shows a cross-sectional view along the optical axis of the optical device 4 according to the fifth embodiment. Elements identical to those described in the first embodiment are denoted by the same reference numerals.

[0059] As shown in Figure 24, the optical device 4 according to the fifth embodiment has a lens system 32 in front of the exit direction of the aperture diaphragm 17 inside the lens barrel 3, and a shielding wall 27 extending from the lens barrel 3 in front of the exit direction of the lens system 32. The lens system 32 only needs to be capable of generating inspection light 10 having the characteristics required for inspecting the image sensor 8, and may be, for example, a single lens similar to the lenses 23, 24, or 25 in the first to third embodiments illustrated in Figure 24, or it may be a set of multiple lenses. The shielding wall 27 serves the same purpose as the shielding wall 26 in the fourth embodiment, that is, it shields the light emitted from the lens 23 that is directed toward other image sensors (in particular, other image sensors inspected simultaneously with the image sensor to be inspected) 81 other than the image sensor 8 to be inspected.

[0060] Here, the cross-sectional shape of the shielding wall 27 may be circular, rectangular, oval, or elliptical, as illustrated in Figures 21 to 23, or another shape, similar to the shielding wall 26 in the fourth embodiment. The aspect ratio of the cross-sectional shape of the shielding wall 27 may be a value corresponding to the aspect ratio of the image sensor 8.

[0061] Next, an image sensor inspection apparatus having multiple optical devices according to the sixth embodiment will be described. Figure 25 shows a cross-sectional view along the optical axis of each optical device 4 in the inspection apparatus according to the sixth embodiment. The same reference numerals are used for elements that are the same as those described in the fifth embodiment.

[0062] As shown in Figure 25, in the image sensor inspection apparatus 100 according to this embodiment, the cross-sectional shape of the lens barrel 3 and shielding wall 27 in a direction perpendicular to the optical axis of each optical device 4 (or the cross-sectional shape with the largest size among the lens barrel 3 and shielding wall 27) is, for example, a rectangle as shown in Figure 22 (particularly, a rectangle with an aspect ratio corresponding to the aspect ratio of the image sensor). Multiple (or many) optical devices 4, 4 having the same configuration are arranged in one or two dimensions at the same pitch 101 as multiple (or many) image sensors 8, 81 on the wafer. Multiple optical devices 4 can simultaneously inspect multiple adjacent image sensors 8, 81 on the wafer. Incidentally, conventional optical devices have a circular cross-sectional shape of their lens barrel, and multiple such optical devices are arranged in one or two dimensions with a certain amount of clearance between them. Therefore, although it is possible to simultaneously inspect at least every other image sensor among the many image sensors laid out on the wafer, it is difficult to simultaneously inspect multiple adjacent image sensors. In contrast, according to the image sensor inspection apparatus 100 of this embodiment, as shown in Figure 25, multiple optical devices 4 are arranged with very small clearances (or no clearances at all, that is, adjacent optical devices 4 share the walls of their lens barrels 4) at the same pitch 101 as the image sensors 8, 81, thereby enabling simultaneous inspection of multiple adjacent image sensors 8, 81 on a wafer, and thereby increasing inspection efficiency.

[0063] Next, an image sensor inspection apparatus having multiple optical devices according to a seventh embodiment will be described. Figures 26A and 26B show variations of the plan view of the light-shielding wall, i.e., the front end portion of the optical devices. Elements identical to those described in the previously described embodiments are denoted by the same reference numerals.

[0064] In the image sensor inspection apparatus 100 shown in Figure 26A, the front end portions of multiple optical devices 4 (in this example, multiple shielding walls 27, each defining a rectangular opening corresponding to a rectangular image sensor) are arranged with very small (or zero) clearances between them in a plan view from the wafer side. Here, each optical device 4 is separated from the other optical devices 4. On the other hand, in the image sensor inspection apparatus 100 shown in Figure 26B, the front end portions of multiple optical devices 4 (for example, multiple shielding walls 27) are configured as a grid-type common light-shielding wall 28 that defines multiple rectangular openings arranged in two or one dimension in a plan view from the wafer side. Therefore, the image sensor inspection apparatus 100 is integrated with each other, at least in its front end portions, and is not separated from one another.

[0065] Next, an image sensor inspection apparatus having multiple optical devices according to the eighth embodiment will be described. Figure 27 shows a cross-sectional view along the optical axis of each optical device 4 in the inspection apparatus according to the eighth embodiment. Elements identical to those described in the previously described embodiments are denoted by the same reference numerals.

[0066] In the image sensor inspection apparatus 100 according to this embodiment, each optical device 4 does not have a portion of its barrel 3 that surrounds the pre-optical system 11. That is, the barrel 3, for example, has only a portion that indicates the lens system 32, the aperture diaphragm 17, and the light-shielding wall 27, and the portion that surrounds the pre-optical system 11 as shown in Figure 25 is omitted. Furthermore, the pre-optical system 11 of each optical device 4 is configured so as not to leak out any extraneous light (stray light) that would interfere with other adjacent optical devices 4.

