Lens-testing apparatus and lens-testing method having a plurality of combinations of object distances

One embodiment of the invention provides a lens-testing apparatus being used for testing a lens device. The lens-testing apparatus comprises a light module, at least one first and second image sensors, and at least one image sensor module. The light module generates a patterned light beam passing the lens device. The first and second image sensors receive first and second portions of the patterned light beam; the first image sensor is disposed between the second image sensor and the lens device. The image sensor module receives a substantially parallel third portion of the patterned light beam, and comprises a third image sensor and a collimator. The third portion of the patterned light beam is focused onto the third image sensor by the collimator; the distance between the first image sensor and the lens device is smaller than the distance between the second image sensor and the lens device.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The invention relates to a lens-testing apparatus and a lens-testing method for testing a lens device, and more particularly, to a lens-testing apparatus and a lens-testing method for generating a plurality of combinations of object distances to test a lens device.

(b) Description of the Related Art

A lens device is wildly applied in optical devices, such as digital camera. During the manufacturing process, the quality of the lens device varies with the manufacturing difference. As a result, before delivered out of the factory, the lens device should be tested to confirm that the lens device can conform to the specification of original design.

FIG. 1shows a schematic diagram illustrating a conventional light box for testing a lens device. Referring toFIG. 1, the light box10comprises a housing11and a loading platform12, a light source13, at least one image sensor14, a host computer15, a test chart16and a lens device17which are disposed in the housing11. For testing different properties of the lens device17, different test charts16may be used. For example, during the test, light from the light source13shed on the test chart16passes through the lens device17and then is shed on the image sensor14. The image sensor14captures an image and transmits it to the host computer15. The host computer15is used to analyze the image captured and then the property of an image sensor14such as resolution, opto-electronic conversion function (OECF), gray value, modulation transfer function (MTF), spatial frequency response, etc. may be obtained.

However, the conventional light box10only can examine the lens device17at an object distance at a time. If the lens device17is requested to be examined at different object distances, a transmission device18should be provided in the conventional light box10to change the distance between the image sensor14and the lens device17. In addition, when the conventional light box10is used to examine a lens device at a large viewing angle or at a long object distance, it has to have a huge volume. Furthermore, the place for containing it has also to be a big space, so that the place is limited and the space thereof is wasted.

BRIEF SUMMARY OF THE INVENTION

In light of the above-mentioned problems, one object of an embodiment of the invention is to provide a lens-testing apparatus and a lens-testing method which use a plurality of combinations of object distances to examine a lens device. One object of an embodiment of the invention is to provide a lens-testing apparatus having a relatively compact volume. One object of an embodiment of the invention is to provide a lens-testing method used in a lens-testing apparatus so that the lens-testing apparatus may have a relatively compact volume.

One embodiment of the invention provides an lens-testing apparatus being used for testing a lens device. The lens-testing apparatus comprises a light module, at least one first image sensor, at least one second image sensor and at least one image sensor module. The light module is for generating a patterned light beam passing the lens device. The first image sensor is for receiving a first portion of the patterned light beam; the second image sensor is for receiving a second portion of the patterned light beam; the first image sensor is disposed between the second image sensor and the lens device. The image sensor module is for receiving a substantially parallel third portion of the patterned light beam, and comprises a third image sensor and a collimator. The substantially parallel third portion of the patterned light beam is focused onto the third image sensor by the collimator; the distance between the first image sensor and the lens device is smaller than the distance between the second image sensor and the lens device.

In one embodiment, the lens-testing apparatus further comprises at least one reflector disposed between the second image sensor and the lens device. The second portion of the patterned light beam is reflected by the reflector before received by the second image sensor.

One embodiment of the invention provides an lens-testing method being for testing an lens device, the lens-testing method comprising: (a) controlling a light module to generate a patterned light beam passing through the lens device, wherein a first portion of the patterned light beam is shed on a first image sensor; a second portion of the patterned light beam is shed on a second image sensor; and a substantially parallel third portion of the patterned light beam is shed on a image sensor module, wherein the image sensor module is used for simulating an object distance at infinity between the image sensor module and the lens device; and (b) using the first image sensor, the second image sensors and the image sensor module to capture the images corresponding to the patterned light beam, and analyzing the images to obtain the properties of the lens device.

Other objects and advantages of the invention can be better understood from the technical characteristics disclosed by the invention. In order to clarify the above mentioned and other objects and advantages of the invention, examples accompanying with figures are provided and described in details in the following.

