Nanomover for optical elements alignment without driving electrically

A mechanical nanomover for optical elements alignment comprises a platform; a front supporting block and a rear supporting block; a left metal sheet and a right metal sheet installed between the two supporting blocks; a movable block installed between the two metal sheets; a weak spring and a strong spring which are interacted with the movable block. A translation stage serves to drive the weak spring to drive the movable block. The elastic coefficient of the strong spring is much greater than that of the weak spring so that the larger displacement of the weak spring will induce only a small displacement of the movable block due to the interaction of the strong spring. No electric power is needed to drive the structure of the nanomover. The mechanical nanometer can provide a sufficient precision to the operation, while it is very inexpensive.

FIELD OF THE INVENTION

The present invention relates to alignment of optical elements; and particularly to a mechanical nanomover for optical elements alignment; in that no electric power is needed to drive the nanomover of the present invention. The moving extent of a weak spring is so large so that the user's hand is sufficient to control a movable block to move only a small sub-micrometer displacement so that the mechanical nanomover of the present invention can provide a sufficient precision to the operation, while it is very cost effective.

BACKGROUND OF THE INVENTION

A nanomover is a device serving to move an object through a very small range, such as several sub-micrometers, or several nanometers, which is especially used in the alignment of optical elements.

With the growth in the optical communication and many other optical applications, optical elements alignment has become the focus of much industrial attention. This is a key production process because the connection efficiency of the optical elements greatly influences the overall production rates and the quality of the connected optical elements for the products used in optical communication.

For example, optical fiber alignment is necessary when two optical fibers are connected, when an optical fiber is connected to a photo diode or a light emission diode and when an optical fiber array is connected to an optical wave guide.

Metallic wire connection is relatively easy because an electric current will flow as long as the two wires are in contact. The connection between two optical elements, such as optical fibers, however, requires much greater precision, in the order of sub-micro-meters. Therefore, experienced technicians are needed for optical elements alignment, but as such technicians are limited in supply, this causes a bottleneck to the mass production of components for optical communications.

Automatic alignment system can shift slightly the light axes of two optical elements, such as optical fibers to minimize transmission loss. Once alignment is complete, the light axes are fixed by laser processing or a setting resin.FIG. 10shows the organization of the typical alignment system. The system consists of a light source, alignment stages, a stage controller, a power meter to measure the light intensity, and a controlling PC. The alignment stage moves the tip of one optical fiber with sub-micrometer precision using step motors. The PC controller receives information from the power meter and feedbacks the information to the stage controller to control the alignment stage. The control signals are generated by the PC where the alignment is executed.

In above structure, the step motor can be replaced by a piezoelectric element which can convert electric energy into mechanic action so as to drive the clamp arm with a V groove locating an optical fiber.

Above mentioned structures are driven electrically and can achieve a desired precision for moving the clamp arm with a minor distance in sub-micrometer ranges. However this device is very expensive and must be driven electrically. Thus, there is an eager demand for a novel design which can improve the above mentioned disadvantages.

SUMMARY OF THE INVENTION

Accordingly, the primary object of the present invention is to provide a mechanical nanomover for optical elements alignment; in this device, no electric power is needed to drive the structure of the nanomover. The moving extent of a weak spring is so large so that the user's hand is sufficient to control a movable block to only move through a small displacement. Thus the mechanical nanomover can provide a sufficient precision to the operation, while it is very cost effective.

To achieve above objects, the present invention provides a mechanical nanomover for optical elements alignment which comprises a platform; a front supporting block and a rear supporting block placed upon the platform; a left metal sheet and a right metal sheet installed between the two supporting blocks; a movable block installed between the two metal sheets; a weak spring and a strong spring which are interacted with the movable block. A translation stage serves to drive the weak spring to drive the movable block. Other than the front supporting block and the rear supporting block, all the elements are located not to contact the platform so as to provide a frictionless system in operation. The elastic coefficient of the strong spring is much greater than that of the weak spring so that the larger displacement of the weak spring will induce only a small displacement of the movable block due to the interaction of the strong spring. The mechanical nanomover can provide a sufficient precision to the operation, while it is very cheap.

