Optical system and optical combination

Abstract

An optical system includes an extended illumination source configured to emit light from an extended emission surface thereof toward a display panel. The emitted light includes substantially distinct blue, green, and red emission spectra having respective blue, green, and red peaks at respective blue, green, and red peak wavelengths and corresponding blue, green, and red full-widths at half-maximum (FWHMs). The blue FWHM extends from a smaller blue wavelength to a longer blue wavelength. The optical system also includes a reflective polarizer disposed on the emission surface of the extended illumination source. The reflective polarizer includes a plurality of first polymer layers. The optical system also includes a light filter disposed between the reflective polarizer and the emission surface of the extended illumination source.

Description

Technical Field

[0001] This disclosure relates generally to an optical system, and more particularly to an optical system and optical assembly for a backlight. Background Technology

[0002] A backlight unit is used to provide light to a display panel. A backlight unit typically includes one or more light sources that emit light. In some cases, the backlight unit may emit low-wavelength blue light and / or ultraviolet (UV) light that may be harmful to viewers. Summary of the Invention

[0003] In a first aspect, this disclosure provides an optical system. The optical system includes an extended illumination source configured to emit light from its extended emitting surface toward a display panel. The emitted light includes substantially different blue, green, and red emission spectra, each having a corresponding blue peak, green peak, and red peak at a corresponding blue peak wavelength, green peak wavelength, and red peak wavelength, and corresponding full width at half maximum (FWHM) for blue, green, and red light, respectively. The blue FWHM extends from a shorter blue light wavelength to a longer blue light wavelength. The optical system also includes a reflective polarizer disposed on the emitting surface of the extended illumination source. The reflective polarizer includes a plurality of first polymer layers totaling at least 10. The optical system also includes a filter disposed between the reflective polarizer and the emitting surface of the extended illumination source. The filter includes a plurality of second polymer layers totaling at least 10. Each of the first polymer layer and the second polymer layer has an average thickness of less than about 300 nanometers (nm). For substantially perpendicular incident light, and for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, the plurality of first polymer layers reflect more than about 60% of the incident light having a first polarization state and transmit more than about 60% of the incident light having an orthogonal second polarization state. For substantially perpendicular incident light, for each of the green peak wavelength and the red peak wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit more than about 70% of the incident light. For substantially perpendicular incident light, for the smaller blue wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit less than about 60% of the incident light.

[0004] In a second aspect, this disclosure provides another optical system. The optical system includes an extended illumination source configured to emit light from its extended emitting surface toward a display panel. The emitted light includes substantially different blue, green, and red emission spectra, each having a corresponding blue peak, green peak, and red peak at a corresponding blue peak wavelength, green peak wavelength, and red peak wavelength, and corresponding full width at half maximum (FWHM) for blue, green, and red light, respectively. The blue FWHM extends from a shorter blue light wavelength to a longer blue light wavelength. The optical system also includes a reflective polarizer disposed on the emitting surface of the extended illumination source. The reflective polarizer includes a plurality of first polymer layers totaling at least 10. The optical system also includes a filter disposed between the reflective polarizer and the emitting surface of the extended illumination source. The filter includes a plurality of second polymer layers totaling at least 10. Each of the first polymer layer and the second polymer layer has an average thickness of less than about 300 nm. For substantially perpendicular incident light, and for each of the blue light peak wavelength, the green light peak wavelength, and the red light peak wavelength, the plurality of first polymer layers reflect more than about 60% of the incident light having a first polarization state and transmit more than about 60% of the incident light having an orthogonal second polarization state. For substantially perpendicular incident light, for each of the green light peak wavelength and the red light peak wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit more than about 70% of the incident light. For substantially perpendicular incident light, and for each of the first polarization state and the second polarization state, the transmittance of the plurality of second polymer layers at the shorter blue light wavelength is at least 30% less than the transmittance at the longer blue light wavelength.

[0005] In a third aspect, this disclosure provides an optical assembly. The optical assembly includes a reflective polarizer having a plurality of first polymer layers, totaling at least 10. Each of the first polymer layers has an average thickness of less than about 300 nm. The optical assembly also includes a filter configured to be in optical communication with the reflective polarizer. The filter includes a plurality of second polymer layers, totaling at least 10, disposed between opposing outermost polymer layers. Each opposing outermost polymer layer and each second polymer layer between them has an average thickness of less than about 300 nm. The thinnest second polymer layer among the plurality of second polymer layers is disposed between and spaced apart from the opposing outermost polymer layers. For substantially perpendicular incident light and a blue light wavelength range extending from about 430 nm to about 480 nm, a green light wavelength range extending from about 500 nm to about 570 nm, and a red light wavelength range extending from about 600 nm to about 680 nm, and for at least one wavelength within each of the blue light wavelength range, the green light wavelength range, and the red light wavelength range, the plurality of first polymer layers reflect more than about 60% of the incident light having a first polarization state and transmit more than about 60% of the incident light having an orthogonal second polarization state. For substantially perpendicular incident light and the blue light wavelength range extending from about 430 nm to about 480 nm, the green light wavelength range extending from about 500 nm to about 570 nm, and the red light wavelength range extending from about 600 nm to about 680 nm, and for each of the first polarization state and the second polarization state, for the at least one wavelength within each of the green light wavelength range and the red light wavelength range, the plurality of second polymer layers transmit more than about 70% of the incident light. For the substantially perpendicular incident light and the blue light wavelength range extending from about 430 nm to about 480 nm, the green light wavelength range extending from about 500 nm to about 570 nm, and the red light wavelength range extending from about 600 nm to about 680 nm, for the ultraviolet (UV) wavelength range extending from about 410 nm to about 420 nm, and for the second polarization state, the plurality of first polymer layers have an average transmittance T1 and the plurality of second polymer layers have an average transmittance T2, T1 / T2 ≥ 1.5.

[0006] In a fourth aspect, this disclosure provides another optical system. The optical system includes an extended illumination source configured to emit light from its extended emitting surface toward a display panel. The emitted light includes a blue light emission spectrum having a blue light peak at a blue light peak wavelength and a corresponding full width at half maximum (FWHM) extending from a shorter blue light wavelength to a longer blue light wavelength. The optical system also includes an optical assembly disposed on the emitting surface of the extended illumination source. The optical assembly includes a reflective polarizer having a plurality of first polymer layers totaling at least 10. The optical assembly also includes a filter disposed between the reflective polarizer and the emitting surface of the extended illumination source. The filter includes a plurality of second polymer layers totaling at least 10. Each of the first and second polymer layers has an average thickness of less than about 300 nm. For substantially perpendicular incident light, and for the peak wavelength of the blue light, the optical assembly reflects more than about 70% of the incident light having a first polarization state, and has a transmittance S1 of more than about 30% for an orthogonal second polarization state. For substantially perpendicular incident light, and for the smaller blue light wavelength, the optical assembly reflects more than about 70% of the incident light having the first polarization state, and has a transmittance S2 for the second polarization state, S2 being at least 10% smaller than S1.

[0007] In a fifth aspect, this disclosure provides another optical system. This optical system includes an extended illumination source configured to emit light from its extended emitting surface toward a display panel. The emitted light includes substantially different blue, green, and red emission spectra, each having a corresponding blue peak, green peak, and red peak at a corresponding blue peak wavelength, green peak wavelength, and red peak wavelength, and corresponding full width at half maximum (FWHM) for blue, green, and red light, respectively. The blue FWHM extends from a shorter blue light wavelength to a longer blue light wavelength. The optical system also includes a filter disposed on the emitting surface of the extended illumination source. The filter comprises at least 10 polymer layers in total. Each polymer layer has an average thickness of less than about 300 nm. For substantially perpendicular incident light, for each of the green peak wavelength and the red peak wavelength, and for each of the first polarization state and the orthogonal second polarization state, the plurality of polymer layers transmit more than about 70% of the incident light. For substantially perpendicular incident light, for the smaller blue wavelength, and for each of the first polarization state and the second polarization state, the plurality of polymer layers transmit less than about 60% of the incident light. Attached Figure Description

[0008] The exemplary embodiments disclosed herein can be more fully understood in light of the following detailed description taken in conjunction with the accompanying drawings. The drawings are not necessarily drawn to scale. Similar numbers used in the drawings refer to similar parts. However, it should be understood that the use of numbers to refer to parts in a given drawing is not intended to limit parts labeled with the same numbers in another drawing.