DETAILED DESCRIPTION OF THE INVENTION

The above and other technical content, characteristics, and functions of the invention will be described in details with reference to the drawings. For clarity, the wording related to direction, such as up, down, left, right, front, back, etc., used in examples is referred to the direction with respect to the drawings. Therefore, the wording related to direction is not used to limit the scope of the invention.

FIG. 2shows a schematic diagram illustrating a lens-testing apparatus having a plurality of combinations of object distances according to one embodiment of the invention. Referring toFIG. 2, the lens-testing apparatus100having a plurality of combinations of object distances includes a first image sensor121having a short object distance, a second image sensor122ahaving a medium object distance and a third image sensor module120having a long object distance, a light module130and a lens device160. The lens device160is disposed between the light module130and the first image sensor121, the second image sensor122aand the third image sensor module120respectively. The distance between the second image sensor122aand the lens device160is an object distance D2. The distance between the first image sensor121and the lens device160is an object distance D1. The object distance D2is longer than the object distance D1. The light module130generates a patterned light beam. After passing through the lens device160, a first portion I1, a second portion I2and a third portion I3of the patterned light beam are respectively shed on the first image sensor121, the second image sensor122aand the third image sensor module120.

FIG. 3shows a schematic diagram illustrating a image sensor module according to one embodiment of the invention. Referring toFIG. 3, the third image sensor module120comprises a housing125, a third image sensor123having a long object distance and a collimator124. The third image sensor123and the collimator124are disposed in the housing125defining an opening126. The collimator124is disposed between the third image sensor123and the opening126. A portion of the patterned light beam shed on the third image sensor module120passes through the opening126and then becomes the third portion I3of the patterned light beam which is substantially parallel. The substantially parallel third portion I3is then focused onto the third image sensor123by the collimator124. It is preferred that the third image sensor123is disposed on a focus plane of the collimator124. As a result, the collimator124can simulate an object distance at infinity between the third image sensor123(the third image sensor module120) and the lens device160. The first image sensor121, the second image sensor122aand the third image sensor123respectively receive the first portion I1, the second portion I2and the third portion I3of the patterned light beam to capture images. The images may be analyzed by a control system to obtain the properties of the lens device160.

In one embodiment, the lens-testing apparatus100may further comprises a reflector170and a second image sensor122b. The reflector170is disposed between the lens device160and the second image sensor122b. The light module130generates a fourth portion I4of the patterned light beam which is shed on the reflector170. The fourth portion I4of the patterned light beam reflected by the reflector170is then shed on the second image sensor122b. In this embodiment, the requested volume of the lens-testing apparatus100is effectively reduced due to the provision of the reflector170.

In one embodiment, the light module130comprises a light source131and a test chart132. The light source131generates a light beam. The light beam becomes a patterned light beam after passing through the test chart. In addition, in order to test different properties of the lens device160, different test charts132may be used (as aftermentioned).

FIG. 4shows a schematic diagram illustrating a lens-testing apparatus which utilizes at least a reflector according to one embodiment of the invention. The lens-testing apparatus100as inFIG. 4is similar to lens-testing apparatus100inFIG. 2, and therefore the same numerical reference designates the same member in these lens-testing apparatus and the descriptions of the same members will be omitted. Only the difference between these lens-testing apparatus will be described in the followings. As shown inFIG. 4, lens-testing apparatus100aincludes a first loading platform221, a first reflector171and a second reflector172. The first reflector171and the second reflector172are respectively disposed between the first loading platform221and the lens device160and are opposite each other. Second image sensors122cand122dhaving a medium object distance are disposed on the first loading platform221. When the lens device160is requested to be examined at a predetermined largest viewing angle and the distance between the first loading platform221and the lens device160is distance D3, according to prior art, the first loading platform221should have a width W1such that the second image sensors122cand122dcan receive the light at the predetermined largest viewing angle. In this embodiment, the light module130generates a fifth portion I5of the patterned light beam being shed on the first reflector171, the fifth portion I5of the patterned light beam reflected by the first reflector171is shed on the second image sensors122cdisposed adjacent to the second end229of the first loading platform221. The light module130generates a sixth portion I6of the patterned light beam being shed on the second reflector172, the sixth portion I6of the patterned light beam reflected by the second reflector172is shed on the second image sensors122ddisposed adjacent to the first end228of the first loading platform221. The first end228is opposite the second end229. As a result, even though the first loading platform221has a width W2smaller than W1, the second image sensors122cand122dmay also receive the light from the lens device160at the predetermined largest viewing angle. This arrangement may reduce the volume of the lens-testing apparatus100a.

