Patent Application
20080149853
The present invention relates generally to light shaping apparatuses for illuminating imaging devices and, in particular, embodiments of the present disclosure relate to light shaping apparatuses for illuminating imaging devices during testing.
During the manufacture of imaging devices (e.g., solid-state imagers), such as a Complementary Metal Oxide Semiconductor (CMOS) or a Charge Coupled Device (CCD), the testing of the photoelectric conversion portion of the device is often accomplished. In such manufacturing processes, the imaging device is often formed on a semiconductor wafer. Accordingly, the testing of the photoelectric conversion portion and the other components of the device can be tested at the same time, or in a sequence.
The testing of one or more other components is, for example, performed by a probe card. If the testing apparatus (e.g., probe card) has testing components to complete the photoelectric conversion portion and the other components, the testing apparatus may be maintained in the same position and, thereby, testing can be accomplished more quickly, among other benefits.
In such tests, a test light from a light source can be directed to a light receiving surface (e.g., an active area) of the imaging device through an aperture in the testing apparatus. However, the light used for testing is typically not similar to the light that will actually be received by the imaging device in the field. Accordingly, although the device may pass the test measures, it may be that the device is not suitable for some applications.
For example, such testing apparatuses utilize one or more lenses to direct the light toward the light receiving surface. These lenses can create too much intensity over a portion of or the entire light receiving surface. Further, since the probe card and/or a socket board are typically positioned between the light source and the imaging device, the degree of freedom of orientation is restricted.
Additionally, in some testing processes, a collimated light is used to perform the test. In some instances (e.g., as pixel size has decreased, while the chief ray angle of the testing apparatus remained substantially the same) the intensity of the light projected on the imaging device tended to increase to the point where the imaging device became difficult to test.
The present disclosure includes various apparatuses and methods for shaping light. Embodiments of the present disclosure can be used to direct light at an imaging device under test, for example, during a manufacturing or post-manufacturing process.
Embodiments of the present disclosure can utilize a diffuser located adjacent to an aperture through which the light is directed at the imaging device. Embodiments can also be arranged such that light from a light source can directly enter the diffuser from the light source.
This can be advantageous in some applications, for example, where a lens would get dirty or dusty. Also, light that has not been through a lens may, in some instances be more like the light that will be directed toward the imaging device in the field and therefore, the test may be more indicative of field conditions. Embodiments that do not use a lens, typically also have less components and therefore may have less maintenance issues and be less expensive.
In some embodiments, the light may be collimated before it is directed into the diffuser. In such embodiments, the collimated light can be directed to the imaging device in a more predictable manner, which may be desirable for some types of testing.
In some embodiments, a light shaping apparatus can include a diffuser to diffuse an intensity of a light passed through the diffuser. Such embodiments can also include an aperture forming layer having a first surface and a second surface and having an aperture formed therebetween. In such embodiments, the apparatus can be designed such that the first surface is adjacent to a surface of the diffuser.
The aperture can be oriented to direct the light from the diffuser toward a light receiving surface of an imaging device. If a collimated light source is desired, the light can be collimated at the light source or after the light leaves the light source.
The apparatus can include a test fixture having a number of sets of diffusers and apertures that receive light from a single light source or multiple sources. For example, the apparatus can include a test fixture having a number of sets of diffusers and apertures that receive each receive light from different light sources.
The diffuser can be of various shapes. For example, the diffuser can be a cylindrical shaped diffuser. Such embodiments, can, in some instances, present a more uniform light intensity distribution to the imaging device, among other benefits.
The diffuser can be arranged in various positions with respect to the other components of the apparatus. For example, in some embodiments, the end surface of the diffuser is adjacent to the aperture. The diffuser can, for instance, be positioned such that the light enters the diffuser directly from a light source.
The diffuser can be made from a variety of suitable materials. For example, in some embodiments, the diffuser can be made from glass. A glass such as an opal glass material is one example of a suitable glass type material. In some embodiments, a Lambertian profile may be desirable and an opal glass material can be used in such embodiments.
The present disclosure also includes a number of testing apparatus embodiments. In such embodiments, the testing apparatus can include a number of testing components. For instance, a testing device can include a probe portion having a number of contact probes thereon for contacting pads on an imaging device.
In some embodiments, the testing device can have an imaging test portion. In such embodiments, the imaging test portion can, for example, have a light source, a diffuser to diffuse an intensity of a light generated by the light source and directly passed through the diffuser, and an aperture forming layer having a first surface and a second surface and an aperture formed therebetween.