[0009] Figure 1 This is a schematic exploded view of an optical system according to one embodiment of the present disclosure;

[0010] Figure 2A It is based on one implementation scheme of this disclosure. Figure 1 A schematic exploded view of the illumination source of the optical system shown;

[0011] Figure 2B It is based on one implementation scheme of this disclosure. Figure 2A The lighting source shown and Figure 1 An exploded schematic diagram of the filter in the optical system shown.

[0012] Figure 3 It is based on another embodiment of this disclosure. Figure 1 A schematic exploded perspective view of the illumination source of the optical system shown;

[0013] Figure 4 It is based on one implementation scheme of this disclosure. Figure 1 A detailed schematic diagram of the reflective polarizer of the optical system shown.

[0014] Figure 5 It is based on one implementation scheme of this disclosure. Figure 1 A detailed schematic diagram of the filter in the optical system shown;

[0015] Figure 6 This illustrates one embodiment according to the present disclosure. Figure 3 The graph shows the relationship between the number of filter layers and the average thickness.

[0016] Figure 7 This is a graph showing the relationship between the transmittance of the reflective polarizer and filter of an optical system according to one embodiment of the present disclosure and the wavelength;

[0017] Figure 8 This is another graph showing the relationship between the transmittance of the reflective polarizer and filter of an optical system according to another embodiment of the present disclosure and the wavelength; and

[0018] Figure 9 This illustrates one embodiment according to the present disclosure. Figure 1 The graph shows the relationship between the transmittance and wavelength of the optical system's optical assembly. Detailed Implementation

[0019] In the following description, reference is made to the accompanying drawings, which form a part thereof, and various embodiments are illustrated therein. It should be understood that other embodiments can be conceived and made without departing from the scope or spirit of this disclosure. Therefore, the following detailed description should not be considered limiting.

[0020] This disclosure relates to an optical system. This optical system can be used in the backlight of electronic devices including displays, such as computer monitors, televisions, mobile phones, personal digital assistants (PDAs), wearable devices, and other portable devices.

[0021] Backlights can emit ultraviolet (UV) light and low-wavelength blue light. UV and blue light can be harmful to the human eye and may potentially cause macular degeneration. Traditional electronic displays include light-absorbing dyes to block certain harmful wavelengths. However, these dyes typically have broad absorption bands. In other words, they can absorb light over a relatively long range of wavelengths, resulting in undesirable color shifts.

[0022] This disclosure relates to an optical system. The optical system includes an extended illumination source configured to emit light from its extended emitting surface toward a display panel. The emitted light includes substantially different blue, green, and red emission spectra, each having a corresponding blue peak, green peak, and red peak at a corresponding blue peak wavelength, green peak wavelength, and red peak wavelength, and corresponding full width at half maximum (FWHM) for blue, green, and red light, respectively. The blue FWHM extends from a shorter blue light wavelength to a longer blue light wavelength. The optical system also includes a reflective polarizer disposed on the emitting surface of the extended illumination source. The reflective polarizer includes a plurality of first polymer layers. The optical system also includes a filter disposed between the reflective polarizer and the emitting surface of the extended illumination source. The filter includes a plurality of second polymer layers. For substantially perpendicular incident light, and for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, the plurality of first polymer layers reflect more than about 60% of the incident light having a first polarization state and transmit more than about 60% of the incident light having an orthogonal second polarization state. For substantially perpendicular incident light, for each of the green peak wavelength and the red peak wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit more than about 70% of the incident light. For substantially perpendicular incident light, for the smaller blue wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit less than about 60% of the incident light.

[0023] For this smaller blue light wavelength range, the filter of this disclosure can have relatively low transmittance, independent of the polarization of the incident light. Therefore, for each of the first and second polarization states, the optical system including the filter can have overall low transmittance for this smaller blue light wavelength range. This protects the viewer from the harmful effects of low-wavelength blue light in the wavelength range of approximately 400 nanometers (nm) to approximately 430 nm. Furthermore, the filter has relatively high transmittance for green and red light. In some cases, the filter has high transmittance across the entire visible spectrum, in addition to the low blue light wavelength range. Therefore, the filter may not provide undesirable color shift. The optical system including the filter can exhibit high efficiency and minimal color shift.

[0024] In some cases, the filter may also have relatively low transmittance for the ultraviolet (UV) wavelength range, extending from about 410 nm to about 420 nm, compared to the reflective polarizer. Therefore, the optical system including the filter can essentially block light in this UV wavelength range and protect the viewer from UV light.

[0025] The present disclosure discloses a reflective polarizer and a filter together to form an optical assembly. For substantially perpendicular incident light, and for the peak wavelength of the blue light, the optical assembly reflects more than about 70% of the incident light having the first polarization state, and has a transmittance S1 greater than about 30% for the second polarization state. For the smaller blue light wavelength, the optical assembly reflects more than about 70% of the incident light having the first polarization state, and has a transmittance S2 for the second polarization state, such that S2 is at least 10% smaller than S1. Therefore, the optical assembly can provide a transition from substantially reflective or blocking light (e.g., transmittance <10% at 420 nm) to substantially transmissive light (e.g., transmittance >50% at 440 nm) within a relatively narrow wavelength range of about 15 nm to about 20 nm. Thus, for the second polarization state, the optical assembly can provide a strong transmission band with a sharp band edge required to achieve color-balanced white transmission, while blocking smaller blue light wavelengths. The reflective polarizer and the filter enable the optical system to essentially block low-wavelength blue light in a narrow band. Therefore, this combination of reflective polarizer and filter of the present disclosure exhibits superior performance in reducing the transmittance of smaller blue light wavelengths in the visible spectrum, while providing minimal color shift.

[0026] Each of the reflective polarizer and the filter comprises a plurality of first polymer layers and a plurality of second polymer layers. The aforementioned desired characteristics of the filter and the reflective polarizer are achieved through various factors, such as the appropriate material selection of the polymer layers, the thickness of the polymer layers, and the number of polymer layers.

[0027] Now for reference Figure 1 The diagram illustrates an optical system 500 according to one embodiment of the present disclosure. The optical system 500 defines mutually orthogonal x-axis, y-axis, and z-axis. The x-axis and y-axis are in-plane axes of the optical system 500, while the z-axis is a transverse axis disposed along the thickness of the optical system 500. In other words, the x-axis and y-axis are disposed along the plane of the optical system 500, while the z-axis is perpendicular to the plane of the optical system 500.

[0028] The optical system 500 includes an extended illumination source 10, a reflective polarizer 40, a filter 50, and a display panel 30. The reflective polarizer 40, the filter 50, and the display panel 30 are disposed adjacent to each other along the z-axis. For example, in some embodiments, the reflective polarizer 40 and the filter 50 are bonded together by means of optical adhesives, epoxy resins, lamination, or any other suitable attachment method. In the illustrated embodiment, the reflective polarizer 40 is disposed between the filter 50 and the display panel 30.

[0029] Extended illumination source 10 defines an extended emitting surface 11 and a bottom surface 16 opposite to the extended emitting surface 11. Extended illumination source 10 is configured to emit light 20 from its extended emitting surface 11 to display panel 30. In some embodiments, display panel 30 includes an organic light-emitting diode (OLED) display panel. In some other embodiments, display panel 30 includes a liquid crystal display (LCD) panel.

