| 摘要 |
PURPOSE:To avoid an attachment of dust or vapor, by masking the front part of the detecting window of an optical detecting device with an air layer having no break. CONSTITUTION:The entire front circumference of the front glass 2 of the TV camera case 1 that serves as an optical detecting device is covered with hood 3. A ring-shaped pipe 7 is provided in front of the hood 3, and a slit type hole 9 is drilled over the entire circumference inside the pipe 7. At the same time, a high-pressure air inlet 6 is provided to the pipe 7 to introduce the high-pressure air. As a result, a conical air curtain is formed to produce no front gap to the hood 3. Thus the dust or vapor can be prevented from intruding into and settling on the inside of the case 1. |