When a probe portion and an imaging test portion are provided together, the probe portion and the imaging test portion can, for example, be positioned such that at least one contact probe can be in contact with a pad while light is being directed from the diffuser toward the light receiving surface of the imaging device. Such embodiments can allow for simultaneous, parallel, or serial testing by the probe portion and the imaging test portion, which, in some instances can save time during the manufacturing or post-manufacturing process, among other benefits.
In some light shaping apparatus embodiments, the light shaping apparatus can include a diffuser to diffuse an intensity of a light passed through the diffuser and an aperture forming layer having a first surface and a second surface and having an aperture formed therebetween. In some such embodiments, the first surface is adjacent to a surface of the diffuser.
In various embodiments, the aperture can be oriented to direct the light from the diffuser toward a light receiving surface of an imaging device, where a chief ray angle of the imaging device is between an upper angle of incidence and a lower angle of incidence of light contacting the light receiving surface. In such embodiments, having the chief ray angle within the upper and lower angles of incidence can be beneficial because the light directed toward the imaging device covers the surface of the active area of the device with light that is properly oriented to each pixel location on a die.
The chief ray angle of the imaging device that is to be tested can be used with respect to the positioning of the various components of the apparatus. For example, the diameter of the aperture can be sized based upon an analysis of the chief ray angle of the imaging device and a comparison of the chief ray angle to the lower angle of incidence and the upper angle of incidence of the aperture.
In some embodiments, The aperture can have a diameter that is sized based upon the chief ray angle of the imaging device and a distance of the aperture from the imaging device. Additionally, the aperture can have a distance from the imaging device that is based upon the chief ray angle of the imaging device and a diameter of the aperture, in some embodiments.
The present disclosure also includes a number of method embodiments. For example, in some method embodiments, the method can include generating a light from a light source passing the light directly through a diffuser, and passing the light from the diffuser through an aperture, wherein the aperture is oriented to direct the light from the diffuser toward a light receiving surface of an imaging device.
Method embodiments can include determining an aperture diameter that defines a light cone that envelops a chief ray angle of the imaging device across a diagonal of the light receiving surface. A testing apparatus chief ray angle can be based upon taking an arc tangent of an image height of the imaging device divided by a distance of the aperture from the imaging device and such calculating processes can be perform in some embodiments.
Methods of determining the aperture size and position can be provided. For example, methods can include determining an aperture diameter based upon a chief ray angle of the imaging device and a distance of the aperture from the imaging device. In some embodiments, a method can include determining a distance for positioning the aperture from the imaging device based upon a chief ray angle of the imaging device and a diameter of the aperture.
One or more alignment fixtures, such as fixture 110, can be used to make adjustments to the alignment of the diffusers and/or apertures in order for them to be aligned with respect to the light source. This can be beneficial, in some embodiments, because the test card 122 does not have to be moved, and/or, in some embodiments, the diffusers and apertures can be aligned without taking the apparatus apart, among other benefits.
Also, as illustrated in the embodiment of
When the apparatus is assembled, it functions to receive light from a light source (not shown) through the holes in the retainer plate 112. That light is passed through the diffuser 116 and apertures, as will be discussed in more detail below, formed in the diffuser mounting structure 118. The apparatus 100 directs light toward an imaging device, described in more detail in
The imaging device also can include a number of contacts thereon. The contacts are used to create paths to and from the imaging device and other devices of a larger system. For example, some contacts can be used to provide power, from a power source, to the imaging device in order to power its circuitry.
Also illustrated is an integrated circuit 232 that is used to execute instructions. The integrated circuit 232 can be operably coupled to the active area 228 to execute instructions regarding the use of the pixels within the active area 228. The imaging sensor 211 can be of various types. For example, imaging devices can be solid state-type devices such as complementary metal-oxide-semiconductor (CMOS) devices, charged coupled device (CCD) image sensors, or other imaging device types for capturing images in the visible (e.g., visible to the human eye) or non-visible spectrum (e.g., Infrared or Ultra-violet).
In such embodiments, the light source 333 can be any suitable type. For example, a light emitting diode (LED) is one suitable type of light source for providing light to the device under test (DUT) 311. Another example is a halogen light, such as a collimated halogen light source.
Additionally, as stated above, some testing systems can utilize multiple light sources. For instance, a different light source can be associated with each aperture, in some embodiments.
With respect to the aperture forming layer, the layer can have a thickness or can be as thin as practical. The aperture layer has a first surface (e.g., a top surface), a second surface (e.g., a bottom surface), and the aperture is formed through both the first and second layers and spans therebetween. In some embodiments, the aperture measurements can be made from the top surface and/or from the bottom surface.
