PURPOSE: To attain optical transmission, especially, digital optical transmission by providing an outer case having a vent on the surface to cover a main body case thereby decreasing the temperature rise of the main body case and assembling an LD (semiconductor laser) in it.
CONSTITUTION: An outer case 202 is provided to cover the main body case 201. The surface of the outer case 202 has a notch and is bent to have an angle on the surface and a vent 203 is given. The outer case 202 prevents solar rays 20 from being directly incident on the main case 201 and sufficient wind 21 is given to the main body case 201 through the vent 203 of the outer case 202, then the temperature rise of the main body case 201 is prevented. Thus, even when the equipment of the this invention is installed outdoor, the temperature rise of the main body case 201 is small and kept within the operating temperature range (maximum temperature 50°) of the LD 200. In selecting the color of the surface of the outer case 202 as, e.g., white color, the solar ray 20 is reflected more effectively and in selecting the color of the surface of the main body case 201 as, e.g., black color, since the heat dissipation effect is increased and the temperature rise of the main body case 205 is prevented by the increase.
FUJITO KATSUYUKI
ICHIDA TAKESHIGE
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