HK1183712A - Ir-cut filter having red absorbing layer for digital camera - Google Patents

Abstract

An infrared cut filter may be used with an image sensor to remove infrared light components from image light received from a first side of the infrared cut filter prior to the image light reaching the image sensor to be disposed on a second side of the infrared cut filter. The infrared cut filter includes at least one red absorbing layer and an infrared reflector. The at least one red absorbing layer partially absorbs red light components within the image light. The infrared reflector reflects the infrared light components. The infrared reflector is disposed between the red absorbing layer and the first side of the infrared cut filter while the at least one red absorbing layer is disposed between the infrared reflector and the second side of the infrared cut filter.

Description

Infrared cut-off filter with red absorption layer for digital camera

Technical Field

The present disclosure relates generally to digital cameras, and particularly, but not exclusively, to infrared ("IR") cut-off filters for use in digital cameras.

Background

Digital cameras are ubiquitous. They are used in a wide variety of devices, from expensive and complex equipment to cellular telephones and webcams. The digital still camera or video camera includes at least one imaging lens and an image sensor. Typically, the image sensor is a complementary metal oxide semiconductor ("CMOS") image sensor, but charge coupled device ("CCD") image sensors are also possible. The imaging lens forms an image at the image sensor. The image sensor typically includes millions of pixels or light sensing elements that are sensitive to one of the three primary colors, e.g., red, green, and blue. Each pixel detects and converts the light intensity at the pixel into an electrical signal. Accordingly, a color image formed by the imaging lens is detected and converted into an electric signal. In other words, the optical color image is converted into an electronic color image by the image sensor.

CMOS and CCD image sensors are also typically sensitive to near infrared light, as compared to the human eye. Near infrared light or IR light as referred to in the present invention for simplicity will also be detected. However, CMOS and CCD image sensors are typically not sensitive to IR light beyond the near infrared spectrum. The detected IR image produces errors in the displayed image produced in three primary colors, e.g., red, green, and blue.

To eliminate or reduce errors caused by the detected IR image in the generated primary color image, an IR cut filter ("IRCF"), also referred to as an IR cut filter, is disposed between the imaging lens and the image sensor such that IR light is blocked by the IR cut filter while visible light is transmitted through the IR cut filter. Thus, the use of an IR cut filter enables more realistic colors with white light. However, the IR cut filter may cause other problems as described in the following section.

Disclosure of Invention

One aspect of the present invention relates to a camera apparatus. The camera apparatus includes: an image sensor to capture image light and generate an image in response to the image light; an imaging lens optically aligned with the image sensor to focus the image light onto the image sensor; and an infrared cut filter disposed between the imaging lens and the image sensor to remove an infrared light component from the image light before the image light reaches the image sensor. The infrared cut filter includes: at least one red absorbing layer that partially absorbs a red light component within the image light; and an infrared reflector that reflects the infrared light component, the infrared reflector disposed between the red absorbing layer and the imaging lens.

Another aspect of the invention relates to an infrared cut-off filter for use with an image sensor to remove an infrared light component from image light received from a first side of the infrared cut-off filter before the image light reaches the image sensor to be disposed on a second side of the infrared cut-off filter. The infrared cut filter includes: at least one red absorbing layer that partially absorbs a red light component within the image light; and an infrared reflector that reflects the infrared light component. The infrared reflector is disposed between the red absorbing layer and the first side of the infrared cut filter. The at least one red absorbing layer is disposed between the infrared reflector and the second side of the infrared cut filter, the second side being opposite the first side.

Drawings

Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described. In the drawings, the thickness of layers and regions may be exaggerated for clarity.

FIG. 1 shows a digital camera including an imaging lens, an image sensor, and an IR cut filter for removing IR images.

FIG. 2 shows an IR cut filter including an IR reflective film that reflects IR light.

FIG. 3 shows an IR reflecting film that also reflects some red light and produces a ghost image.

FIG. 4 shows an IR cut filter including an IR reflective film, a transparent substrate, and a red absorbing film according to an embodiment of the invention.

FIG. 5 shows an IR cut filter including an IR reflective film and a red absorbing substrate according to an embodiment of the invention.

