TWI229744B - Bevel gradient dichroic film and IQC method thereof and liquid crystal on silicon thereof - Google Patents

Abstract

A bevel gradient dichroic film for a liquid crystal on silicon (LCOS) display device is provided. The bevel gradient dichroic film includes a dichroic film having a gradient direction, wherein the gradient direction is dependent on the incident angle of an incident light. The gradient direction of the film property or the film thickness of the film, and the distribution of the film property or the film thickness on the gradient direction can be adjusted. Therefore, a light separated by the film can have uniform distribution of color, energy, reflectivity or transmittance and have a uniform distribution of three primary colors. Accordingly, the brightness, uniformity and contrast resolution of the output image of the LCOS display device can be improved.

Description

1229744 V. Description of the invention (1) Technical field to which the invention belongs The present invention relates to a graded light-splitting film and a reflective liquid crystal projection display device thereof. In particular, the invention relates to an oblique gradient light-splitting film and inspection method and a reflective liquid crystal projection display device which can be applied to an off-axis projector light system and improve its uniformity, brightness, and contrast sharpness. In recent years, liquid crystal displays (Liquid Crystal Display, LCD) have gradually replaced traditional cathode-ray tubes (C ath) because of their advantages such as thin appearance, light weight, low operating voltage, power saving, and no radiation. de Ray Tube, CRT), and become the mainstream of display devices. However, due to the technical limitations of liquid crystal displays (LCD), most of them can only be limited to products with a display screen of less than 30 inches. For displays ranging from 30 inches to 60 inches, the development of Plasma Display Panel (PDP) was originally the most promising. However, because its cost is too high, it cannot become a product acceptable to ordinary consumers. . Therefore, the development direction of large-sized display devices is currently toward the development of display devices using projection technology, such as reflective projection display devices (rearive projection display devices) and rear projection display devices (rear projection display devices). The reflective projection display device includes a liquid crystal projector (Li quid Crystal

(Projector, LCP), digital light source (Digital Light Projector, DLP) and reflective liquid crystal (Liquid Crystal On)

12281twf.ptd Page 8 1229744 V. Description of the invention (2)

Silicon, LCOS) projection display device. In the rear projection display device, a reflective liquid crystal (L C 0 S) projection technology is also used. At present, although the products on the market are mainly liquid crystal projectors (LCP) and digital light source deployment projectors (DLp), because the reflective liquid crystal (LC0S) projection technology has low cost and high aperture ratio (Nanda 9 0 %), High resolution (pixel pitch can be up to 2 mm or less), and many other manufacturers have begun to develop this technology. Therefore, the 'reflective liquid crystal (L C 0 S) projection technology can be said to be the key technology of the reflective projection display device and the rear projection display device. Its biggest advantage is that it can greatly reduce the production cost of the panel and has high resolution. Fig. 1 is a schematic diagram showing a conventional reflection type liquid crystal (LC0s) projection device. Please refer to FIG. 1, in which a reflective liquid crystal (LC 0 S) projection device and its working principle are basically white light 1 〇 4 emitted by a light source 10 2, and red is emitted through a light-transmitting sheet 106 and a dichroic lens 108. Light 112, green light 122 and blue light " 142. Among them, through the dichroic mirror 110, the red light 1 1 2 is reflected by the reflector 1 1 4 to reach the Polarization Beam Splitter (PBS) 116 〇 * Figure 2A and 2B The figure is a schematic diagram illustrating the working principle of a conventional polarization beam splitter (PBS). Here, the incident light is taken as the red light as an example. The depolarized red light 112 passes through the polarization polarization beam splitter (PBS) 1 1 6 in front of the reflective liquid crystal panel (LCOS panel) 118, and the polarization beam splitter (PBS) ) 1 1 6 will only reflect the polarized light in one of the polar directions into the LCOS panel. For example, a polarized eight-mirror (PBS) 1 1 6 is an S polarized light that reflects red light 1 1 2 (S -polarization light) into the reflective liquid crystal panel 118. Please come to Picture 2A ’when the image to be displayed on the reflective liquid crystal panel 1 1 8 is &

