System and method for visual quality characterization of holographic materials
View Patent ↗Apparatus and method for characterizing perceived visual quality of holographic materials, such as diffraction gratings. A white light source directs a collimated beam onto an embossed material. The first order diffracted light strikes a white background directly in view of a digital camera, which records an image. The image is analyzed to calculate total color intensity of the diffracted light and an estimate of the color distinctness. The data is compared to other samples to determine relative visual quality.
1. A method for characterizing the perceived visual quality of a holographic material, which, when illuminated, produces diffracted light and scattered light, the method comprising:
directing light from a collimated white light source onto the holographic material;
performing a measurement of the diffracted light;
performing a measurement of the scattered light; and
comparing said measurement of diffracted light and measurement of scattered light to measurements for like holographic materials.
2. The method of claim 1 , wherein said measurement of diffracted light is a measurement of first order diffracted light.
3. The method of claim 1 , further comprising the steps of
directing a portion of the diffracted and the scattered light onto a surface;
creating an image of said surface with a CCD array; said image representing light intensity, and measuring a portion of said image to perform said measurements of the diffracted light and the scattered light.
4. The method of claim 3 , wherein said image comprises red, green and blue images and said measurements are performed separately for each of said red, green and blue images.
5. The method of claim 3 wherein said image of said surface is broken into a plurality of elements and each element is measured to perform said measurements of the diffracted light and the scattered light.
6. The method of claim 5 , wherein said plurality of elements is comprised of sections of annular elements.
7. The method of claim 5 , wherein said plurality of elements is comprised of rectangular elements.
8. A method for characterizing the perceived visual quality of a holographic material, which, when illuminated, produces diffracted light and scattered light, the method comprising:
directing light from a collimated white light source onto the holographic material;
projecting the diffracted and the scattered light onto a scattering surface;
creating an image of the diffracted and scattered light projected onto a scattering surface;
measuring said image to produce a measurement of the diffracted light and a measurement of the scattered light; and
comparing said measurement of diffracted light and measurement of scattered light to measurements for like holographic materials.
9. The method of claim 8 , wherein said image is created with a CCD.
10. The method of claim 8 , wherein said image is created of red, green and blue components of said light projected onto a scattering surface.
11. An apparatus for characterizing the perceived visual quality of a holographic material which, when illuminated, produces diffracted light and scattered light, comprising:
a white light source to produce a collimated light beam;
a scattering surface; and
a light measurement device,
wherein said collimated white light beam is directed to the holographic material, the diffracted light and the scattered light are projected onto said scattering surface and said light projected onto said scattering surface is measured with said light measurement device.
12. The apparatus of claim 11 , wherein said light measurement device is a CCD.
13. The apparatus of claim 12 , wherein said CCD creates an image of said light projected onto said scattering surface, said image comprised of a plurality of pixels, said pixels consisting of pixels representing red, green and blue components of said projected light and said measurement of light projected is performed separately for said red, green and blue components.