[0067] Next, an image sensor inspection apparatus having multiple optical devices according to the ninth embodiment will be described. Figure 28 shows a cross-sectional view along the optical axis of each optical device 4 in the inspection apparatus according to the ninth embodiment. Elements identical to those described in previously described embodiments are denoted by the same reference numerals.

[0068] In the image sensor inspection apparatus 100 according to this embodiment, multiple optical devices 4 share a single pre-optical system 11. The shared pre-optical system 11 supplies diffused light of the required specifications to the aperture diaphragm 17 of each optical device 4. The multiple optical devices 4 have a common lens barrel 3A surrounding the common pre-optical system 11 (or the lens barrel 3A may be omitted).

[0069] Next, an image sensor inspection apparatus having multiple optical devices according to the tenth embodiment will be described. Figure 29 shows a cross-sectional view along the optical axis of each optical device 4 in the inspection apparatus according to the tenth embodiment. The same reference numerals are used for elements that are the same as those described in the previously described embodiments.

[0070] In the image sensor inspection apparatus 100 according to this embodiment, similar to the ninth embodiment described above, multiple optical devices 4 share a single pre-optical system 11. The common lens barrel 3A surrounding the common pre-optical system 11, which was provided in the ninth embodiment, is omitted. In addition, each optical device 4 has one or more optical filters 16 that perform one or more predetermined optical adjustments or corrections (for example, adjusting the amount of diffused light passing through the aperture 19 according to the distance from the optical axis) on the diffused light from the pre-optical system 11.

[0071] Next, an image sensor inspection apparatus having multiple optical devices according to the 11th embodiment will be described. Figure 30 shows a cross-sectional view along the optical axis of each optical device 4 in the inspection apparatus according to the 11th embodiment. The same reference numerals are used for elements that are the same as those described in the previously described embodiments.

[0072] In the image sensor inspection apparatus 100 according to this embodiment, instead of a device that converts light from a general point light source, such as a lamp, into a light beam with a desired two-dimensional spread through a lens system, a planar light source 18 is used as the light source device that irradiates the input light beam 5 onto the pre-optical system 11. This planar light source 18 generates a light beam with a desired planar spread, such as an organic EL panel, a liquid crystal panel, or a arrangement of numerous LEDs in two dimensions. By controlling the numerous fine light-emitting elements of the planar light source 18, the planar distribution of the light emission amount, color, or other optical characteristics of the planar light source 18 can be adjusted as desired. This makes it possible to more precisely control the planar distribution of the intensity, color, and other characteristics of the light beam incident on each optical device 4.

[0073] Next, an image sensor inspection apparatus having multiple optical devices according to the twelfth embodiment will be described. Figure 31 shows a cross-sectional view along the optical axis of each optical device 4 in the inspection apparatus according to the twelfth embodiment. The same reference numerals are used for elements that are the same as those described in the previously described embodiments.

[0074] In the image sensor inspection apparatus 100 according to this embodiment, multiple optical devices 4 share a single pre-optical system 11, similar to the ninth or tenth embodiment described above. Furthermore, the lens barrel surrounding the pre-optical system 11 is omitted. Additionally, a planar light source 18, as described above, is used as the light source for irradiating the pre-optical system 11 with the input light beam 5.

[0075] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, by combining one or more components or characteristic configurations of the above-described embodiments, an optical device or inspection device having a different configuration from those described above may be realized without departing from the spirit of the invention.

[0076] 1, 2, 4: Optical device 3: Lens barrel 5: Input light beam 7: Illumination surface 8: Image sensor 9: Illumination field of view 10: Inspection light 11: Pre-optical system 17: Aperture diaphragm 19: Aperture 23, 24, 25: Lenses 23A, 24A, 25A: Incident surface 23B, 24B, 25B: Exit surface 26, 27: Shielding wall 31: Optical axis 32: Lens system 100: Image sensor inspection device 101: Pitch R1: Incident field of view radius R2: Exit field of view radius R3: First radius R11: Second radius R21: Third radius R22: Fourth radius R4: Fifth radius R31: Sixth radius R41: Seventh radius R5: Eighth radius R6: Ninth radius R51: Tenth radius R61: 11th radius R62: 12th radius Z1: sag Z2: sag Z3: sag Z4: sag Z5: sag Z6: sag h: image height r: radius

Claims

1. An optical device for irradiating the light-receiving surface of an image sensor with inspection light, comprising: a single lens having an optical axis, an incident surface, and an exit surface; and an aperture disposed on the incident side of the lens and having an opening at the center through which the optical axis passes, wherein diffuse light passes through the opening and is incident on the lens, and the inspection light is emitted from the lens, wherein the incident field of view of the incident surface, which is the region that contributes to the generation of the inspection light, has positive power throughout, and the exit field of view of the exit surface, which is the region that contributes to the generation of the inspection light, has negative power in a circular first region close to the optical axis and positive power in an annular second region further from the optical axis than the first region.