1229744

In the state (d a r k), the S polarized light incident on the reflective liquid crystal panel 1 1 8 will be reflected back and cannot enter the X-Cube 1 52. Next, ^ lost reflection 2B picture 'When the desired image is displayed on the reflective liquid crystal panel 1 1 8, the S polarized light entering the LCOS panel 1 1 8 will be redundantly changed to a P polarized light by the LCOS panel. (P-polarization light) 120, so it can pass through the polarization beam splitter 1 1 6 and reach the combined light 1 5 2. 4 Therefore, the red light 112, the green light 122, and the blue light 142, respectively, are reflected by the polarizing beam splitter (PBS) 1 1 6, 1 3 0, and 1 4 4 to the reflective liquid, panel 1 1 8, 1 On 3 2 and 1 4 6, the red, green and blue lights with 3 images are partially polarized via the reflective liquid crystal panel, and then partially polarized red via the combined light prism 1 5 2 The light 1 2 0, the green light 1 3 4 and the blue light 1 4 8 are combined to obtain an image signal. Finally, the image signal is projected on the display screen through the zoom lens 1 5 4. … &Quot; From the above, in the conventional known reflective liquid crystal projection design, the element of splitting and combining light is an important element, because if the ratio of the splitting or combining light is not uniform, it will cause the combined image. Non-uniform and ^ color deviation 'directly affects the uniformity of the image ㈠ "^^" and bright ^ (brightness). In addition, if the three primary colors of light are gathered after the light is combined ^ ^ = true' will cause the combined image Blur directly affects the resolution of the image. At present, in the conventional reflective liquid crystal projection design, the beam splitting element mostly uses X-cube or dichroic or dichroic filter. (Dichroicfi 1 ter). For example, as shown in Figure} X-cube ll0, when the direction of light travel is opposite

1229744 V. Description of the invention (4) It is a light beam. The dichroic mirror 110 shown in FIG. 1 uses a dichroic mirror, a dichroic filter, and a filter. Secondly, in the conventional reflective liquid crystal projection design, the light path (1 i gh t path) of the light travels is mostly parallel to the normal direction of the reflecting surface of the beam splitter. This design is generally called coaxial (〇η-a X is) design. For example, in FIG. 1, the traveling direction of the red light 112 is perpendicular to the reflecting surface 162 of the polarization beam splitter 116 and the reflecting surface 164 of the combining prism 152. Figure 3A is a top view showing the coaxial optical design of a conventional beamsplitter. Fig. 3B is a sectional view showing a schematic diagram obtained from the direction A in Fig. 3A. Fig. 3C is a cross-sectional view showing a light spot obtained on the B-B cross section in Fig. 3A. From Fig. 3B, it can be known that the light 302 is incident on the reflection surface 3 0 6 of the beam splitter 3 0 4 perpendicularly. From Figure 3C, it can be known that the shape of the light spot 312 obtained by the light 3 2 on the reflecting surface 3 0 6 is an ellipse. Generally speaking, this kind of coaxial optical design can get a light spot with good color uniformity 3 1 2. When better color uniformity is needed, optical coating technology can be used to coat the dichroic mirror or dichroic filter with dielectric or metal thin films of different properties to change the transmission of light waves by the interference of light Characteristics. For example, a dichroic mirror or a dichroic filter can be plated with a special optical thin film to form a horizontal gradient coating dichroic mirror or a horizontal gradient coating dichroic. filter) to filter out the more uniform and high-transmittance three primary color lights from the incident light, in order to facilitate the final synthesis of an image with better color uniformity to improve the same

12281twf.ptd Page 11 1229744 V. Description of the invention (5) Color uniformity in axial optical design. FIG. 4 is a schematic diagram showing an off-axis reflective liquid crystal (LCOS) projection device. Please refer to FIG. 4, wherein an off-axis reflective liquid crystal (LC0S) projection device basically works by emitting white light from a light source 40 2 through a dichroic mirror 404 and dividing red light 4 0 6. Green light 4 0 8 and blue light 41 0. The three primary colors of light are polarized by a polarizer (ρ ο 1 arizer) 4 1 2 and incident on the reflective liquid crystal panel 4 1 4. The red light and green light having the image portion are transmitted through the reflective liquid crystal panel 4 1 4 Partially polarized with blue light, and then combined with partially polarized red, green, and blue light via an ana 1 yzer 4 1 6 and dichroicmirror 4 1 8 and Get the image signal, and finally project the image signal onto the display screen. In the off-axis reflection type liquid crystal projection device, there is a problem in that the color distribution of the three primary colors of light after the light separation is uneven. In general, even in an off-axis reflective liquid crystal projection device, a horizontal gradation type dichroic mirror or a horizontal gradation type dichroic filter is used, and the color distribution of the three primary color lights after the light splitting is still not uniform. Therefore, how to improve the uniformity and contrast sharpness of each color distribution of the three primary colors of light in the off-axis reflective liquid crystal projection device is an important issue.