FIG. 6 shows an IR cut filter including an IR reflective film, a red absorbing substrate, and a red absorbing film, according to an embodiment of the invention.

FIG. 7 shows the embodiment of FIG. 5 further including an antireflective ("AR") film according to an embodiment of the invention.

Figure 8 shows the figure 4 embodiment further including an AR film according to an embodiment of the invention.

Figure 9 shows the figure 6 embodiment further including an AR film according to an embodiment of the invention.

Fig. 10a and 10b illustrate exemplary magnitudes of red light reflected by an IR cut filter (a) with a red absorbing layer and (b) without a red absorbing layer, according to embodiments of the invention.

FIG. 11 is a functional block diagram illustrating an imaging system according to an embodiment of the present invention.

Detailed Description

An embodiment of an IR cut filter used in a digital camera is described. Numerous specific details are described to provide a thorough understanding of embodiments of the invention, but one skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects, but are still within the scope of the invention.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one described embodiment. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in this specification do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Fig. 1 shows a digital camera 100 that includes an imaging lens 102, an image sensor 104 (e.g., a CMOS or CCD image sensor), and an IR cut filter 106 disposed between the imaging lens 102 and the image sensor 104. The imaging lens 102 forms an image of an object 108 at the image sensor 104. Light 110 from the object 108 passes through the imaging lens 102 and the IR cut filter 106 and reaches the image sensor 104. The IR component of the light 110 is blocked by the IR cut filter 106, so the image formed at the image sensor 104 contains little or no IR light components.

Fig. 2 shows an IR cut-off filter 106 used in a digital camera, such as the digital camera 100 illustrated in fig. 1. The IR cut filter 106 includes a transparent substrate 202. The transparent substrate 202 is typically made of glass, although other materials may be used. An IR reflecting film 204 is disposed on the substrate 202 facing the imaging lens 102. The IR reflecting film 204 may be an interference filter formed from a single or multiple layer coating. Light 110 from an object 108 passes through the lens 102 and is incident on the IR cut filter 106. Due to light interference, the IR light component 212, which is a portion of the incident light 110, is reflected by the IR reflecting film 204. The remaining components of the incident light 110, including the visible light components (e.g., the three primary colors, such as red, green, and blue), are transmitted through the IR reflecting film 204 into transmitted light 214. An anti-reflection ("AR") film 206 is disposed on the opposite side of the substrate 202 facing the image sensor 104. The AR film 206 may be fabricated as a single layer or a multi-layer coating.

The transmitted light 214 forms a primary image 230 that is incident on the image sensor 104. The pre-image 230 contains no or significantly reduced IR light components. A substantial portion of the transmitted light 214 is absorbed by the image sensor 104 and produces an electronic image. A small portion of the transmitted light 214 is reflected at the surface of the image sensor 104 to become reflected light 216. The reflected light 216 may result from reflection at the surface, diffraction caused by pixel structures within the image sensor 104, or both. The reflected light 216 propagates through the AR film 206, the transparent substrate 202, and the IR reflecting film 204 (in the case where the IR reflecting film 204 reflects only IR light and transmits visible light including red light).

In general, the IR cut filter 106 is disposed between the imaging lens 102 and the image sensor 104. The IR cut filter 106 includes a transparent substrate 202, an IR reflective film 204, and an AR film 206. An IR reflective film 204 is disposed on the transparent substrate 202 facing the imaging lens 102, and an AR film 206 is disposed on the other side of the substrate 202 facing the image sensor 104.

Fig. 3 illustrates how the IR reflecting film 304 of the IR cut filter 300 does not completely transmit all visible light components of the incident light 110. Rather, some visible light, especially red light near the IR spectrum (e.g., λ > 630nm), may be partially reflected by the IR reflective film 304 along with the IR light, becoming reflected light 312. In other words, the reflection spectrum of the IR reflecting film 304 contains red light. The remainder of the incident light 110, which may contain less red light components and little or no IR light components, is transmitted through the IR reflecting film 304 to become transmitted light 314. The transmitted light 314 is transmitted through the transparent substrate 202 and the AR film 206 to form the pre-image 230 on the image sensor 104. A substantial portion of the transmitted light 314 is absorbed by the image sensor 104 to produce an electronic image. However, a small portion of the transmitted light 314 is reflected at the surface of the image sensor 104 to become reflected light 316. The reflected light 316 may result from reflection at the surface, diffraction caused by pixel structures within the image sensor 104, or both. The reflected light 316 is transmitted through the AR film 206 and the substrate 202. Since the reflection spectrum of the IR reflection film 304 contains red light, the red light contained in the reflected light 316 is partially reflected by the IR reflection film 304 to become red reflected light 320. The remainder of the reflected light 316 passes through the IR reflecting film 304 to become transmitted light 318.