In the present invention, the weak spring601is an elastic reed and the strong spring602is another elastic reed. Furthermore, the driving unit700is a translation stage which has an axle; one end of the axle is connected to the weak spring and another end of the axle is threaded to a casing of the translation stage. The front supporting block201and the rear supporting block202are rigid bodies.

Moreover, in the present invention, a preload is added to the moveable block. In an assembly state, the strong spring is compressed with a very little extent so as to apply a predetermined preload to the moveable block and thus the right metal sheet301and left metal sheet302will also deform with the same extent experienced by the moveable block400.

DETAILED DESCRIPTION OF THE INVENTION

With referring toFIGS. 1,2,3,4,5and6, whereFIG. 1is an exploded perspective view showing the elements of the present invention in the first embodiment of the present invention.FIG. 2shows an assembly view of the present invention.FIG. 3is a partial perspective view of view of the present invention.FIG. 3is a partial perspective view of the present invention in the first embodiment of the present invention, where the elements202and302are removed for showing the interior of the structure of the present invention.FIG. 4is another partial perspective view of the present invention in the first embodiment of the present invention, where the elements201and301are removed for showing the interior of the structure of the present invention.FIG. 5shows a cross sectional view about the assembled state of the present invention.FIG. 6shows another cross sectional view about the assembled state of the present invention, which is viewed from a side vertical to the side shown inFIG. 5. The elements of the present invention will be described in the following.

A platform100has an upper surface101and a lower surface102. Preferably, the upper surface101is a flat surface.

A front supporting block201and a rear supporting block202are firmly installed upon the upper surface101of the platform100. For example, the front supporting block201and the rear supporting block202can be embedded into, or screwed to or locked to the upper surface101of the platform100. In the drawing, the screw connection is illustrated. The front supporting block201and the rear supporting block202are retained with a distance for receiving other elements of the present invention. In the present invention, the front supporting block201and the rear supporting block202are rigid bodies and thus are difficult to deform in the operation of the device of the present invention.

A right metal sheet301and a left metal sheet302are arranged between and firmly secured to the front supporting block201and the rear supporting block202. The right metal sheet301is spaced from the left metal sheet302. The right metal sheet301and the left metal sheet302are suspended between the front supporting block201and rear supporting block202and are not contact with any surface of the platform100. The right metal sheet301and left metal sheet302are made of flexible material. That is to say, the right metal sheet301and left metal sheet302are slightly elastic and thus deformable within a slight extent.

A movable block400is arranged between the right metal sheet301and left metal sheet302and is firmly secured thereto. A lower surface401of the movable block400is spaced from the upper surface101of the platform100. In the present invention, for example the movable block400is screwed to the right metal sheet301and left metal sheet302so that the movable block400, right metal sheet301and left metal sheet302are formed as a rigid structure, that is, no relative movement between the movable block400and the left metal sheet302and between the movable block400and the right metal sheet301. As the movable block400moves, the left metal sheet302and right metal sheet301are also moved with the same extent. No relative movement exists therebetween.

In operation, the optical element for alignment can be placed upon the moveable block400, for example, if the optical element is an optical fiber, than a clamp arm is located upon an upper surface402of the moveable block400. The clamp arm has a V shape groove for locating an optical fiber. In alignment of two optical fibers, it is necessary to fine-adjust the moveable block400so as to drive the clamp arm to align with another one. However the core of a fiber is very tiny, generally, it has a size of micrometers. Thus the movement of the optical fiber is just a few micrometers. Therefore, it is needed to have a design which cause the moveable block400to move several micrometers in many steps with each step in the range of several sub-micrometers, while these minor steps must be controllable by the operation. The following elements of the present invention cause this idea could be realized, while electric power is unnecessary.