12281twf.ptd Page 12 1229744 V. Description of the invention (6) Another object of the present invention is to propose a reflective liquid crystal projection display device with the oblique gradient light-splitting film of the present invention, so as to effectively enhance the gradient through the oblique gradient. Uniformity, brightness and contrast definition of the splitting beams obtained by the light splitting film. Another object of the present invention is to provide a method for detecting an obliquely graded spectroscopic film, so as to effectively detect the uniformity, brightness, and contrast clarity of a beam of light obtained through the obliquely graded spectroscopic film. In order to achieve one of the objectives of the present invention, the present invention provides an oblique gradient light splitting film, which can be applied to an off-axis reflective liquid crystal projection display device. The light splitting film includes a light splitting film. A gradient direction. The gradient direction of the spectroscopic film is related to an incident angle of an incident light, thereby obtaining a uniform distribution of light characteristics of an incident light on a spot on the spectroscopic film. In one embodiment of the present invention, a material of the above-mentioned obliquely gradient spectroscopic film may include a dielectric or a metal. In one embodiment of the present invention, the obliquely graded spectroscopic thin film described above, which has a graded film property, may include a film thickness or a dielectric property. In one embodiment of the present invention, the above-mentioned oblique gradient light-splitting film has characteristics of the obtained light spot, which may include a uniform energy distribution, a uniform reflectance distribution, or a spectrophotometer for light of different colors. Is uniform. In order to achieve another objective of the present invention, the present invention proposes a reflective liquid crystal projection device, which includes a light source and a dichroic mirror (c ο 1 〇 r

12281twf.ptd Page 13 1229744 V. Description of the invention (7) separation mirror), a polarizer 4 polarizers, a reflective LCD panel, an analyzer and a color recombination mirror . The light source is used to emit white light, and the three primary color lights are separated through a color separation mirror. The three primary colors of light are polarized through a polarizer (ρ ο 1 arizer) and are incident on a reflective liquid crystal panel. The three primary colors of the image portion are polarized through the reflective liquid crystal panel, and then passed through a polarizer ( ana 1 yzer) and a color recombination mirror combine the partially polarized three primary colors of light to obtain an image signal, and finally project the image signal onto a display screen. Among them, at least one of the dichroic mirror or the combiner mirror is formed with the obliquely progressive dichroic film of the present invention. The detailed description of the obliquely progressive dichroic film is described in the above description, and will not be repeated here. In order to achieve another objective of the present invention, the present invention provides a method for detecting an obliquely progressive spectroscopic film. The method includes providing an incident light, which has a plurality of different incident angles for an oblique gradient beam splitting film; and detecting the light characteristics of one of the divided beams obtained by the incident light at different incident angles. Whether it is evenly distributed. In one embodiment of the present invention, as described above, in the method for detecting an obliquely-graded spectroscopic film, the light characteristics of the spectroscopic beam include energy distribution, reflectance, or spectrophotometry for light of different colors. In summary, with the oblique gradient light-splitting film provided by the present invention and its detection method, as well as its reflective liquid crystal projection display device, the direction of the gradation of the thickness or property of the coating layer on the beam splitter and the direction of the incident light Into

12281twf.ptd Page 14 1229744 V. Description of the invention (8) The angle of incidence is related. Therefore, by adjusting the direction of the thickness of the coating layer or the properties of the coating layer on the beam splitter, and the distribution of the thickness of the coating layer or the properties of the coating layer in the direction of change, for example, energy, color, reflectance, or The transmittance, and the spectrophotometry of light of different colors are quite evenly distributed. Therefore, the uniformity of the spectral beams of the reflective liquid crystal projection display device, the uniformity of the beams of different colors, and the available energy of the spectral beams can be greatly improved, that is, the brightness, uniformity, and contrast definition of the output image can be improved. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below in conjunction with the accompanying drawings for detailed description as follows: Embodiment: FIG. 5A is the first View showing the off-axis optical design of the beamsplitter. Fig. 5B is a sectional view showing a schematic diagram obtained from the C direction in Fig. 5A. Figure 5C is a cross-sectional view showing the light spot on the D-D section in Figure 5A. From Fig. 5B, it can be known that the light 502 does not enter the reflecting surface 506 of the beam splitter 504 perpendicularly, but has an angle with the normal of the reflecting surface 506. From Figure 5C, it can be known that the shape of the 1 ight spot 512 obtained by the light 5 2 on the reflecting surface 5 0 6 is an oblique ellipse, and in this off-axis optical design The color uniformity of the light spot 5 1 2 is not good. When better color uniformity is needed, one of the improved methods is to use optical mineral film technology. On the spectroscope 5 0 4