The red reflected light travels back through the substrate 202 and the AR film 206 and again reaches the image sensor 104 to form a red secondary image 332, referred to as a ghost image. Thus, the red reflected light 320 is detected by the image sensor 104 and produces a ghost image 332.

Thus, while the IR cut filter may block a large portion of the IR light, it may detrimentally produce a red secondary image called ghosting. This problem becomes serious when taking a picture of a bright object. For example, when a picture is taken that includes the sun, multiple ghost images of the sun in the red spectrum are produced. Ghosting can occur in both still camera images and video recorder images.

Some methods for reducing ghosting are disclosed in U.S. patent No. 7,038,722 to north-shore (Kitagishi). The method involves fabricating color filters within a Color Filter Array (CFA) of an image sensor to have a particular transmittance designed to match a particular IR cut filter. Thus, the image sensor is customized for a given CFA. In contrast, embodiments of the present disclosure describe techniques for reducing ghosting, which can be applied to almost any general image sensor in which the CFA does not have a specifically designed transmittance.

FIG. 4 illustrates an IR cut filter 400 including a transparent substrate 402 and an IR reflective film 404 according to an embodiment of the invention. Transparent substrate 402 is typically made of glass, but other materials such as polyester are also possible. An IR reflecting film 404 is disposed on the substrate 402 facing the imaging lens 102. The IR reflecting film 404 may be an interference filter formed from a single or multilayer coating. Light 110 from the object 108 passes through the lens 102 and is incident on the filter 400. Due to light interference, the IR component contained in the incident light 110 is reflected by the film 404. However, the IR reflecting film 404 does not completely transmit visible light from the incident light 110. Some visible light, especially red light near the IR spectrum, may be partially reflected by the IR reflective film 404 along with the IR light component to become reflected light 312. In other words, the reflection spectrum of the IR reflecting film 404 contains red light. The remainder of the incident light 110, which may contain less red light component and no IR light, is transmitted through the film 404 to become transmitted light 414.

The IR cut filter 400 further includes a red absorbing film 406 disposed on the opposite side of the substrate 402 facing the image sensor 104. The transmitted light 414 passes through the red absorbing film 406 and reaches the image sensor 104 at (a) for the first time. The transmitted light 414 is then partially reflected at the surface of the image sensor 104 to become reflected light 416, the reflected light 416 again passing through the red absorbing film 406 at (B) a second time. The red light contained in the reflected light 416 is then partially reflected by the IR reflective film 404 to become red reflected light 420. The remainder of the reflected light 416 passes through the IR reflecting film 404 to become transmitted light 418. The red reflected light 420 passes through the red absorbing film 406 again at (C) a third time. Three traverses of the red absorbing film 406 reduces the intensity of the red reflected light 420 to a substantially imperceptible level such that almost no secondary image is detected. Of course, the red absorbing film 406 does transmit some red light. If the red absorbing film 406 completely absorbs red light, the red primary image will not be detected. Thus, the red absorbing film 406 operates only to partially absorb the red light component, such that after three traverses of the film, the red light component is substantially removed.

In one embodiment, the red absorbing film 406 is essentially a cyan filter that partially absorbs/blocks red light and transmits green and blue light. Thus, any cyan color filter suitable for cyan, particularly cyan filters similar to cyan filters in a Color Filter Array (CFA) of a color image sensor, may be used. Further, a commercial cyan filter using a 50 micron thick dyed polyester film on a polyethylene terephthalate (PET) substrate, where the PET substrate serves as the transparent substrate 402 and the dyed polyester film serves as the red absorbing film 406, may also be used.

