摘要 |
A plurality of circular figures, each having the same diameter, are formed on a thermal expansile layer, made of a material which is foamed upon heating as a result of absorption of light, in such way that they are spaced at intervals more than 0.3 times as large as a diameter of each circular figure. Upon exposure of the figures to light, each circular figure absorbs light to produce heat. At this time, since the circular figures are formed with appropriate constant intervals between them, the circular figures are raised so as to have uniform size and shape without being affected by the light absorption and heat generation of other circular figures.
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