[0030] The light 20 emitted from the display panel 30 is typically unpolarized light. However, in some cases, the light 20 may be at least partially polarized light. For illustrative purposes, the light 20 may be considered as light having an unknown or arbitrary polarization state or polarization state distribution. Furthermore, the reflecting polarizer 40 reflects the light 20 having a first polarization state along the x-axis. The reflecting polarizer 40 transmits the light 20 having a second orthogonal polarization state along the y-axis.

[0031] Optionally, the optical system 500 further includes a light conversion layer 36 disposed adjacent to the extended emitting surface 11 of the extended illumination source 10. The light conversion layer 36 converts at least a portion of light 20 into light 17. Light 17 may have a wavelength distribution different from that of light 20. In some embodiments, for at least a first wavelength, the light conversion layer 36 converts at least a portion of light 20 into light 17 having at least a second wavelength different from the first wavelength. For example, the light conversion layer 36 may convert blue light into green or red light. In some embodiments, the light conversion layer 36 alters or converts the light 20 emitted from the extended illumination source 10 into white light, i.e., light 17. Furthermore, the light conversion layer 36 may emit white light toward the filter 50. In some embodiments, the light conversion layer 36 comprises a semiconductor material, such as a semiconductor nanocrystal. The light conversion layer 36 can provide, but is not limited to, significantly improved color reproduction and color purity. In some embodiments, the semiconductor nanocrystal may be formed of at least one of group II-VI compound semiconductor materials, group III-V compound semiconductor materials, or group IV semiconductor materials. In some implementations, the light conversion layer 36 may include multiple layers.

[0032] The optical system 500 also includes at least one diffuser 32 disposed between the light conversion layer 36 and the filter 50. Figure 1 In the illustrated embodiment, the optical system 500 includes two diffusers 32. One diffuser 32 is disposed adjacent to the light conversion layer 36, and the other diffuser 32 is disposed adjacent to the filter 50. In some other embodiments, the optical system 500 may include only one diffuser 32. The diffuser 32 diffuses the light 17 emitted from the light conversion layer 36. Specifically, the diffuser 32 may spatially expand the light 17 received from the light conversion layer 36. The diffuser 32 may comprise a diffuser film or plate made of any one or more suitable scattering materials. In some embodiments, the diffuser 32 may be disposed directly on the light conversion layer 36. The diffuser 32 may diffuse the incoming light to make the light intensity more uniform in space. The intensity of light from one or more point sources may be much greater at a specific location on the incident surface of the diffuser 32. However, the intensity of light emitted from the diffuser 32 may be more uniform across the entire exit surface of the diffuser 32.

[0033] Continue to refer to Figure 1The optical system 500 also includes a prism film 34 disposed between diffusers 32. The prism film 34 includes two intersecting prism layers 35 disposed adjacent to each other. Each prism layer 35 includes a plurality of prism structures 34a forming ridges. Furthermore, the prism structures 34a of the prism layers 35 may be tilted relative to each other. Specifically, the prism structures 34a of the prism layers 35 may be substantially orthogonal to each other. Depending on the angle of incidence of light received from the diffusers 32, light may pass through the prism film 34, or light may be redirected back to the diffusers 32. The redirected light can then be recycled. The prism film 34 can increase the coaxial brightness of the optical system 500 and thus can act as a brightening layer. Examples of prism films 34 include Vikuiti, available from 3M Company. TM The brand's Brightening Enhancement Film (BEF). Alternatively, the Prism Film 34 may include Vikuiti, also available from 3M. TM The brand's Transmissive Right Angle Film (TRAF).

[0034] In some embodiments, the light conversion layer 36, diffuser 32, prism film 34, filter 50, reflective polarizer 40, and display panel 30 are substantially colinear with each other or have the same in-plane dimensions (i.e., length and width). Specifically, the light conversion layer 36, diffuser 32, prism film 34, filter 50, reflective polarizer 40, and display panel 30 may be substantially colinear with each other in the xy plane. Furthermore, the light conversion layer 36, diffuser 32, prism film 34, filter 50, reflective polarizer 40, and display panel 30 are disposed adjacent to each other along the z-axis of the optical system 500. In some embodiments, the optical system 500 may also include an absorptive polarizing film disposed between the extended illumination source 10 and the display panel 30.

[0035] In some implementations, the optical system 500 may include additional or intermediate films, layers, or components, such as a steering layer or substrate layer. The optical system 500 may have any suitable thickness overall, depending on the desired application properties.

[0036] Figure 2A An extended lighting source 10' according to one embodiment of the present disclosure is shown. The extended lighting source 10' can be used as... Figure 1The extended illumination source 10 is shown. The extended illumination source 10' includes a reflective layer 70, a first optical diffuser layer 80, and at least one light source 12. The first optical diffuser layer 80 is disposed on the reflective layer 70 for scattering light 13 and includes an extended emitting surface 11'. The first optical diffuser layer 80 and the reflective layer 70 are substantially co-linear in length and width and define an optical cavity 90 therebetween. Specifically, the first optical diffuser layer 80 and the reflective layer 70 are substantially co-linear in the xy plane. At least one light source 12 is disposed in the optical cavity 90. In some embodiments, at least one light source 12 is a visible light source. The first optical diffuser layer 80 may increase the uniformity of the light 13 received from the light source 12. In some embodiments, the light source 12 may include at least one of an incandescent or arc lamp, a light-emitting diode (LED), a linear cold cathode fluorescent lamp, a nonlinear cold cathode fluorescent lamp, a flat fluorescent panel, or an external electrode fluorescent lamp.

[0037] Figure 2B An extended illumination source 10' according to one embodiment of the present disclosure and a filter 50 disposed on the extended illumination source 10' are shown. Specifically, the filter 50 is disposed adjacent to the extended emitting surface 11' of the extended illumination source 10'. In some embodiments, the filter 50 and the extended emitting surface 11 are attached by one or more of pressure-sensitive adhesives, optically clear adhesives, ultraviolet (UV) curable adhesives, polyvinyl alcohol-based adhesives, and laminations. In some embodiments, the light source 12 includes an organic light-emitting diode (OLED). Therefore, the filter 50 and the extended illumination source 10' are configured to be in direct optical communication with each other.

[0038] Figure 3 An extended lighting source 10 is shown according to another embodiment of this disclosure. The extended lighting source 10 can be used as... Figure 1The extended illumination source 10 is shown. The extended illumination source 10” includes a light guide 100 for propagating light 14 therein along its length (i.e., x-axis) and width (i.e., y-axis). The light guide 100 is disposed between the back reflector 110 and the extended emitting surface 11”. The extended illumination source 10” also includes at least one light source 15a, 15b disposed adjacent to the edge surfaces 110a, 110b of the light guide 100. In the illustrated embodiment, the light sources 15a, 15b are arranged in a side-light configuration adjacent to the respective edge surfaces 110a, 110b of the light guide 100. A back reflector 110 is configured to reflect light 14a emitted from the light guide 100 toward the back reflector 110. Furthermore, the back reflector 110 is configured to reflect light 14a as reflected light 14b. The reflected light 14b exits the extended illumination source 10” through the extended emitting surface 11”. In some embodiments, the light sources 15a, 15b are visible light sources. In some embodiments, the light sources 15a, 15b may include at least one of an incandescent or arc lamp, a light-emitting diode (LED), a linear cold cathode fluorescent lamp, a nonlinear cold cathode fluorescent lamp, a flat fluorescent panel, or an external electrode fluorescent lamp.

[0039] Continue to refer to Figure 3 The extended illumination source 10” also includes a second optical diffuser layer 120 disposed on the light guide 100. The second optical diffuser layer 120 includes an extended emitting surface 11”. The second optical diffuser layer 120 can increase the uniformity of the light 14b received through the light guide 100.