12281twf.ptd Page 15 1229744 V. Description of the invention (9) Dielectric or metal thin film of the same property, in order to change the characteristics of light wave transmission by the interference of light. However, in this off-axis optical design, instead of forming a horizontal gradation beam splitter, but forming a horizontal gradation beam splitter, a bevel gradient coating dichroic mirror is formed. 0 FIG. 6 It is a cross-sectional view showing a schematic diagram of a horizontal progressive beam splitter used in off-axis optical design. Please refer to FIG. 6, wherein the gradation of the key film on the reflecting surface 602 of the spectroscope is, for example, in the direction of the arrow E, the film thickness gradually changes. Basically, for a horizontal progressive beamsplitter, the arrow E is in the horizontal direction. The incident direction of light rays, for example, in FIG. 6, light rays having the same incident angle are represented by straight lines 604. Therefore, it can be known that the incident direction of light is not related to the direction of film thickness change, that is, arrow E. Therefore, in the off-axis optical design, the light is incident obliquely, so the color distribution on the obtained spot is uneven. Fig. 7 is a cross-sectional view showing an obliquely progressive beam splitter for use in an off-axis optical design. Please refer to FIG. 7, in which the thickness direction of the coating layer on the reflecting surface 702 of the spectroscope mirror is gradually changed, or the direction of the property of the coating layer is gradually changed, for example, in the direction of the arrow F, so as to cause the reflecting surface of the spectroscope The thickness or properties of the coated layer are gradually changed. For obliquely progressive beamsplitters, the arrow F is not necessarily in the horizontal direction, but is related to the direction of light incidence. For example, rays with the same incident angle are represented by a straight line 704, so the direction of the arrow F is related to the direction of the straight line 704. By adjusting the thickness or property of the coating layer on the reflecting surface of the beam splitter, for example, the direction of the arrow F and the direction of the arrow F, the thickness or property of the film

12281twf.ptd Page 16 1229744 Fifth, the distribution of the invention (for example), for example, changes in the thickness distribution of the film, you can get a light spot with a fairly uniform color distribution. In an embodiment of the present invention, the straight line 704 may include a curve formed by the same incident angle, and is not necessarily a straight line. In one embodiment of the present invention, a material of the above-mentioned obliquely gradient spectroscopic film may include a dielectric or a metal. In one embodiment of the present invention, the obliquely graded spectroscopic thin film described above, which has a graded film property, may include a film thickness or a dielectric property. In an embodiment of the present invention, the above-mentioned oblique gradient light-splitting film has characteristics of the obtained light spot, which can include a uniform energy distribution, a uniform reflectance distribution, or a spectrophotometry for light of different colors. Is uniform. In the present invention, a reflective liquid crystal (LCOS) projection device is provided. Here, the reflection type liquid crystal projection device of the present invention can take the off-axis reflection type liquid crystal projection device shown in FIG. 4 as an example, but the off-axis reflection type liquid crystal projection device shown in FIG. 4 is only used as an example. Examples are not intended to limit the scope of the invention. Please refer to FIG. 4, where an off-axis reflective liquid crystal (LCOS) projection device includes a light source 402 for emitting white light, and the three primary color lights 406, 408, and 410 are separated through a color separation mirror 404. The three primary colors of light are polarized by a polarizer (ρ ο 1 arizer) 4 1 2 and then incident on the reflective liquid crystal panel 4 1 4. The three primary colors of the image portion are polarized by the reflective liquid crystal panel 4 1 4 After partialization

