| 摘要 |
PROBLEM TO BE SOLVED: To make thin an optical device by preventing a defect due toαrays in an image pick-up element, and at the same time fitting the image pick-up element to cover glass by a bump. SOLUTION: A device 1 comprises an image pick-up element 12, cover glass 13, a signal-processing part 14 or the like such as an electrical circuit for driving the image pick-up element 12 and an electrical circuit for converting the output of the image pick-up element 12 or processing it. In this case, the cover glass 13 is provided so that it covers the image pick-up element 12 and is formed by optical glass with a linear surface densityαof 0.01 count/(cm<2> .h) or less, namely optical glass whose uranium and thorium being contained in the cover glass is 30 ppb or less and 30 ppb or less, respectively.
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