[0040] Figure 4 A schematic diagram of a reflective polarizer 40 according to one embodiment of the present disclosure is shown. In some cases, the reflective polarizer 40 may include one or more of a polymer reflective polarizer, a wire grid reflective polarizer, and a diffuse reflective polarizer. Reference Figure 1 and Figure 4 The reflective polarizer 40 is disposed on the emitting surface 11 of the extended illumination source 10 and includes a plurality of first polymer layers 41, 42, totaling at least 10. Specifically, as Figure 1As shown, the reflective polarizer 40 is disposed on the emitting surface 11 of the extended illumination source 10 and adjacent to the display panel 30. First polymer layers 41 and 42 are arranged alternately along the thickness (i.e., z-axis) direction of the reflective polarizer 40. In some embodiments, the total number of the plurality of first polymer layers 41 and 42 is at least 30, at least 40, at least 50, at least 70, at least 100, at least 200, or at least 300. In some embodiments, each of the first polymer layers 41 comprises a high refractive index optical material (HIO) of polyethylene naphthalate (PEN). In some embodiments, each of the first polymer layers 41 comprises a high refractive index optical material (HIO) of low-melting-point PEN. In some embodiments, each of the first polymer layers 42 comprises a low refractive index optical material (LIO) of a copolymer of polyethylene terephthalate (CoPET), CoPEN, or a blend of polycarbonate and CoPET.

[0041] Figure 5 A schematic diagram of a filter 50 according to one embodiment of the present disclosure is shown. (Reference) Figure 1 and Figure 5 The filter 50 is disposed between the reflective polarizer 40 and the emitting surface 11 of the extended illumination source 10, and includes a plurality of second polymer layers 51, 52, totaling at least 10 in number. Figure 1 As shown, filter 50 is disposed adjacent to reflective polarizer 40. Second polymer layers 51 and 52 are arranged alternately along the thickness (i.e., z-axis) direction of filter 50. In some embodiments, the total number of the plurality of second polymer layers 51 and 52 is at least 30, at least 40, at least 50, at least 70, at least 100, at least 200, at least 300, or at least 400. Second polymer layers 51 and 52 may comprise materials comprising polystyrene (PS) and / or poly(methyl methacrylate) (PMMA) copolymers. In some embodiments, each of the second polymer layers 51 comprises a high refractive index optical layer (HIO) of polyethylene terephthalate (PET) homopolymer (100 mol% terephthalic acid and 100 mol% ethylene glycol) having a glass transition temperature (Tg) of about 81 degrees Celsius (°C) to about 83 degrees Celsius. In some embodiments, each of the second polymer layers 52 comprises a low-refractive-index optical layer (LIO) of poly(methyl methacrylate) copolymer (also known as coPMMA) under the trade name OPTIX, which is available from Plaskolite, Columbus, Ohio, and has a Tg of about 80°C.

[0042] Furthermore, the second polymer layers 51 and 52 are interchangeably referred to as polymer layers 51 and 52.

[0043] refer to Figure 4 and Figure 5 Each of the first polymer layers 41, 42 and the second polymer layers 51, 52 has an average thickness “t1” and “t2”. Specifically, each of the first polymer layers 41, 42 defines an average thickness “t1” along the z-axis. Furthermore, each of the second polymer layers 51, 52 defines an average thickness “t2” along the z-axis. The term “average thickness” as used herein refers to the average thickness along a plane of the layer. Figure 4 and Figure 5 In the illustrated embodiments, the average thickness is measured along the xy-plane. In some embodiments, each of the first polymer layers 41, 42 and the second polymer layers 51, 52 has an average thickness “t1”, “t2” of less than about 300 nanometers (nm). In other words, each of the average thicknesses “t1”, “t2” may be less than about 300 nm. In some embodiments, each of the first polymer layers 41, 42 and the second polymer layers 51, 52 may have an average thickness “t1”, “t2” of less than about 250 nm, less than about 200 nm, less than about 150 nm, less than about 100 nm, or less than about 80 nm. In some embodiments, each of the average thicknesses “t1”, “t2” is at least about 50 nm.

[0044] refer to Figure 1 The optical system 500 also includes an optical assembly 600. In some embodiments, the optical assembly 600 is disposed on the emitting surface 11 of the extended illumination source 10. Specifically, the optical assembly 600 is disposed between the extended illumination source 10 and the display panel 30. The optical assembly 600 is disposed adjacent to the display panel 30. The optical assembly 600 includes a reflective polarizer 40 and a filter 50. The filter 50 is configured to be in optical communication with the reflective polarizer 40. As described above, the filter 50 is disposed between the reflective polarizer 40 and the emitting surface 11. In some embodiments, the reflective polarizer 40 and the filter 50 of the optical assembly 600 are attached to each other by one or more of pressure-sensitive adhesives, optically transparent adhesives, ultraviolet (UV) curable adhesives, polyvinyl alcohol-based adhesives, and laminations. However, the reflective polarizer 40 and the filter 50 can be attached to each other by any suitable attachment method based on the desired application properties. Figure 1In the illustrated embodiment, the reflective polarizer 40 and the filter 50 are arranged adjacent to each other. In some embodiments, the reflective polarizer 40 and the filter 50 are spaced apart from each other, such that the reflective polarizer 50 and the filter 50 are arranged in optical communication with each other. However, it should be noted that the filter 50 can be located anywhere between the reflective polarizer and the emitting surface 11 of the extended illumination source 10. In some embodiments, each of the reflective polarizer 40 and the filter 50 in the optical assembly 600 can be substantially flat and arranged along the xy plane. Reference Figure 1 , Figure 4 and Figure 5 In some embodiments, the reflective polarizer 40 of the optical assembly 600 includes a plurality of first polymer layers 41, 42, and the filter 50 of the optical assembly 600 includes a plurality of second polymer layers 51, 52.

[0045] Figure 6 An exemplary graph 650 is shown, illustrating the variation in thickness with the number of second polymer layers 51, 52 in the filter 50. (As described above...) Figure 1 and Figure 5 The filter 50 is configured to be optically connected to the reflective polarizer 40 and includes a plurality of second polymer layers 51, 52, totaling at least 10 in number. Figure 5 In the illustrated embodiment, a plurality of second polymer layers 51, 52 are disposed between opposing outermost polymer layers 53a, 53b. Each opposing outermost polymer layer 53a, 53b and each second polymer layer 51, 52 therebetween has an average thickness “t2” of less than about 300 nm. The opposing outermost polymer layers 53a, 53b may serve as protective layers for the filter 50. For example, the opposing outermost polymer layers 53a, 53b may serve as protective boundary layers (PBLs) for the filter 50.

[0046] Graph 650 shows the curves relating the average thickness "t2" of the second polymer layers 51, 52 to the number of layers in different configurations or designs of the filter 50. The outermost polymer layer 53a is designated as having a layer number of 0. The layer number increases sequentially from the outermost polymer layer 53a to the outermost polymer layer 53b. The outermost polymer layer 53b has the highest layer number. Therefore, the second polymer layers 51, 52 disposed between the opposing outermost polymer layers 53a, 53b have a layer number greater than 0 and less than the highest layer number corresponding to the outermost polymer layer 53b.

[0047] In some embodiments, the thinnest second polymer layer 53c among a plurality of second polymer layers 51, 52 is disposed between and spaced apart from the opposing outermost polymer layers 53a, 53b. Furthermore, each configuration of the filter 50 may have a maximum number of layers of approximately 1000. Additionally, the thickness “t2” may be from approximately 50 nm to approximately 80 nm.