12281twf.ptd Page 17 1229744 V. Description of the invention (11) (analyzer) 416 and color recombination mirror 4 1 8 Combine the partially polarized three primary colors to obtain the image signal. The video signal is projected on the display. Among them, at least one of the dichroic mirror 404 or the combiner mirror 418 is formed with the oblique gradient beam splitting film of the present invention. The detailed description of the oblique gradient beam splitting film is shown in the above description and FIG. 7. It will not be repeated here. In the present invention, a detection method IQC (incoming quality control) of an obliquely progressive spectroscopic film is provided. The method includes providing an incident light having a plurality of different incident angles for an obliquely gradient beam splitting film; and detecting a light characteristic of one of the obtained divided beams at different incident angles of the incident light. Whether it is evenly distributed. In one embodiment of the present invention, as described above, in the method for detecting an obliquely-graded spectroscopic film, the light characteristics of the spectroscopic beam include energy distribution, reflectance, or spectrophotometry for light of different colors. In summary, with the oblique gradient light-splitting film provided by the present invention and its detection method, as well as its reflective liquid crystal projection display device, the direction of the gradation of the thickness or property of the coating layer on the beam splitter and the direction of the incident light The angle of incidence is related. Therefore, by adjusting the direction of the thickness of the coating layer or the properties of the coating layer on the beam splitter, and the distribution of the thickness of the coating layer or the properties of the coating layer in the direction of change, for example, energy, color, reflectance, or The transmittance, and the spectrophotometry of light of different colors are quite evenly distributed. Therefore, the uniformity of the beam splitting of the reflective liquid crystal projection display device, the uniformity between the beams of different colors, and the available energy of the beam splitting can be improved to a considerable extent, that is, the brightness and uniformity of the output image can be improved.

12281twf.ptd Page 18 1229744 _; _ 5. Description of the invention (12) Uniformity and contrast sharpness. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes and retouch without departing from the spirit and scope of the present invention. The scope of protection of the invention shall be determined by the scope of the attached patent application.

12281twf.ptd Page 19 1229744 Brief description of the drawings Figure 1 is a schematic diagram showing a conventional reflective liquid crystal (LCOS) projection device; Figures 2 A and 2 B are schematic diagrams showing a conventional bias The working principle of a polarizing beam splitter (PBS); Figure 3 A is a top view showing the coaxial optical design of a conventional beam splitter; Figure 3B is a cross-sectional view showing Figure 3A, from the direction A The obtained result is not intended, and FIG. 3C is a sectional view showing a schematic view of a light spot obtained on a BB section in FIG. 3A;

Figure 4 is a schematic diagram showing an off-axis reflective liquid crystal (LC0S) projection device; Figure 5A is a top view showing the off-axis optical design of the beam splitter; Figure 5B is A cross-sectional view showing the intent obtained from the C direction in FIG. 5A. FIG. 5C is a cross-sectional view showing a schematic view of the light spot obtained on the DD section in FIG. 5A. FIG. 6 is A plan view showing a horizontally progressive beam splitter for use in an off-axis optical design; and

Fig. 7 is a cross-sectional view showing an obliquely progressive beam splitter for use in an off-axis optical design. Schematic representations: 1 0 2: light source

12281twf.ptd Page 20 1229744 Brief description of the drawings 1 04: White light 1 0 6: Filter 1 0 8: Dichroic lens 1 1 0: Dichroic mirror 114, 124, 126, 128: Mirror 1 1 2: Red light 1 1 6, 1 3 0, 1 4 4: Polarized beam splitter 1 1 8, 1 3 2, 1 4 6, 2 0 0: Reflective LCD panel 1 2 0: Red light after polarizing 1 2 2: green light 1 3 4: green light after polarizing 1 42: blue light 1 4 8: blue light after polarizing 1 5 2: combined light 1 5 4: zoom lens 1 6 2, 1 6 4: Reflective surface 3 0 2: Light 3 0 4: Beamsplitter 3 0 6: Reflective surface 3 1 2: Light spot 4 0 2: Light source 404: Dichroic mirror 4 0 6: Red light 4 0 8: Green light

12281twf.ptd Page 21 1229744 Brief description of the diagram 410 Blue light 412 Polarizer 414 Reflective LCD panel 416 Polarizer 418 Combined prism 502 Light 504 Beamsplitter 506 Reflective surface 5 12 Light spot 602, 7 0 2: Reflective surface 604 , 7 0 4: straight line E, F: arrow

12281twf.ptd Page 22

Claims (1)