FIG. 5 illustrates an IR cut filter 500 according to an embodiment of the invention. The illustrated embodiment of the IR cut filter 500 includes an IR reflective film 504. The IR reflecting film 504 may be an interference filter formed from a single or multilayer coating. Light 110 from object 108 passes through lens 102 and is incident on filter 500. Due to light interference, the IR light component contained within the incident light 110 is reflected by the film 504. However, the IR reflecting film 504 does not completely transmit all visible light components of the incident light 110. Rather, some of the red light components near the IR spectrum may be partially reflected by the IR reflecting film 504 along with the IR light to become reflected light 312. In other words, the reflection spectrum of the IR reflecting film 504 includes red light. The remaining incident light 110, which may contain less red light components and little or no IR light components, is transmitted through the IR reflecting film 504 to become transmitted light 514.

The IR cut filter 500 further includes a red absorbing substrate 502. In the illustrated embodiment, an IR reflecting film 504 is disposed on the red absorbing substrate 502 facing the imaging lens 102. The transmitted light 514 passes through the red absorbing substrate 502 and reaches the image sensor 104 for the first time at (AA). The light 514 is then partially reflected at the surface of the image sensor 104 to become reflected light 516, the reflected light 516 passing through the red absorbing substrate 502 a second time at (BB). The red light contained in the reflected light 516 is partially reflected by the IR reflecting film 504 to become red reflected light 520. The remainder of the reflected light 516 passes through the IR reflecting film 504 to become transmitted light 518. The red reflected light 520 passes through the red absorbing substrate 502 a third time at (CC). Three passes through the red-absorbing substrate 502 substantially reduces the intensity of the red-reflected light 520 so that little or no ghost images are detected. Thus, the red absorbing substrate 502 only partially absorbs red light in order to pass the red primary image while sufficiently absorbing any red secondary image (ghost image).

In one embodiment, the red absorbing substrate 502 is a cyan filter that blocks red light and transmits green and blue light. Thus, a variety of cyan filters may be used, for example, colored glass filters. The colored glass is glass formed with a colorant mixed into the glass, as opposed to a colored film coated on the surface thereof. This is achieved by mixing various metal oxides in the glass composition. These colored glasses are commercially available from major glass manufacturers, such as schottky (schottky), Hoya (Hoya), and the like. Other colored substrates such as polyester are also possible.

FIG. 6 illustrates an IR cut filter 600 according to an embodiment of the invention. The illustrated embodiment of the IR cut filter 600 includes an IR reflecting film 604, a red absorbing substrate 602 similar to the red absorbing substrate 502, and a red absorbing film 606 similar to the red absorbing film 406. Thus, prior to forming the secondary image, incident light is absorbed three times by red absorbing substrate 602 at (AA), (BB) and (CC) and three times by red absorbing film 606 at (a), (B) and (C). Three passes through the red absorbing substrate 602 and three passes through the red absorbing film 606 substantially reduce the intensity of the red reflected light 620 to substantially eliminate ghosting.

Thus, the IR cut filter according to the illustrated embodiment includes an IR reflective film and a red absorbing layer, which may be implemented as a red absorbing substrate or a red absorbing film disposed on a transparent substrate. The IR cut filter may also include both a red absorbing substrate and a red absorbing film.

An embodiment of an IR reflective film may be an interference filter. The reflection spectrum of the interference filter extends from the IR spectrum into the red spectrum. Before any ghosting is formed, incident light is absorbed three times in the red absorbing layer, the first absorption occurring after transmission through the IR reflecting film, the second absorption occurring after reflection at the image sensor, and the third absorption occurring after reflection at the IR reflecting film.

Embodiments of the red absorbing layer may reduce the detected red intensity in the primary image, resulting in a bluish primary image. However, this problem may be addressed by adjusting the gain associated with each of the red, green, and blue signals, which may be done before (e.g., hardware logic) or after (e.g., post-image processing or hardware logic adjustment) the fabrication of the image sensor.

Fig. 7 illustrates an IR cut filter 700 according to another embodiment of the invention. The IR cut filter 700 is similar to the IR cut filter 500 (fig. 5), but further includes an AR film 706 disposed above the red absorbing substrate 502 toward the image sensor 104.