Also illustrated in the embodiment of
These dimensional elements can be used in designing the system, or testing apparatus or in adjusting the positions of the various components, for example, based upon use of the testing apparatus with different types of imaging devices. For example, the aperture size (e.g., based upon diameter, circumference, etc.) can be designed such that the resulting directed light (e.g., a light cone) projects over the entire surface of the imaging device, in some embodiments.
The aperture distance from the device under test can also be used to create the suitable projection over the device under test. Some calculations based upon these elements are discussed elsewhere in this disclosure.
In various embodiments, the aperture diameter can be adjustable or fixed. In some embodiments, an aperture forming layer can be replaced with another layer having a different sized aperture or a layer of a different thickness. The aperture forming layer can also include an iris for changing the aperture diameter, in some embodiments.
Further, in various embodiments, an aperture forming layer can be positioned adjacent to the diffuser or spaced therefrom. In some embodiments, the spacing can be adjusted by a suitable movable mechanism for moving the layer, or changed by removing one layer and replacing it with one or more other layers to provide a different spacing. The other dimensional elements discussed above can also be fixed or adjustable, in similar manners, in various embodiments.
The testing device 400 that is illustrated in
In
One or more diffusers 416 can be placed within the number of cavities to diffuse light directed from one or more light sources (not shown). In such embodiments, one or more diffuser retainers (e.g., such as that shown in the embodiment of
If a transparent diffuser retainer is used, it may aid in keeping the diffuser free from dirt, debris, and other contaminants. In such embodiments, it may be easier and more cost effective to replace the diffuser retainer rather the diffuser itself. Further, in some embodiments, the diffuser retainer may be made from a material that is more receptive to cleaning and therefore it can protect the diffuser from potential damage due to cleaning.
The light sources are identified as being a distance L from the aperture. In some embodiments, the distance L will be a vertical distance to the light source even though the light source may not be directly above the aperture to which the measurement is associated.
The embodiment of
As with the embodiment illustrated in
The collimating structure 538 collimates the light 542 that is directed into the cavities containing the diffusers 516. In some apparatus or system embodiments, the testing apparatus can have one or more diffusers and one or more light sources. The collimated light can be passed through the diffusers 516 and apertures and toward associated imaging devices (not shown).
For example, the light cone presented to the imaging device (e.g., light cone 436 of the apparatus embodiment of
Some imaging devices have lenses (e.g., a microlens) formed or attached above the active area of the device. In such instances, the imager CRA can be calculated as the chief ray angle of the light focused onto the active area of the device (e.g., light sensor array) by the microlens of the device, given the distance from the optical center of the active area, defined by the image height, for example, as can be accomplished with the method described in
The information in the graph of
As shown in
For example, the angles can be calculated by finding the angle of incidence from both edges of the aperture to points along the image height. In such embodiments, the centering of the apparatus can be determined by whether the center of the aperture associated with the device under test is centered over the optical center of the active area. In some embodiments, these calculations can be based upon a theoretical device, such as if the calculation is being done before the apparatus is constructed or before a device is associated with the testing apparatus.
For example, in the graph of
The present disclosure includes various apparatuses and methods for shaping light. Embodiments of the present disclosure can be used to direct light at an imaging device under test, for example, during a manufacturing or post-manufacturing process.
Embodiments of the present disclosure can be advantageous in some applications, for example, where a lens would get dirty or dusty. Also, light that has not been through a lens may, in some instances, be more like the light that will be directed toward the imaging device in the field and therefore, the test may be more indicative of field conditions.
Embodiments that do not use a lens, typically also have less components and therefore may have less maintenance issues and be less expensive. Embodiments, can, in some instances, present a more uniform light intensity distribution to the imaging device, among other benefits.
Embodiments having probing capabilities can allow for simultaneous, parallel, or serial testing by the probe portion and the imaging test portion, which, in some instances, can save time during the manufacturing or post-manufacturing process, among other benefits. The present disclosure also includes embodiments, having the chief ray angle of the imaging device within the upper and lower angles of incidence of the aperture, which can be beneficial because the light directed toward the imaging device covers the surface of the active area of the device.
The dimensional elements of an imaging device or system can be calculated to provide the desired coverage of light upon a device under test. This can be accomplished, for example, prior to building the testing apparatus or system or when the device or system is adjusted.
Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art will appreciate that an arrangement calculated to achieve the same results can be substituted for the specific embodiments shown. This disclosure is intended to cover adaptations or variations of various embodiments of the present disclosure.
It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combination of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description.
The scope of the various embodiments of the present disclosure includes other applications in which the above structures and methods are used. Therefore, the scope of various embodiments of the present disclosure should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.
In the foregoing Detailed Description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the disclosed embodiments of the present disclosure have to use more features than are expressly recited in each claim.
Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.
