TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Components: The reinforcing material includes one of glass fiber, glass fabric, glass nonwoven fabric, and glass fiber mesh.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The halogen-containing polyimide is formed from a polyamic acid copolymer polymerized to halogen group 2 organic functional anhydride and halogen or non-halogen group 2 or 3 organic functional amine compound, or polyamic acid copolymer polymerized to non-halogen group 2 organic functional anhydride and halogen or non-halogen group 2 or 3 organic functional amine compound. The halogen group 2 organic functional anhydride is of formula (I). The non-halogen group 2 organic functional anhydride is of formula (II) or (III). The non-halogen group 2 organic functional anhydride comprises 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydrobenzo(e)isobenzofuran-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-7-methyl-3a,4,5,7a-tetrahydroisobenzofuran-1,3-dione, 4-(2-(2,6-dioxomorpholin-4-yl)ethyl)morpholine-2,6-dione, furo(3,4-f)isobenzofuran-1,3,5,7-tetrone, 5-(1,3-dioxoisobenzofuran-5-yl)isobenzofuran-1,3-dione, 5-(1,3-dioxoisobenzofuran-5-yl)oxyisobenzofuran-1,3-dione, 5-(1,3-dioxoisobenzofuran-5-carbonyl)isobenzofuran-1,3-dione, 5-(1,3-dioxoisobenzofuran-5-yl)sulfonylisobenzofuran-1,3-dione, 5-((4-(1-(4-(1,3-dioxoisobenzofuran-5-yl)oxyphenyl)-1-methyl-ethyl)phenyl)methyl)isobenzofuran-1,3-dione, 3a,4,4a,7a,8,8a-hexahydrofuro(3,4-f)isobenzofuran-1,3,5,7-tetrone, and tetrahydrofuran-2,5-dione compounds of formula (IV) and (V). The halogen or non-halogen group 2 or 3 organic functional amine compound comprises linear or branched 1-30C alkylendiamine, 5-30C cycloalkenylene diamine, 6-30C arylene amine, or 7-30C arylalkylene amine, and further includes halogen, oxygen, sulfur, and silicone. A difference between a refractive index of the matrix and a refractive index of the reinforcing material is less than or equal to 0.01. An amount of the reinforcing material is 40-95 wt.%. An amount of the matrix is 5-60 wt.%. The composite sheet has a light transmittance of 85% at a wavelength of 550 nm. A thermal decomposition temperature of the matrix is greater than or equal to 400 degrees C.A = linear or branched 1-20C halo alkylene;R1-R4 = 1-10C alkyl;a-d = 0-3;Z = single bond, -(C=O)-, -O-, -S- or -SO2-; andZ1, Z2 = 0-5C alkylene.