Abstract: An apparatus for testing an edge portion of a substrate, includes a first illumination source configured to irradiate light to an end portion of the edge portion of the substrate; a second illumination source configured to irradiate light to a lower portion of the edge portion; a third illumination source configured to irradiate light to an upper portion of the edge portion; and first to third photographing portions, respectively corresponding to the first to third illumination sources, wherein the first illumination source comprises a C-shaped cross-section and comprises a first curved surface facing the end portion of the edge portion, the second illumination source comprises a half C-shaped cross-section and comprises a second curved surface facing the lower portion of the edge portion, and the third illumination source comprises a half C-shaped cross-section and comprises a third curved surface facing the upper portion of the edge portion.

Abstract: An apparatus for testing an edge portion of a substrate, includes a first illumination source configured to irradiate light to an end portion of the edge portion of the substrate; a second illumination source configured to irradiate light to a lower portion of the edge portion; a third illumination source configured to irradiate light to an upper portion of the edge portion; and first to third photographing portions, respectively corresponding to the first to third illumination sources, wherein the first illumination source comprises a C-shaped cross-section and comprises a first curved surface facing the end portion of the edge portion, the second illumination source comprises a half C-shaped cross-section and comprises a second curved surface facing the lower portion of the edge portion, and the third illumination source comprises a half C-shaped cross-section and comprises a third curved surface facing the upper portion of the edge portion.

Abstract: A rewritable, color image recording medium composed of a pair of opposed substrates at least one of which is transparent, and an intermediate layer interposed between the substrates. The intermediate layer contains at least one cholesteric liquid crystal compound having a molecular weight of not greater than 2,000 and a glass transition point of at least 35.degree. C., and a photochromic compound. By irradiating the intermediate layer imagewise with the light through the transparent substrate, while maintaining the intermediate layer at such a temperature that the cholesteric liquid crystal compound assumes a cholesteric liquid crystal phase, an image is formed. The image may be fixed by rapidly cooling the recording medium to a temperature lower than the glass transition.