FIG. 5shows a schematic side view illustrating the inside of a lens-testing apparatus according to one embodiment of the invention. The lens-testing apparatus100binFIG. 5is similar to lens-testing apparatus100inFIG. 2, and therefore the same numerical reference designates the same member in these lens-testing apparatus and the descriptions of the same members will be omitted. Only the difference between these lens-testing apparatus will be described in the followings. In this embodiment, referring to theFIG. 5, the lens-testing apparatus100bincludes a housing111and a first displacement-generating device, at least one first image sensor121having a short object distance, at least one second image sensor122having a medium object distance and at least one third image sensor module120having a long object distance, at least one reflector170, a first loading platform221, a second loading platform222, a lens device160and a light module130which are disposed in the housing11. The first displacement-generating device is for moving the reflector170, the first image sensor121and the second image sensor122relative to the lens device160. In this embodiment, the displacement-generating device includes a first screw rod112and a second screw rod113. The first screw rod112and the second screw rod113are secured on the housing111. The second image sensor122is disposed on the first loading platform221. The first loading platform221is movably disposed on the second screw rod113so that which the second screw rod113may be used to move the second image sensor122. The first image sensor121is disposed on the second loading platform222being movably disposed at the first screw rod112, so that the first screw rod112may be used to move the first image sensor121. The second loading platform222is disposed between the lens device160and the first loading platform221, and the distance between the second image sensor122and the lens device160is longer than the distance between the first image sensor121and the lens device160.

FIG. 6shows a schematic top view of a loading platform of a lens-testing apparatus according to one embodiment of the invention. The second loading platform222includes at least one slide groove155and at least one carrier156. The second loading platform222defines the slide grooves155which pass through the second loading platform222. The reflectors170, the first image sensor121and the third image sensor module120are secured on the carriers156. At least one carriers156are movably disposed within the slide grooves155so that the carriers156may be moved within the slide grooves155forward or backward relative to the center of the second loading platform222. Consequently, the lens device160may be examined at different viewing angles. A hole157is formed at the center of the second loading platform222, so that the light from the lens device160may pass through the hole157and then be shed on the second image sensor122. The slide grooves155(the carriers156) are arranged in pairs and each pair of the slide grooves155(the carriers156) are respectively disposed at the opposite sides of the hole157. This arrangement can make sure that the first image sensor121and the third image sensor module120capture a symmetrical combination of images.

FIG. 7shows a schematic top view of a loading platform of a lens-testing apparatus according to one embodiment of the invention. The first loading platform221includes at least one slide rail161. At least one second image sensor122are movably disposed at the slide rail161so that the second image sensor122may be moved along the slide rail161forward or backward relative to the center of the first loading platform221. Consequently, the lens device160may be examined at different viewing angles. In one embodiment, a second image sensor122famong the second image sensors122is disposed at the center of the first loading platform221, and the others among the second image sensors122are arranged in pairs; each pair of the second image sensors122are respectively disposed at the opposite sides of the second image sensor122f. This arrangement can make sure that the second image sensors122capture a symmetrical combination of images.

Referring toFIG. 5, the lens-testing apparatus100bmay further includes a fourth image sensor127having a tiny object distance, a third loading platform223and a second displacement-generating device114. The fourth image sensor127is disposed on the side surface of the third loading platform223adjacent to the lens device160, and the third loading platform223is connected to the second displacement-generating device114. The second displacement-generating device114is disposed on the side surface of the second loading platform222adjacent to the lens device160, and it may optionally move the third loading platform223so that the fourth image sensor127may be moved to the space between the second loading platform222and the lens device160. The structure of the second displacement-generating device114is not limited in the present invention; in one embodiment, the second displacement-generating device114may include a motor and a connecting rod (not shown). The third loading platform223is secured at the connecting rod. The motor and the connecting rod are connected through a saw teeth structure so that the motor may drive the connecting rod to move forward and backward. In another embodiment, the motor may rotate the connecting rod and drives the third loading platform223and the fourth image sensor127to rotate so that the fourth image sensor127may be optionally located between the second loading platform222and the lens device160.

FIG. 8shows a schematic diagram illustrating a control system of a lens-testing apparatus according to one embodiment of the invention, in which the control system is shown by a function block. The lens-testing apparatus100chaving a plurality of combinations of object distances inFIG. 8is similar to lens-testing apparatus100binFIG. 5, and therefore the same numerical reference designates the same member in these lens-testing apparatus and the descriptions of the same members will be omitted. Only the difference between these lens-testing apparatus will be described in the followings. For simplicity, the members such as screw rod are omitted inFIG. 8. In this embodiment, lens-testing apparatus100cmay further includes a control system300. The control system300includes an image controller301and a host computer302. The image controller301is coupled to the first image sensor121, the second image sensor122, the third image sensor module120(third image sensor123) and the fourth image sensor127. The host computer302may be a computer having calculating functions and is coupled to the image controller301and the second displacement-generating device114. The host computer302controls the second displacement-generating device114to move the third loading platform223. The host computer302may also receive the images captured by the image sensors through the image controller301and then analyze the images to obtain the properties of the lens device160. The lens-testing apparatus100cis also controlled by the control system300so as to perform a lens-testing method for testing a lens device160.