2. With respect to the sag of the incident surface and the exit surface of the lens, if the incident side is defined as the positive side and the exit side as the negative side along the optical axis from the center point through which the optical axis passes to each surface, the radius of the incident field of view is called the incident field of view radius, and the radius of the exit field of view is called the exit field of view radius, then the sag of the incident surface decreases to the negative side as the radius increases, from zero to a first radius smaller than the incident field of view radius, and then increases within the negative range from the first radius to the incident field of view radius, and the sag of the exit surface decreases to the negative side as the radius increases, from zero to a second radius smaller than the exit field of view radius, then increases from the second radius to a third radius larger than the second radius but smaller than the exit field of view radius, and then transitions from a negative value to a positive value at the third radius and increases up to the exit field of view radius, as described in claim 1.

3. An optical device for irradiating the light-receiving surface of an image sensor with inspection light, comprising: a single lens having an optical axis, an incident surface, and an exit surface; and an aperture disposed on the incident side of the lens and having an opening at the center through which the optical axis passes, wherein diffuse light passes through the opening and is incident on the lens, and the inspection light is emitted from the lens, wherein the incident field of view of the incident surface, which is the region that contributes to the generation of the inspection light, has negative power in a circular first region close to the optical axis and positive power in an annular second region further from the optical axis than the first region, and the exit field of view of the exit surface, which is the region that contributes to the generation of the inspection light, has positive power throughout.

4. With respect to the sag of the incident surface and the exit surface of the lens, if the incident side is defined as the positive side and the exit side as the negative side along the optical axis from the center point through which the optical axis of each surface passes, the radius of the incident field of view is called the incident field of view radius, and the radius of the exit field of view is called the exit field of view radius, then the sag of the incident surface maintains a zero value or increases to the positive side as the radius increases from zero to a first radius smaller than the incident field of view radius, and further increases to the positive side from the first radius to the incident field of view radius, and the sag of the exit surface maintains a zero value or increases to the positive side as the radius increases from zero to a second radius smaller than the exit field of view radius, and further increases to the positive side from the second radius to the exit field of view radius, as described in claim 3.

5. An optical device for irradiating the light-receiving surface of an image sensor with inspection light, comprising: a single lens having an optical axis, an incident surface, and an exit surface; and an aperture disposed on the incident side of the lens and having an opening at the center through which the optical axis passes, wherein diffuse light passes through the opening and is incident on the lens, and the inspection light is emitted from the lens, wherein the incident field of view of the incident surface, which is the region that contributes to the generation of the inspection light, has negative power in a first circular region close to the optical axis and positive power in a second annular region further from the optical axis than the first region; and the exit field of view of the exit surface, which is the region that contributes to the generation of the inspection light, has negative power in a third circular region close to the optical axis and positive power in a fourth annular region further from the optical axis than the third region.

6. With respect to the sag of the incident surface and the exit surface of the lens, if the incident side is defined as the positive side and the exit side as the negative side along the optical axis from the center point through which the optical axis passes to each surface, the radius of the incident field of view is called the incident field of view radius, and the radius of the exit field of view is called the exit field of view radius, then the sag of the incident surface remains at zero or increases to the positive side as the radius increases, from zero to a first radius smaller than the incident field of view radius, and further increases to the positive side from the first radius to the incident field of view radius, and the sag of the exit surface decreases to the negative side as the radius increases, from zero to a second radius smaller than the exit field of view radius, then begins to increase from the second radius, increases to a third radius larger than the second radius but smaller than the exit field of view radius, and then transitions from a negative value to a positive value at the third radius and increases to the exit field of view radius, as described in claim 5.

7. An optical device comprising an aperture having an output port for irradiating the light-receiving surface of an image sensor with inspection light, wherein the inspection light from the output port of the aperture is irradiated onto the light-receiving surface of the image sensor, wherein the optical device comprises a shielding wall located in front of the output port of the aperture in the direction of emission, which shields light from the output port toward other image sensors other than the image sensor.

8. An optical device for irradiating the light-receiving surface of an image sensor with inspection light, comprising a lens system and an aperture disposed on the incident side of the lens system and having an opening through which the optical axis passes, wherein diffuse light passes through the opening and then enters the lens, and the inspection light is emitted from the lens, the optical device further comprising a shielding wall in front of the lens system in the direction of emission, which shields light from the lens system toward other image sensors other than the image sensor.

9. The optical apparatus according to claim 7 or claim 8, wherein the cross-sectional shape of the shielding wall perpendicular to the optical axis has an aspect ratio corresponding to the aspect ratio of the image sensor.

10. An inspection apparatus for inspecting a plurality of image sensors on a wafer, comprising a plurality of optical devices for irradiating the light-receiving surfaces of the plurality of image sensors with inspection light, wherein the plurality of optical devices are arranged in one or two dimensions at the same pitch as the plurality of image sensors.

11. The inspection apparatus according to claim 10, wherein the cross-sectional shape of each of the plurality of optical devices perpendicular to the optical axis has an aspect ratio corresponding to the aspect ratio of the image sensor.

12. The inspection apparatus according to claim 10 or claim 11, wherein the front end portion of each of the plurality of optical devices has a common light-shielding wall of a grid type in which rectangular openings are arranged when viewed in plan from the wafer side.

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