[0048] exist Figure 6 In the examples shown, curve 652 represents the relationship between the average thickness "t2" and the number of second polymer layers 51 and 52 for a first design of filter 50. Curve 654 represents the relationship between the average thickness "t2" and the number of second polymer layers 51 and 52 for a second design of filter 50. Curve 656 represents the relationship between the average thickness "t2" and the number of second polymer layers 51 and 52 for a third design of filter 50. Curve 658 represents the relationship between the average thickness "t2" and the number of second polymer layers 51 and 52 for a fourth design of filter 50. In each of curves 652, 654, 656, and 658, the average thickness "t2" decreases significantly from the outermost polymer layer 53a to the thinnest second polymer layer 53c. The average thickness "t2" increases significantly from the thinnest second polymer layer 53c. The number of layers in the thinnest second polymer layer 53c is greater than 0 and less than the highest number of layers. Figure 6 In the example shown, the thinnest second polymer layer 53c has approximately 35 layers. Therefore, the thinnest second polymer layer 53c may be adjacent to the outermost polymer layer 53a. However, in some other cases, the thinnest second polymer layer 53c may be adjacent to the outermost polymer layer 53b. The thinnest second polymer layer 53c may have the smallest average thickness among the second polymer layers 51 and 52 of the filter 50. Furthermore, the minimum average thickness of the thinnest second polymer layer 53c may correspond to the minimum value in the corresponding curve of the relationship between average thickness and number of layers.

[0049] The variation of the average thickness "t2" of the second polymer layers 51 and 52 with the number of layers can be referred to as the layer thickness gradient of filter 50.

[0050] Figure 7 and Figure 8 Exemplary graphs 700 and 800 are shown respectively. Graphs 700 and 800 depict the reflective polarizer 40 and the filter 50 (e.g., ...). Figure 1 The graph shows the relationship between the percentage of transmission for different transmission spectra and wavelength. Wavelength is expressed in nanometers (nm) on the horizontal axis. Figure 7 and Figure 8 In the diagram, transmittance is expressed as the percentage of transmission on the left vertical axis. Reflectance is expressed as the percentage of reflection on the right vertical axis. The percentage of reflection and the percentage of transmission are complementary, i.e., percentage of reflection = (100 - percentage of transmission).

[0051] refer to Figure 1 and Figure 7 In some embodiments, the emitted light 20 includes a blue light emission spectrum 21b, which includes a blue light peak 22b at the blue light peak wavelength 23b and a corresponding blue light full width at half maximum (FWHM) 24b. The blue light FWHM 24b extends from a shorter blue light wavelength 25b1 to a longer blue light wavelength 25b2. The emitted light 20 also includes substantially different green light emission spectra 21g and red light emission spectra 21r, which include corresponding green light peaks 22g and red light peaks 22r at the corresponding green light peak wavelengths 23g and 23r, and corresponding green light FWHM 24g and red light FWHM 24r. Therefore, the emitted light 20 includes substantially different blue light emission spectra 21b, green light emission spectra 21g, and red light emission spectra 21r, which include corresponding blue light peaks 22b, green light peaks 22g, and red light peaks 22r at corresponding blue light peak wavelengths 23b, 23g, and 23r, and corresponding blue light FWHM 24b, green light FWHM 24g, and red light FWHM 24r. Figure 7 In the illustrated embodiment, substantially different blue light emission spectra 21b, green light emission spectra 21g, and red light emission spectra 21r can together form the total emission spectrum of the extended illumination source 10. The blue light emission spectrum 21b, green light emission spectrum 21g, and red light emission spectrum 21r of the extended illumination source 10 can be shown in graph 700 using any suitable energy unit.

[0052] As shown in graph 700, the shorter blue light wavelength 25b1 is approximately 430 nm, and the longer blue light wavelength 25b2 is approximately 460 nm. The peak wavelengths of blue light 23b, green light 23g, and red light 23r are approximately 445 nm, 530 nm, and 630 nm, respectively.

[0053] In some embodiments, the first polarization state is a p-polarization state and the second polarization state is an s-polarization state. In some other embodiments, the first polarization state is an s-polarization state and the second polarization state is a p-polarization state. The first polarization state is approximately along the x-axis and the second polarization state is approximately along the y-axis.

[0054] refer to Figure 4 and Figure 7In some embodiments, for substantially perpendicular incident light 60 and for a first polarization state, the reflective polarizer 40 includes a reflective spectrum 44. The reflective polarizer 40 may be at least partially transmissive in at least a portion of the reflective spectrum 44. Specifically, the reflective spectrum 44 includes a transmission band 44a. The free wave height (FWHM) of the transmission band 44a may extend from wavelengths greater than about 800 nm. In some embodiments, for substantially perpendicular incident light 60 and for the first polarization state, for at least one wavelength greater than about 800 nm, the reflective polarizer 40 may transmit at least about 40% of the incident light 60. In some embodiments, for substantially perpendicular incident light 60 and for the first polarization state, for each wavelength in the infrared wavelength range from about 800 nm to about 1500 nm, the reflective polarizer 40 may have an average transmittance of at least about 40%. In some embodiments, for substantially perpendicular incident light 60 and for an orthogonal second polarization state, the reflective polarizer 40 includes a transmission spectrum 46. Therefore, in some embodiments, the reflective polarizer 40 includes a reflective spectrum 44 corresponding to a first polarization state and a transmission spectrum 46 corresponding to a second polarization state.

[0055] In some embodiments, for substantially perpendicular incident light 60, and for each of the blue peak wavelength 23b, green peak wavelength 23g, and red peak wavelength 23r, the plurality of first polymer layers 41, 42 of the reflective polarizer 40 reflect more than about 60% of the incident light 60 having a first polarization state and transmit more than about 60% of the incident light 60 having an orthogonal second polarization state. In other words, for substantially perpendicular incident light 60, and for each of the blue peak wavelength 23b, green peak wavelength 23g, and red peak wavelength 23r, the reflective polarizer 40 reflects more than about 60% of the incident light 60 having a first polarization state and transmits more than about 60% of the incident light 60 having an orthogonal second polarization state. In some embodiments, for each of the blue light peak wavelength 23b, the green light peak wavelength 23g, and the red light peak wavelength 23r, the plurality of first polymer layers 41, 42 reflect more than about 70% of the incident light 60 having a first polarization state and transmit more than about 70% of the incident light 60 having an orthogonal second polarization state. In some embodiments, for each of the blue light peak wavelength 23b, the green light peak wavelength 23g, and the red light peak wavelength 23r, the plurality of first polymer layers 41, 42 reflect more than about 80%, more than about 90%, more than about 95%, or more than about 99% of the incident light 60 having a first polarization state. In some embodiments, for each of the blue light peak wavelength 23b, the green light peak wavelength 23g, and the red light peak wavelength 23r, the plurality of first polymer layers 41, 42 transmit more than about 80%, more than about 85%, or more than about 90% of the incident light 60 having an orthogonal second polarization state.

[0056] In some embodiments, for substantially perpendicular incident light 60, for a blue light wavelength range extending from about 430 nm to about 480 nm, a green light wavelength range extending from about 500 nm to about 570 nm, and a red light wavelength range extending from about 600 nm to about 680 nm, and for at least one wavelength within each of the blue, green, and red light wavelength ranges, the plurality of first polymer layers 41, 42 reflect more than about 60% of the incident light 60 having a first polarization state and transmit more than about 60% of the incident light 60 having an orthogonal second polarization state. In other words, for substantially perpendicular incident light 60, and for the at least one wavelength within each of the blue, green, and red light wavelength ranges, the reflective polarizer 40 reflects more than about 60% of the incident light 60 having a first polarization state and transmits more than about 60% of the incident light 60 having an orthogonal second polarization state. In some embodiments, for at least one wavelength within each of the blue, green, and red light wavelength ranges, the plurality of first polymer layers 41, 42 reflect more than about 70% of the incident light 60 having a first polarization state and transmit more than about 70% of the incident light 60 having a second polarization state. In some embodiments, for at least one wavelength within each of the blue, green, and red light wavelength ranges, the plurality of first polymer layers 41, 42 reflect more than about 80%, more than about 90%, more than about 95%, or more than about 99% of the incident light 60 having a first polarization state. In some embodiments, for at least one wavelength within each of the blue, green, and red light wavelength ranges, the plurality of first polymer layers 41, 42 transmit more than about 80%, more than about 85%, or more than about 90% of the incident light 60 having an orthogonal second polarization state.