FIG. 9shows a flow chart illustrating a lens-testing method for testing a lens device according to one embodiment of the invention. The lens-testing method may test the lens device160at different viewing angles. The method comprises the following steps.

Step02: controlling a light module130to generate a patterned light beam passing through the lens device160; wherein a first portion I1of the patterned light beam is shed on the first image sensor121; a second portion I2of the patterned light beam is shed on the second image sensor122; and the third portion I3of the patterned light beam is shed on the third image sensor module120. In one embodiment, the second portion I2is reflected by the reflector170before shed on the second image sensor122. The third image sensor module120can simulate an object distance at infinity between the third image sensor module120and the lens device160.

Step04: using the first image sensor121, the second image sensors122and the third image sensor module120to capture the images corresponding to the patterned light beam, and analyzing the images to obtain the properties of the lens device160.

FIGS. 10A to 10Brespectively show a test chart according to one embodiment of the invention. As shown inFIG. 10A, the test chart132aincludes a plurality of squares421. The borders423and424of the squares421respectively extend along the vertical direction and the horizontal direction. In order to obtain a relatively good test result, the squares421are opaque (black) and are disposed on a transparent (white) surface. As shown inFIG. 10B, the test chart132bincludes a plurality of cross areas431. The borders432and433of the cross areas431respectively extend along the vertical direction and the horizontal direction. In order to obtain a relatively good test result, the cross areas431are opaque and are disposed on a transparent surface.

FIGS. 11A to 11Brespectively show a schematic diagram illustrating an image sensor according to one embodiment of the invention. As shown inFIG. 11A, the shape of the image sensor may be a surface shape165such that the images of the area651inFIGS. 10Ato10B may be captured. As shown inFIG. 11B, the shape of the image sensor may comprise a first stripe166extending along the vertical direction and a second stripe167extending along the horizontal direction such that the images of the area661and671inFIGS. 10A to 10Bmay be captured.

The lens-testing test method according to this embodiment may test the properties of the lens device160. The test method of using different test charts132in the light module130to calculate the characteristics of spatial frequency responses of the images captured by the image sensors is described in the following as an example. In one embodiment, as shown inFIG. 10A, the steps of analyzing the images corresponding to the test chart132amay comprise the following steps (not shown). Step42: calculating edge spread functions of the borders in the vertical direction and the horizontal direction. Step43: calculating a line spread function by differentiating the edge spread functions. Step44: calculating a spatial frequency response by conducting a fourier transform on the line spread function. In one embodiment, as shown inFIG. 10B, the steps of analyzing the images corresponding to the test chart132bmay comprise the following steps (not shown). Step52: calculating a line spread function in the vertical direction and the horizontal direction. Step54: calculating a spatial frequency response by conducting a fourier transform on the line spread function.

An object of an embodiment of the invention is to improve the convenience of a lens-testing apparatus or a lens-testing method, and to provide a lens-testing apparatus or a lens-testing method which is more efficient than the conventional one. In one embodiment, a reflector is disposed adjacent to a first image sensor having a short object distance. A second image sensor having a medium object distance is disposed at the place on which the light beam reflected by the reflector can be shed so that the light path is extended. A third image sensor module having a long object distance is disposed adjacent to the reflector. The third image sensor module includes a collimator capable of collimating the light and simulating an object distance at infinity. Consequently, the lens-testing apparatus and method may have third different object distances. In one embodiment, the image sensors (or image sensor module) and reflector may be disposed at a first displacement-generating device which can adjust the highs thereof so that the object distances are varied. In one embodiment, a control system is provided to satisfy different test requests in various modes.

Although the preferred embodiments of the present invention has been fully described by way of examples with reference to the accompanying drawings, it should not be construed as any limitation on the implementation range of the invention. Various equivalent changes and modifications can be performed by those who are skilled in the art without deviating from the scope of the invention. The scope of the present invention is to be encompassed by the claims of the present invention. Any embodiment or claim of the present invention does not need to reach all the disclosed objects, advantages, and uniqueness of the invention. Besides, the abstract and the title are only used for assisting the search of the patent documentation and should not be construed as any limitation on the implementation range of the invention.