Collimator block for optical functional module

An optical functional module collimator block capable of easily adjusting the position and/or direction of collimators opposed to each other and capable of correcting an error in the position or direction. The collimator module has an adjusting device for optical axis alignment between two collimators held by holding members on a base member in a state of being opposed to each other. The adjusting device includes fixing screws for fixing at least one of the holding members on the base member, and adjusting screws for adjusting the position and/or direction of the holding member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical functional module collimator block in accordance with the present invention will be described with reference to the accompanying drawings. The following description of embodiments of the present invention is made only for the purpose of illustration and is not be construed as a limitation to the scope of the invention. Various modifications of the embodiments of the invention including some or all of the components are conceivable by those skilled in the art. Such modifications also fall within the scope of the invention. (First Embodiment) An optical functional module collimator block 100 which represents a first embodiment of the present invention will be described with reference to FIGS. 1 and 2 . The optical functional module collimator block 100 is constituted by holding members 103 and 103 ′ disposed on a base member 104 to respectively hold collimators 101 and 101 ′, an optical cable 102 connected to the collimator 101 , an optical cable 102 ′ connected to the collimator 101 ′, and adjustment member 120 for fixing the holding member 103 on the base member 104 . The adjustment member 120 is constituted by fixing screws 107 , adjusting screws 108 for adjustment of the position and direction of the holding member 103 , and an optical functional component mount 105 on which an optical functional component (not shown) such as an attenuator, a shutter device or a switching device is placed. The optical functional component mount 105 is formed as a recess in the metallic base member 104 and includes threaded holes 113 and guide pins 114 for fixing the optical functional component. Preferably, stainless steel, e.g., one selected from SUS 304 , 312 , 316 , and so on is used as the material of the holding members 103 and 103 ′, the base member 104 , the fixing screws 107 and the adjusting screws 108 to prevent formation of rust during a long period. A super engineering plastic may be used as the material of the holding members 103 and 103 ′, the base member 104 , the fixing screws 107 and the adjusting screws 108 in order to limit the amount of thermal expansion. Super engineering plastics have a thermal expansion coefficient of smaller than that of conventional engineering plastics and the extent of expansion of super engineering plastics caused by heat is small. The thermal expansion coefficient of polyetheretherketone (PEEK), which is one of typical super engineering plastics, is 2.3×10 −5 /K at 200° C., smaller than 2.7×10 −5 /K of polycarbonate (PC), which is one of the conventional engineering plastics. An optical signal supplied through the optical capable 102 is transmitted as a bundle of parallel rays from the collimator 101 to the collimator 101 ′ opposed to the collimator 101 . A beam 106 is thereby formed in the space between the opposed collimators 101 and 101 ′. An optical functional component (not shown) is placed on the optical functional component mount 105 so as to contain the path for the beam 106 . The optical functional component is thereby enabled to perform its function. The arrangement may be such that three or more collimators are provided on the base member 104 , two or more collimators are disposed at positions opposite from one collimator, and a switching device using refraction of light is used as an optical functional component, thereby enabling switching between optical signal paths. Further, a plurality of collimators may be disposed at positions such as to be opposed to another plurality of collimators. For example, three collimators are disposed at positions such as to be opposed to two collimators. The holding member 103 on which the collimator 101 is mounted is mounted on the base member 104 with the fixing screws 107 as an adjustment portion, as shown in FIGS. 1B and 1C . Each fixing screw 107 has a fine strong thread. The base member 104 has corresponding through holes formed therethrough between its front and back surfaces. The holding member 103 has threaded holes corresponding to the fixing screws 107 . Joining of the holding member with the screws 107 includes a “temporary fixing” function, whereby the efficiency and facility with which mounting and adjusting operations are performed after joining of the holding member are improved. The adjusting screws 108 also have a fine strong thread similar to that of the screws 107 . The base member 104 has corresponding female threads formed therethrough between its front and back surfaces. When one of the adjusting screws 108 is turned for screwing into the female thread, it acts as a “push screw” by exerting an upward force from the base member 104 to push upward the holding member. Therefore each screw 107 acts as a “pull screw” to pull back the holding member 103 toward the base member 104 by a force produced as reaction to the force of the adjusting screws 108 . By the interaction of the forces of the fixing screws 107 and the adjusting screws 108 in different directions, the holding member 103 and the base member 104 can be fastened to each other more firmly. A backlash prevention effect can also be obtained by using the interaction, thereby enabling prevention of loosening of the fixing screws 107 and the adjusting screws 108 and maintenance of the fastened state over a long time period. The fixing screws 107 and the adjusting screws 108 having the function of fixing the holding member 103 on the base member 1 also function as adjustment member in such a manner that when an error in position or direction of the collimator 101 or 101 ′ results in optical axis misalignment between the collimators 101 and 101 ′, which are opposed to each other, the fixing screws 107 and the adjusting screws 108 are operated to align the optical axes of the collimators 101 and 101 ′ by adjusting the position and the direction of the holding