[0057] In some embodiments, for substantially perpendicular incident light 60 and for the blue light peak wavelength 23b, the plurality of first polymer layers 41, 42 reflect more than about 60% of the incident light 60 having a first polarization state and transmit more than about 60% of the incident light 60 having a second polarization state. In other words, for substantially perpendicular incident light 60 and for the blue light peak wavelength 23b, the reflecting polarizer 40 reflects more than about 60% of the incident light 60 having a first polarization state and transmits more than about 60% of the incident light 60 having a second polarization state. In some embodiments, for substantially perpendicular incident light 60 and for the blue light peak wavelength 23b, the plurality of first polymer layers 41, 42 reflect more than about 70%, more than about 80%, more than about 90%, more than about 95%, or more than about 99% of the incident light 60 having a first polarization state. In some embodiments, for substantially perpendicular incident light 60 and for the blue light peak wavelength 23b, the plurality of first polymer layers 41, 42 transmit incident light 60 having a second polarization state greater than about 70%, greater than about 75%, or greater than about 80%.

[0058] refer to Figure 5 and Figure 7 For substantially perpendicular incident light 61, and for each of the first and second polarization states, filter 50 includes a transmission spectrum 54. In some embodiments, the transmission spectrum 54 includes a transmission band 54a. In some embodiments, the transmission band 54a may be located in the wavelength range of about 430 nm to about 750 nm. In some embodiments, for substantially perpendicular incident light 61, and for each of the first and second polarization states, filter 50 transmits more than about 50% of the incident light 61 for each wavelength in the transmission band 54a.

[0059] In some embodiments, for substantially perpendicular incident light 61, for each of the green peak wavelength 23g and the red peak wavelength 23r, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers 51, 52 transmit more than about 70% of the incident light 61. In other words, for substantially perpendicular incident light 61, for each of the green peak wavelength 23g and the red peak wavelength 23r, and for each of the first polarization state and the second polarization state, the filter 50 transmits more than about 70% of the incident light 61. In some embodiments, for substantially perpendicular incident light 61, for each of the green peak wavelength 23g and the red peak wavelength 23r, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers 51, 52 transmit more than about 80% of the incident light 61. In some embodiments, for substantially perpendicular incident light 61, for each of the green peak wavelength 23g and the red peak wavelength 23r, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers 51, 52 transmit more than about 90%, more than about 95%, or more than about 99% of the incident light 61.

[0060] In some embodiments, for substantially perpendicular incident light 61 and a green light wavelength range extending from about 500 nm to about 570 nm, a red light wavelength range extending from about 600 nm to about 680 nm, and for each of the first polarization state and the second polarization state, for at least one wavelength within each of the green light wavelength range and the red light wavelength range, the plurality of second polymer layers 51, 52 transmit more than about 70% of the incident light 61. In other words, for substantially perpendicular incident light 61 and for each of the first polarization state and the second polarization state, for at least one wavelength within each of the green light wavelength range and the red light wavelength range, the filter 50 transmits more than about 70% of the incident light 61. In some embodiments, for substantially perpendicular incident light 61 and for each of the first polarization state and the second polarization state, for at least one wavelength within each of the green light wavelength range and the red light wavelength range, the plurality of second polymer layers 51, 52 transmit more than about 80% of the incident light 61. In some embodiments, for substantially perpendicular incident light 61, and for each of the first polarization state and the second polarization state, for at least one wavelength in each of the green light wavelength range and the red light wavelength range, the plurality of second polymer layers 51, 52 transmit incident light 61 of greater than about 85%, greater than about 90%, greater than about 95%, or greater than about 99%.

[0061] In some embodiments, for substantially perpendicular incident light 61, for the smaller blue light wavelength 25b1, and for each of the first and second polarization states, the plurality of second polymer layers 51, 52 transmit less than about 60% of the incident light 61. In other words, for substantially perpendicular incident light 61, for the smaller blue light wavelength 25b1, and for each of the first and second polarization states, the filter 50 transmits less than about 60% of the incident light 61. In some embodiments, for substantially perpendicular incident light 61, for the smaller blue light wavelength 25b1, and for each of the first and second polarization states, the plurality of second polymer layers 51, 52 transmit less than about 55% or less than about 50% of the incident light 61.

[0062] In some embodiments, for substantially perpendicular incident light 61, and for each of the first polarization state and the second polarization state, the transmittance of the plurality of second polymer layers 51, 52 at the shorter blue light wavelength 25b1 is at least 30% less than the transmittance at the longer blue light wavelength 25b2. In other words, for substantially perpendicular incident light 61, and for each of the first polarization state and the second polarization state, the transmittance of the filter 50 at the shorter blue light wavelength 25b1 is at least 30% less than the transmittance at the longer blue light wavelength 25b2. In some embodiments, for substantially perpendicular incident light 61, and for each of the first polarization state and the second polarization state, the transmittance of the plurality of second polymer layers 51, 52 at the shorter blue light wavelength 25b1 is at least 35%, at least 40%, or at least 50% less than the transmittance at the longer blue light wavelength 25b2.

[0063] refer to Figure 4 , Figure 5 and Figure 7 In some embodiments, for substantially perpendicular incident light 60, for a UV wavelength range extending from about 410 nm to about 420 nm, and for a second polarization state, the plurality of first polymer layers 41, 42 have an average transmittance T1. In some embodiments, for substantially perpendicular incident light 61, for a UV wavelength range extending from about 410 nm to about 420 nm, and for a second polarization state, the plurality of second polymer layers 51, 52 have an average transmittance T2. Therefore, for substantially perpendicular incident light 60, 61, for a UV wavelength range extending from about 410 nm to about 420 nm, and for a second polarization state, the plurality of first polymer layers 41, 42 have an average transmittance T1 and the plurality of second polymer layers 51, 52 have an average transmittance T2, such that T1 / T2 ≥ 1.5. In other words, the ratio of average transmittance T1 to average transmittance T2 is greater than or equal to 1.5. In some embodiments, the average transmittance T2 of filter 50 is less than about 50%.

[0064] In some implementations, T1 / T2 ≥ 1.7. In some implementations, T1 / T2 ≥ 1.9. In some implementations, T1 / T2 ≥ 2.

[0065] In some embodiments, for substantially perpendicular incident light 61, for each wavelength in the UV wavelength range, and for each of the first polarization state and the second polarization state, the filter 50 transmits less than about 60% or less than about 55% of the incident light 61.

[0066] In some embodiments, for substantially perpendicular incident light 61, and for each of the first and second polarization states, the plurality of second polymer layers 51, 52 transmit more than about 30% of the incident light 61 for at least one wavelength within the blue light wavelength range. As described above, the blue light wavelength range extends from about 430 nm to about 480 nm. In some embodiments, for substantially perpendicular incident light 61, and for each of the first and second polarization states, the plurality of second polymer layers 51, 52 transmit more than about 35% of the incident light 61 for at least one wavelength within the blue light wavelength range.

[0067] Figure 8 Transmission spectra 56 and 58, including the corresponding transmission bands 56a and 58a, are shown. (Reference) Figure 4 , Figure 5 and Figure 8 In some embodiments, for substantially perpendicular incident light 61, and for each of the first polarization state and the second polarization state, the filter 50 includes any one of the transmission spectra 54, 56, 58.

[0068] Transmission spectra 54, 56, and 58 can correspond to different configurations of filter 50. Different configurations of filter 50 can be obtained by changing various parameters of filter 50, such as, but not limited to, the average thickness t2 of the second polymer layers 51 and 52 of filter 50, layer count, layer thickness gradient, and material. Filter 50 can be selected based on desired application properties.