1229744 6. Scope of patent application 1. An oblique gradient light splitting film, which can be applied to an off-axis reflective liquid crystal projection display device, includes: a light splitting film, wherein the properties of a film layer of the light splitting film have a gradation direction; The gradient direction of the spectroscopic film is related to an incident angle of an incident light, thereby obtaining a uniform distribution of light characteristics of an incident light on a spot on the spectroscopic film. 2. The obliquely graded spectroscopic thin film as described in item 1 of the scope of patent application, wherein the film properties include a film thickness. 3. The obliquely graded spectroscopic film as described in item 1 of the scope of patent application, wherein the properties of the film layer include a dielectric property. 4. The obliquely graded spectroscopic film as described in item 1 of the scope of patent application, wherein the film layer includes a dielectric. 5. The obliquely graded spectroscopic film as described in item 1 of the scope of patent application, wherein the film layer comprises a metal film. 6. The obliquely progressive spectroscopic film as described in item 1 of the scope of patent application, wherein the light characteristics of the light spot include an energy distribution. 7. The obliquely progressive spectroscopic film as described in item 1 of the scope of patent application, wherein the light characteristics of the light spot include a reflectance. 8. The obliquely graded spectroscopic film as described in item 1 of the scope of patent application, wherein the light characteristics of the light spot include a spectrophotometer for a light of different colors. 9. The obliquely graded spectroscopic film as described in item 1 of the scope of patent application, wherein the obliquely graded spectroscopic film is different for different incident angles. 12281twf.ptd Page 23 1229744 6. Scope of patent application The incident light can provide uniform distribution of the light characteristics. ίο. A reflective liquid crystal projection display device, comprising: a light source to emit a white light; a color separation mirror to divide the white light into three primary colors; a polarizer (ρ ο 1 arizer) For polarizing the three primary colors; a reflective liquid crystal panel for polarizing the three primary colors of the polarized light according to an input image signal; An analyzer; and a color recombination mirror, wherein the polarizer and the combiner are used to combine the partially polarized three primary colors to obtain an output image signal; Wherein, at least one of the dichroic mirror or the beam combiner is formed with an oblique gradient beam splitting film, and the oblique gradient beam splitting film includes: * a beam splitting film, wherein a property of a layer of the beam splitting film Having a gradation direction; wherein the gradation direction of the light splitting film is related to an incident direction of a light, thereby obtaining a light of the incident light on the film One of the spots has a uniform light distribution. 11. The reflective liquid crystal projection display device as described in item 10 of the scope of patent application, wherein the properties of the film layer include a film thickness. 12. The reflective liquid crystal projection display as described in item 10 of the scope of patent application 12281twf.ptd Page 24 1229744 6. The scope of the patent application shows that the properties of the film layer include a dielectric property. 13. The reflective liquid crystal projection display device described in item 10 of the patent scope, wherein the film layer includes a Dielectric 〇14. The reflective liquid crystal projection display device described in item 10 of the patent application, wherein the film layer includes a metal thin film. 15 · The reflective liquid crystal projection device described in item 10 of the patent application, In the display device, the light characteristic of the light spot includes an energy distribution. 16. The reflective liquid crystal projection display device described in item 10 of the patent scope, wherein the light characteristic of the light spot includes a reflectance. 17 · As in The reflective liquid crystal projection display device j described in item 10 of the patent scope, wherein the light spot of the light spot is particularly It includes one spectrophotometer for light of different colors. 18. The reflective liquid crystal projection display device as described in item 10 of the patent scope, wherein the oblique gradient light-splitting film J is equal to the incident light at different incident angles. A uniform distribution of the light characteristics of the three primary colors of light that can provide the same performance. A method for detecting an oblique gradient beam splitting film includes:-Providing incident light 5 for--oblique gradient beam splitting film having A plurality of different angles of incidence; and detecting whether the light characteristics of one of the split beams obtained by the incident light at different angles of incidence are uniformly distributed. 20. The obliqueness described in item 19 of the patent scope Detecting method of directional progressive beam splitting film, wherein the light characteristic of the splitting beam includes _ an energy Cloth 〇 12281twf.ptd Page 25 1229744 6. Scope of patent application 2 1. The method of detecting an obliquely graded spectroscopic film as described in item 19 of the scope of patent application, wherein the light characteristic of the spectroscopic beam includes a reflectance. 22. The method for detecting an obliquely progressive spectroscopic film as described in item 19 of the scope of the patent application, wherein the light characteristics of the spectroscopic light beam include a spectrophotometer for one of different colors of light. 12281twf.ptd Page 26