Lens cap for optical module

#1. Field of the Invention

#The present invention relates to a lens cap for an optical module, and particularly to a lens cap for an optical module such as a transceiver, an optical sub assembly, or a semiconductor laser device.

#2. Related Art

#FIG. 1 is a partly cross-sectional view of a conventional laser device;

#FIG. 2 is a perspective view of a lens cap for an optical module according to the present invention, without an optical lens;

#FIG. 3 is a perspective view of the lens cap of FIG. 2, with the optical lens;

#Referring to FIGS. 2-5, a lens cap 20 for an optical module in accordance with a preferred embodiment of the present invention includes a housing 21 and an optical lens 22. The housing may be of a metallic material, or may be made of another suitable material.

#The housing 21 includes a cylindrical sidewall 23 and a top wall 24 connecting with the sidewall 23. An annular flange 25 extends outward from a bottom of the sidewall 23, and an annular boss 26 protrudes downwardly from the flange 25. The flange 25 and the boss 26 help seal the lens cap to a base (not shown) on which optical elements (not shown), such as a laser diode and an optical detector, are mounted. The top wall 24 includes an inclined portion 241 and a horizontal portion 242 connecting with the inclined portion 241. A through-hole 243 is defined in the inclined portion 241 and includes a window 244 for transmitting a beam of light therethrough and an injection void 245 connecting with the window 244. The drawings show the injection void 245 penetrating all the way through the inclined portion 241, but it may also be a recess in the inclined portion 241. A holding portion 246 is formed on an edge of the through-hole 243, protruding into the through-hole 243.

#The optical lens 22 is insert-molded into the through-hole 243. The optical lens 22 is made of an optical plastic which transmits and reflects light. The housing 21 is placed in a mold (not shown) and melted optical plastic is injected into the mold at the injection void 245 of the housing 21. The melted optical plastic fills the injection void 245 and flows from the injection void 245 into the window 244, filling the window 244. After the optical plastic has been cooled and cured, the mold is opened and the housing 21 with newly formed optical lens 22 is extracted. The shape of the optical lens 22 matches that of the through-hole 243 and is secured in the through-hole 243 by the holding portion 246. The optical lens 22 is designed so that when a beam of light is emitted from the optical elements, one portion of the light is transmitted through the optical lens 22, and the other portion is reflected by the optical lens 22.