FIG. 8 illustrates an IR cut filter 800 according to another embodiment of the invention. The IR cut filter 800 is similar to the IR cut filter 400 (fig. 4), but further includes an AR film 806 disposed above the red absorbing film 406 toward the image sensor 104.

FIG. 9 illustrates an IR cut filter 900 according to another embodiment of the invention. The IR cut filter 900 is similar to the IR cut filter 600 (fig. 6), but further includes an AR film 906 disposed above the red absorbing film 606 toward the image sensor 104.

Fig. 10(a) illustrates an example of an IR cut filter 400 having a red absorbing layer 406. For example, the IR reflective film 404 can reflect 5% of the red light, thus 95% of the red light is transmitted through the IR reflective film 404. If the red absorbing layer 406 absorbs 10% of the red light, 85% of the red light will be incident on the image sensor 104. The pixel structure and surface of the image sensor 104 generate four reflected beams in different directions. Assuming a total reflected light of 4%, the reflected light beam is approximately 1%. After passing through the red absorbing layer 406 a second time, the red light is 0.9%. Next, 5% of 0.9% of the red light is reflected by the IR reflecting film 404. Thus, 0.045% of the original red light is reflected by the IR reflecting film 404. Finally, after passing through the red absorbing layer 406 a third time, only 0.0405% of the original red light remains.

In contrast, fig. 10(b) illustrates an example of the IR cut filter 300 without any red absorbing layer. After transmission through the IR reflecting film 304, the red light was 95%. After reflection at the image sensor 104, the red light is 1.1%. After reflection at the IR reflecting film 304, 0.055% of the red light remains. Thus, by using a single red absorbing layer with 10% absorption, the magnitude of red reflected light is reduced by more than 25%. The use of two red absorbing layers will reduce the reflected red light by more than 50%. To further reduce the magnitude of red reflected light, a red absorbing layer with a higher absorption coefficient (e.g., 20% or 30%) may be used.

Fig. 11 is a functional block diagram illustrating an imaging system 1100 according to an embodiment of the invention. The illustrated embodiment of imaging system 1100 includes a pixel array 1105, readout circuitry 1110, function logic 1115, and control circuitry 1120. The imaging system 1100 is one possible implementation of the image sensor 104 described above.

The pixel array 1105 is a two-dimensional ("2D") imaging sensor or pixel (e.g., pixels P1, P2, …, Pn) array. In one embodiment, each pixel is a complementary metal oxide semiconductor ("CMOS") imaging pixel. In other embodiments, each pixel may be implemented as a CCD. As illustrated, each pixel is arranged into a row (e.g., row R1-Ry) and a column (e.g., column C1-Cx) to acquire image data of a person, place, or object, which can then be used to render a 2D image of the person, place, or object.

After each pixel has acquired its image data or image charge, the image data is read out by readout circuitry 1110 and transferred to functional logic 1115. Readout circuitry 1110 may include amplification circuitry, analog-to-digital ("ADC") conversion circuitry, or others. Function logic 1115 may simply store the image data or even manipulate the image data by applying post-image effects (e.g., crop, rotate, remove red-eye, adjust brightness, adjust contrast, or otherwise). In one embodiment, readout circuitry 1110 may readout a row of image data at a time along readout column lines (illustrated) or may readout the image data using a variety of other techniques (not illustrated), such as serial readout, full parallel readout of all pixels simultaneously, or others.

The control circuitry 1120 is coupled to the pixel array 1105 to control operating characteristics of the pixel array 1105. For example, the control circuit 1120 may generate a shutter signal for controlling image acquisition. In one embodiment, the shutter signal is a global shutter signal for simultaneously enabling all pixels within pixel array 205 to simultaneously capture their respective image data during a single acquisition window. In an alternative embodiment, the shutter signal is a rolling shutter signal, whereby each row, column, or group of pixels is sequentially enabled during successive acquisition windows.

The above description of illustrated embodiments of the invention, including what is described in the Abstract of the disclosure, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. These modifications can be made to the invention in light of the above detailed description.

The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

Claims (22)

1. A camera apparatus, comprising:

an image sensor to capture image light and generate an image in response to the image light;

an imaging lens optically aligned with the image sensor to focus the image light onto the image sensor; and

an infrared cut filter disposed between the imaging lens and the image sensor to remove infrared light components from the image light before the image light reaches the image sensor, the infrared cut filter including:

at least one red absorbing layer that partially absorbs a red light component within the image light; and

an infrared reflector that reflects the infrared light component, the infrared reflector disposed on the red absorbing layer

And the imaging lens.