[0069] In some implementations, the light comes from an extended lighting source 10 (such as...) Figure 1 The light 20 (shown) includes any of the emission spectra 81, 82, 83, 84, and 85. Emission spectra 81, 82, 83, 84, and 85 can be shown in graph 800 using any suitable energy unit. Blue emission spectrum 21b, green emission spectrum 21g, and red emission spectrum 21r (as shown) Figure 7 (As shown) and emission spectra 81, 82, 83, 84, 85 correspond to different configurations of the extended illumination source 10. Different configurations of the extended illumination source 10 can correspond to different applications.

[0070] Considering the transmission spectra 56, 58, in some embodiments, for substantially perpendicular incident light 61, for each wavelength in the UV wavelength range extending from about 410 nm to about 420 nm, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers 51, 52 transmit less than about 30% of the incident light 61. In some embodiments, for substantially perpendicular incident light 61, for each wavelength in the UV wavelength range, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers 51, 52 transmit less than about 25%, less than about 20%, or less than about 15% of the incident light 61.

[0071] Considering the transmission spectrum 58, in some embodiments, for substantially perpendicular incident light 61, for each wavelength in the blue light wavelength range extending from about 430 nm to about 480 nm, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers 51, 52 transmit less than about 50% of the incident light 61. In some embodiments, for substantially perpendicular incident light 61, for each wavelength in the blue light wavelength range, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers 51, 52 transmit less than about 40%, less than about 30%, or less than about 20% of the incident light 61.

[0072] Considering the transmission spectra 56, 58, in some embodiments, for substantially perpendicular incident light 61, for each wavelength within each of the green and red wavelength ranges, and for each of the first and second polarization states, the plurality of second polymer layers 51, 52 transmit more than about 80% of the incident light 61. As described above, the green wavelength range extends from about 500 nm to about 560 nm. Furthermore, the red wavelength range extends from about 620 nm to about 740 nm. In some embodiments, for substantially perpendicular incident light 61, for each wavelength within each of the green and red wavelength ranges, and for each of the first and second polarization states, the plurality of second polymer layers 51, 52 transmit more than about 80%, more than about 90%, more than about 95%, or more than about 99% of the incident light 61.

[0073] Figure 9 A graph 900 depicts the relationship between the transmission percentage of the optical assembly 600 of the optical system 500 and wavelength. Wavelength is expressed in nanometers (nm) on the horizontal axis. Figure 9 In the diagram, transmittance is expressed as the percentage of transmission on the left vertical axis. Reflectance is expressed as the percentage of reflection on the right vertical axis. The percentage of reflection and the percentage of transmission are complementary, i.e., percentage of reflection = (100 - percentage of transmission).

[0074] refer to Figure 4 , Figure 5and Figure 9 For the optical assembly 600, various optical properties can be represented by substantially perpendicular incident light 60 and / or substantially perpendicular incident light 61. In some embodiments, for substantially perpendicular incident light 60, 61, and for a first polarization state, the optical assembly 600 includes a reflection spectrum 92. In some embodiments, for substantially perpendicular incident light 60, 61, and for a second polarization state, the optical assembly 600 includes a transmission spectrum 94.

[0075] In some embodiments, for substantially perpendicular incident light 60, 61 and for the blue light peak wavelength 23b, the optical assembly 600 reflects more than about 70% of the incident light 60, 61 with a first polarization state and has a transmittance S1 greater than about 30% for an orthogonal second polarization state. In some embodiments, for substantially perpendicular incident light 60, 61 and for the blue light peak wavelength 23b, the optical assembly 600 reflects more than about 80%, more than about 90%, more than about 95%, or more than about 99% of the incident light 60, 61 with a first polarization state. In some embodiments, for substantially perpendicular incident light 60, 61 and for the blue light peak wavelength 23b, the optical assembly 600 transmits more than about 40%, more than about 50%, or more than about 60% of the incident light 60, 61 with a second polarization state. In other words, the transmittance S1 may be greater than about 30%, greater than about 40%, greater than about 50%, or greater than about 60%.

[0076] In some embodiments, for substantially perpendicular incident light 60, 61, and for a lesser blue light wavelength 25b1, the optical assembly 600 reflects more than about 70% of the incident light 60, 61 having a first polarization state, and has a transmittance S2 for a second polarization state such that S2 is at least 10% smaller than S1. In some embodiments, for substantially perpendicular incident light 60, 61, and for a lesser blue light wavelength 25b1, the optical assembly 600 reflects more than about 80%, more than about 90%, more than about 95%, or more than about 99% of the incident light 60, 61 having a first polarization state. In some embodiments, for substantially perpendicular incident light 60, 61, and for a lesser blue light wavelength 25b1, the optical assembly 600 transmits less than about 70%, less than about 60%, less than about 50%, less than about 40%, less than about 30%, or less than about 20% of the incident light 60, 61 having a second polarization state. In other words, the transmittance S2 may be less than about 70%, less than about 60%, less than about 50%, less than about 40%, less than about 30%, or less than about 20%. In some embodiments, the transmittance S2 is at least 15% less than the transmittance S1. In some embodiments, S2 is at least 20%, at least 30%, at least 35%, at least 40%, at least 50%, or at least 60% less than S1.

[0077] refer to Figure 1 , Figure 4 , Figure 5 , Figure 7 and Figure 9 In some embodiments, filter 50 transmits less than about 60% of the incident light 61 for substantially perpendicular incident light 61, for the lesser blue light wavelength 25b1, and for each of the first and second polarization states. In some embodiments, reflective polarizer 40 reflects more than about 60% of the incident light 60 with the first polarization state for substantially perpendicular incident light 60, and for each wavelength in the blue light wavelength range extending from about 430 nm to about 480 nm. Therefore, for the lesser blue light wavelength 25b1, and for each of the first and second polarization states, the optical combination 600 including filter 50 and reflective polarizer 40 can reflect most of the perpendicular incident light. Therefore, for the lesser blue light wavelength 25b1, the optical system 500 including optical combination 600 can have a high overall reflectivity. For the lesser blue light wavelength 25b1, high reflectivity can protect the viewer from the harmful effects of lesser blue light wavelengths (e.g., macular degeneration).

[0078] Filter 50 also has low transmittance relative to reflective polarizer 40 in the UV wavelength range. Therefore, optical assembly 600 has overall low transmittance in the UV wavelength range.

[0079] In some embodiments, for substantially perpendicular incident light 61, for each of the green peak wavelength 22g and the red peak wavelength 22r, and for each of the first polarization state and the second polarization state, the filter 50 transmits more than about 70% of the incident light 61. In some embodiments, for substantially perpendicular incident light 60, and for at least one wavelength within each of the green and red wavelength ranges, the reflecting polarizer 40 transmits more than about 60% of the incident light 60 having an orthogonal second polarization state. Therefore, the optical system 500 can have generally high transmittance over the visible wavelength range, excluding the smaller blue light wavelengths. Therefore, the optical system 500 may not produce undesirable color shifts. Furthermore, the optical system 500 can have high efficiency.

[0080] In some embodiments, for substantially perpendicular incident light 60, 61, and for the blue light peak wavelength 23b, the optical assembly 600 reflects more than about 70% of the incident light 60, 61 having a first polarization state and transmits more than about 30% of the incident light 60, 61 having a second polarization state. In some embodiments, for substantially perpendicular incident light 60, 61, and for the smaller blue light wavelength 25b1, the optical assembly 600 reflects more than about 70% of the incident light 60, 61 having a first polarization state and transmits less than about 60% of the incident light 60, 61 having a second polarization state. Thus, for the second polarization state, the optical assembly 600 can provide a transition from substantially reflecting or blocking the incident light 60, 61 (e.g., transmittance <10% at 420 nm) to substantially transmitting the incident light 60, 61 (e.g., transmittance >50% at 440 nm) within a relatively narrow wavelength range of about 15 nm to about 20 nm. Therefore, for the second polarization state, the optical combination 600 provides a strong transmission band with a sharp band edge required for achieving color-balanced white transmission, while blocking smaller blue light wavelengths. The reflective polarizer 40 and the filter 50 enable the optical system 500 to substantially block low-wavelength blue light in a narrow band. Thus, the combination of the reflective polarizer 40 and the filter 50 of this disclosure exhibits superior performance in reducing the transmittance of smaller blue light wavelengths in the visible spectrum while providing minimal color shift.