member 103 on which the collimator 101 is mounted, and to maintain the adjusted position and direction. FIGS. 2A and 2B are diagrams showing the method of adjusting the position of the holding member 103 . When there is a need to move the collimator 101 upward, all the fixing screws 107 and the adjusting screws 108 are turned for screwing into the threaded holes through the same distance, thereby shifting the collimator 101 upward. FIGS. 2C and 2D are diagrams showing the method of adjusting the direction of the holding member 103 . When there is a need to make the collimator 101 face upward, the adjusting screws 108 A are turned for screwing into the threaded holes, the adjusting screws 108 B are turned for unscrewing, and the fixing screws 107 are adjusted in relation to the operations of the adjusting screws, thereby making the collimator 101 face upward. Through the interaction of the forces of the fixing screws 107 and the adjusting screws 108 in different directions, the adjusted position of the holding member 103 can be maintained with improved reliability over a long time period. (Second Embodiment) FIGS. 3 A, and 3 B are a plan view and a front view, respectively, of an optical functional module collimator block 100 which represents a second embodiment of the present invention, and FIG. 3C is a sectional side view taken along the line B-B′ in FIG. 3A . The optical functional module collimator block 100 of the second embodiment of the present invention is characterized by a modification made in the first embodiment. The modification comprises forming a channel 109 in the base member 104 and replacing the holding member 103 in the first embodiment ( FIGS. 1A, 1B , and 1 C) with a holding member 110 having an insertion portion fitted to the channel 109 . The channel 109 and the insertion portion of the holding member 110 are adjusted in advance to have such an amount of play therebetween that direction adjustment can be performed when the insertion portion is inserted in the channel 109 . The holding member 110 is inserted into the channel 109 to be stabilized. The holding member 110 is thereby prevented from falling at the time of each of mounting, position adjustment, and direction adjustment with the fixing screws 107 and the adjusting screws 108 , thus improving the efficiency and facility with which the mounting or adjusting operations are performed. The shapes, functions, effects, etc., of the other members are the same as those in the optical functional module collimator block 100 of the first embodiment. (Third Embodiment) FIG. 4A is a plan view of an optical functional module collimator block 100 which represents a third embodiment of the present invention, and FIG. 4B is a sectional side view taken along the line C-C′ in FIG. 4A . The optical functional module collimator block 100 of the third embodiment of the present invention has pressing members 112 provided as an adjustment member instead of the fixing screws 107 and the adjusting screws 108 in the first and second embodiments of the present invention. In this embodiment, the base member 104 has a wall portion 111 projecting upwardly. A holding member 115 to which the pressing members 112 and the collimator 101 are attached is inserted in the wall portion 111 and supported on the same by means of the pressing members 112 . The holding member 115 is smaller in size than each of the holding member 103 ( FIGS. 1A, 1B , and 1 C) of the first embodiment and the holding member 110 ( FIGS. 3A, 3B , and 3 C) of the second embodiment. The length of the screw in each pressing member 112 can be changed to enable fine adjustment of the force of pressing the holding member 115 . Therefore it is possible to move the holding member 115 in all directions by adjusting the pressing forces of the pressing members 112 , thus achieving the desired optical axis alignment effect. The shapes, functions, effects, etc., of the other members are the same as those in the optical functional module collimator block 100 of the first or second embodiment. While in each of the optical functional module collimator block 100 of the first and second embodiments the fixing screws 107 and the adjusting screws 108 stand upright on the block, the arrangement may alternatively be such that a wall portion is provided on the base member 104 at such a position so as to face the side surface of the holding member 103 shown in FIGS. 1A to 1 C or the holding member 110 shown in FIGS. 3A to 3 C, and the fixing screws 107 and the adjusting screws 108 are disposed so as to project horizontally from the wall portion to the side surface of the holding member 103 of 110 . This arrangement (not shown) enables finer position and direction adjustment. In each of the optical functional module collimator block 100 of the first and second embodiments, only one 103 or 110 of the holding members holding the two collimators can be adjusted in position and direction, while the opposed holding member 103 ′ is fixed as a wall portion on the base member and cannot be moved for adjustment. However, the present invention is not limited to this arrangement. Other adjustment member (not shown) may be provided to enable adjustment of the position and direction of all the plurality of collimators. In the third embodiment shown in FIGS. 4A and 4B , one pressing member 112 is provided on each of the top, bottom, and two side surfaces of the holding member 115 . However, this construction is not exclusively used. Two pressing members may be provided on each surface to enable direction adjustment based on the same principle as that of the method shown in FIGS. 2A to 2 D. The optical functional module collimator block 100 shown in FIGS. 4A and 4B exemplifies the case where only one of the two collimators opposed to each other is adjustable. However, the present invention is not limited to this. Other holding and pressing members 115 and 112 may be provided to enable adjustment of the position and direction of all the plurality of collimators. According to the present invention, as described above, an optical functional module collimator block can be provided in which the position and direction of at least one of collimators opposed to each other can easily be adjusted to correct the misalignment between the optical axes of the collimators, the adjusted position and direction can be maintained with reliability over a long time period, and further adjustment can be performed if necessary.