2. The camera apparatus of claim 1, wherein the at least one red absorbing layer comprises a red absorbing substrate, and wherein the infrared reflector comprises an infrared reflective film disposed on the red absorbing substrate facing the imaging lens.

3. The camera device of claim 2, wherein the red absorbing substrate comprises colored glass.

4. The camera apparatus of claim 2, wherein the at least one red absorbing layer further comprises a red absorbing film disposed on the red absorbing substrate and facing the image sensor.

5. The camera apparatus of claim 4, wherein the infrared cut filter further comprises an anti-reflection film disposed on the red absorbing film and facing the image sensor.

6. The camera apparatus of claim 2, wherein the infrared cut filter further comprises an anti-reflection film disposed between the at least one red absorption layer and the image sensor.

7. The camera apparatus of claim 1, wherein the infrared cut filter further comprises a substantially transparent substrate that is substantially colorless disposed between the at least one red absorbing layer and the infrared reflector.

8. The camera apparatus of claim 7, wherein the at least one red absorbing layer comprises a red absorbing film disposed on the substantially transparent substrate and facing the image sensor.

9. The camera apparatus of claim 8, wherein the infrared cut filter further comprises an anti-reflection film disposed on the red absorbing film and facing the image sensor.

10. The camera apparatus of claim 1, wherein the infrared reflector at least partially reflects at least a portion of the red light component within the image light such that multiple absorptions of reflected red light reduce red ghosting.

11. The camera device of claim 1, wherein the infrared reflector comprises a multilayer interference filter having a reflection spectrum extending from the infrared spectrum into a portion of the visible red spectrum.

12. An infrared cut filter for use with an image sensor to remove infrared light components from image light received from a first side of the infrared cut filter before the image light reaches the image sensor to be disposed on a second side of the infrared cut filter, the infrared cut filter comprising:

at least one red absorbing layer that partially absorbs a red light component within the image light; and

an infrared reflector that reflects the infrared light component,

wherein the infrared reflector is disposed between the red absorbing layer and the first side of the infrared cut filter,

wherein the at least one red absorbing layer is disposed between the infrared reflector and the second side of the infrared cut filter, the second side being opposite the first side.

13. The infrared cut filter of claim 12, wherein the at least one red absorbing layer comprises a red absorbing substrate, and wherein the infrared reflector comprises an infrared reflective film disposed on the red absorbing substrate between the red absorbing substrate and the first side of the infrared cut filter.

14. The infrared cut-off filter of claim 13, wherein the red absorbing substrate comprises colored glass.

15. The infrared cut filter of claim 13, wherein the at least one red absorbing layer further comprises a red absorbing film disposed on the red absorbing substrate between the red absorbing substrate and the second side of the infrared cut filter.

16. The infrared cut filter of claim 15, wherein the infrared cut filter further comprises an anti-reflective film disposed on the red absorbing film between the red absorbing film and the second side of the infrared cut filter.

17. The infrared cut-off filter of claim 12, wherein the infrared cut-off filter further comprises a substantially transparent substrate that is substantially colorless disposed between the at least one red absorbing layer and the infrared reflector.

18. The infrared cut-off filter of claim 17, wherein the at least one red absorbing layer comprises a red absorbing film disposed on the substantially transparent substrate between the substantially transparent substrate and the second side of the infrared cut-off filter.

19. The infrared cut filter of claim 18, wherein the infrared cut filter further comprises an anti-reflective film disposed on the red absorbing film between the red absorbing film and a second side of the infrared cut filter.

20. The infrared cut-off filter of claim 12, wherein the infrared reflector at least partially reflects at least a portion of the red light component within the image light such that multiple absorptions of reflected red light reduce red ghosting.

21. The infrared cut filter of claim 12 wherein the infrared reflector comprises a multilayer interference filter having a reflection spectrum extending from the infrared spectrum into a portion of the visible red spectrum.

22. The infrared cut filter of claim 12, wherein the at least one red absorbing layer comprises a cyan filter.