[0081] Unless otherwise stated, all figures used in the specification and claims to indicate feature dimensions, quantities, and physical properties should be understood to be modified by the term "about". Therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations and can vary according to the desired properties sought by those skilled in the art using the teachings disclosed herein.

[0082] While specific embodiments have been illustrated and described herein, those skilled in the art will recognize that various alternative and / or equivalent embodiments may be used in place of the illustrated and described embodiments without departing from the scope of this disclosure. This application is intended to cover any modifications or variations of the specific embodiments discussed herein. Therefore, this disclosure is intended to be limited only by the claims and their equivalents.

Claims

1. An optical system, the optical system comprising: An extended illumination source is configured to emit light from its extended emitting surface toward a display panel. The emitted light includes different blue light emission spectra, green light emission spectra, and red light emission spectra. The blue light emission spectra, the green light emission spectra, and the red light emission spectra include corresponding blue light peaks, green light peaks, and red light peaks at corresponding blue light peak wavelengths, green light peak wavelengths, and red light peak wavelengths, as well as corresponding blue light FWHM, green light FWHM, and red light FWHM, wherein the blue light FWHM extends from a shorter blue light wavelength to a longer blue light wavelength. A reflective polarizer is disposed on the emitting surface of the extended illumination source and includes a plurality of first polymer layers totaling at least 10. and A filter, disposed between the reflective polarizer and the emitting surface of the extended illumination source, and comprising at least 10 second polymer layers, each of the first and second polymer layers having an average thickness of less than 300 nm, such that for perpendicularly incident light: For each of the blue light peak wavelength, the green light peak wavelength, and the red light peak wavelength, the plurality of first polymer layers reflect more than 60% of the incident light having a first polarization state and transmit more than 60% of the incident light having an orthogonal second polarization state. For each of the green peak wavelength and the red peak wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit more than 70% of the incident light; and For the smaller blue light wavelength, and for each of the first and second polarization states, the plurality of second polymer layers transmit less than 60% of the incident light.

2. The optical system of claim 1, wherein for the vertically incident light, and for each of the first polarization state and the second polarization state, the transmittance of the plurality of second polymer layers at the shorter blue light wavelength is at least 30% less than the transmittance at the longer blue light wavelength.

3. The optical system of claim 1, wherein for each of the blue light peak wavelength, the green light peak wavelength, and the red light peak wavelength, the plurality of first polymer layers reflect more than 70% of the incident light having the first polarization state and transmit more than 70% of the incident light having the second polarization state, and wherein for each of the green light peak wavelength and the red light peak wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit more than 80% of the incident light.

4. An optical system, the optical system comprising: An extended illumination source is configured to emit light from its extended emitting surface toward a display panel. The emitted light includes different blue light emission spectra, green light emission spectra, and red light emission spectra. The blue light emission spectra, the green light emission spectra, and the red light emission spectra include corresponding blue light peaks, green light peaks, and red light peaks at corresponding blue light peak wavelengths, green light peak wavelengths, and red light peak wavelengths, as well as corresponding blue light FWHM, green light FWHM, and red light FWHM, wherein the blue light FWHM extends from a shorter blue light wavelength to a longer blue light wavelength. A reflective polarizer is disposed on the emitting surface of the extended illumination source and includes a plurality of first polymer layers totaling at least 10. and A filter, disposed between the reflective polarizer and the emitting surface of the extended illumination source, and comprising at least 10 second polymer layers, each of the first and second polymer layers having an average thickness of less than 300 nm, such that for perpendicularly incident light: For each of the blue light peak wavelength, the green light peak wavelength, and the red light peak wavelength, the plurality of first polymer layers reflect more than 60% of the incident light having a first polarization state and transmit more than 60% of the incident light having an orthogonal second polarization state. For each of the green peak wavelength and the red peak wavelength, and for each of the first polarization state and the second polarization state, the plurality of second polymer layers transmit more than 70% of the incident light; and For each of the first polarization state and the second polarization state, the transmittance of the plurality of second polymer layers at the shorter blue light wavelength is at least 30% less than the transmittance at the longer blue light wavelength.

5. The optical system of claim 4, wherein for each of the blue light peak wavelength, the green light peak wavelength, and the red light peak wavelength, the plurality of first polymer layers reflect more than 70% of the incident light having the first polarization state and transmit more than 70% of the incident light having the second polarization state.

6. The optical system of claim 4, wherein for the vertically incident light, for the UV wavelength range extending from 410 nm to 420 nm, and for the second polarization state, the plurality of first polymer layers have an average transmittance T1 and the plurality of second polymer layers have an average transmittance T2, T1 / T2 ≥ 1.

5.

7. The optical system of claim 4, wherein the optical assembly comprises the reflective polarizer and the filter, such that for the perpendicularly incident light: For the blue light peak wavelength, the optical combination reflects more than 70% of the incident light having the first polarization state, and has a transmittance S1 of more than 30% for the second polarization state; and For the smaller blue light wavelength, the optical combination reflects more than 70% of the incident light having the first polarization state, and has a transmittance S2 for the second polarization state, S2 being at least 10% smaller than S1.

8. An optical assembly, the optical assembly comprising: A reflective polarizer comprising at least 10 first polymer layers, each of the first polymer layers having an average thickness of less than 300 nm. and A filter, configured to be in optical communication with the reflective polarizer, includes a plurality of second polymer layers, the total number of which is at least 10 and disposed between opposing outermost polymer layers. Each opposing outermost polymer layer and each second polymer layer between them has an average thickness of less than 300 nm. The thinnest second polymer layer among the plurality of second polymer layers is disposed between and spaced apart from the opposing outermost polymer layers, such that for vertically incident light and in the blue light wavelength range from 430 nm to 480 nm, the green light wavelength range from 500 nm to 570 nm, and the red light wavelength range from 600 nm to 680 nm: For at least one wavelength in each of the blue light wavelength range, the green light wavelength range, and the red light wavelength range, the plurality of first polymer layers reflect more than 60% of the incident light having a first polarization state and transmit more than 60% of the incident light having an orthogonal second polarization state. For each of the first polarization state and the second polarization state, for at least one wavelength within each of the green light wavelength range and the red light wavelength range, the plurality of second polymer layers transmit more than 70% of the incident light; and For the UV wavelength range extending from 410 nm to 420 nm, and for the second polarization state, the plurality of first polymer layers have an average transmittance T1 and the plurality of second polymer layers have an average transmittance T2, T1 / T2 ≥ 1.

5.

9. An optical system, the optical system comprising: An extended illumination source is configured to emit light from its extended emitting surface toward a display panel, the emitted light including a blue light emission spectrum, the blue light emission spectrum including a blue light peak at the blue light peak wavelength and a corresponding blue light FWHM, the blue light FWHM extending from a shorter blue light wavelength to a longer blue light wavelength; and According to claim 8, the optical assembly is disposed on the emitting surface of the extended illumination source such that the filter is disposed between the reflective polarizer and the emitting surface, and wherein for the vertically incident light, and for each of the first polarization state and the second polarization state, the transmittance of the plurality of second polymer layers at the shorter blue light wavelength is at least 30% less than the transmittance at the longer blue light wavelength.

10. The optical system of claim 9, wherein, for the at least one wavelength within each of the blue wavelength range, the green wavelength range, and the red wavelength range, the plurality of first polymer layers reflect greater than 70% of the incident light having the first polarization state and transmit greater than 70% of the incident light having the second polarization state.

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