A first rod501is connected to the lower surface401of the movable block400, while do not contact the upper surface101of the platform100.

A weak spring601has a middle section connected to the first rod501. The weak spring601has a small elastic coefficient K1.

A strong spring602has two ends which are firmly secured (or exampled screwed) to the front supporting block201and rear supporting block202. The middle section of the strong spring602is contact to the right metal sheet. The strong spring602has a large elastic coefficient K2. The large elastic coefficient K2is much greater than the small elastic coefficient K1. For example the large elastic coefficient K2is 50 times or 100 times of the small elastic coefficient K1.

In the present invention, it is preferable, that the weak spring601and the strong spring602are elastic reeds which could provide a steady operation which is a main concern in the present invention. Generally, elastic reeds are preferred than helical springs. However all elastic springs are suitably used in the present invention after they are especially selected and designed, and thus all these are within the scope of the present invention.

A translation stage700is connected to the weak spring601. Adjustment of the translation stage700will release or tighten the weak spring601. However the main design of the translation stage700is to tighten (and thus compress) the weak spring601or extend (and thus prolong) the weak spring601, that is to adjust the length of the weak spring601.

Thus, other structure suitable for above mentioned function is permissible to be used in the present invention. As illustrated in the drawing, we depict that the translation stage700is protruded out from a lower side of the right metal sheet301, but this is not confined to confine the scope of the present invention. Other design suiting for the operation of the translation stage700is permissible in the present invention.

In the present invention, other driving apparatus which can compress or expand the weak spring601is also within the scope of the present invention.

In the present invention, the translation stage700serves to convert screwing operation into linear operation. In the drawing, it is illustrated that the translation stage700has a screwing head701for driving the plate702to move along a base703. The retaining block704is locked to the plate702. Two ends of the weak spring601are locked to the retaining block704. In operation, screwing the head701will cause that weak spring601to move forwards or backwards.

Operation of the present invention will be described herein. Initially, the structure of the present invention is at a wholly released state. That is to say, the weak spring601is completely released without compression or extension. Then the translation stage700is screwed forwards to push the weak spring601forwards. The movement of the weak spring601will drive the first rod501also moves forwards. As a result, the movable block400will move leftwards to drive the left metal sheet302and right metal sheet301to also move leftwards. However the movement of the moveable block400is interacted with the strong spring602through the right metal sheet301, while the strong spring602has a large elastic coefficient K2which is far greater than that of weak spring601. For example, herein we assume that the large elastic coefficient K2is 100 times of the small elastic coefficient K1. Thus the strong spring602will strongly retain the moveable block400not to move, while the weak spring601tries to move the moveable block400with a greater extend. As a result, the moveable block400only moves through a little distance. From physical calculation, the movement of the moveable block400is only K1/K2of the movement of the weak spring601. In this example, the movement of the moveable block400is only 1/100 of the movement of the weak spring601. Thus as the weak spring601moves through 10 μm (micrometer), the moveable block400will move through 0.1 μm. Thus, the moveable block400is fine-adjusted.

Furthermore, in the present invention, to reduce the vibration of the whole structure, a preload is added to the moveable block400. That is, in an assembly state, the strong spring602is deformed with a predetermined extent so as to apply a load to the moveable block400and thus the right metal sheet301and left metal sheet302will also deform with the same extent experienced by the moveable block400. The deformations of the right metal sheet301and the left metal sheet302are along a direction counter to that of the pushing forward direction of the weak spring601. This preload will cause that the structure of the present invention has the ability to prevent from vibration.

Moreover, it should emphasize that the present invention can prevent from the interference of friction force, that is, it is frictionless. In the present invention, the moveable block400, left metal sheet302and right metal sheet301are suspended and spaced from the upper surface101. They do not contact with the upper surface101of the platform100. In the driving operation of the weak spring601, the moveable block400, right metal sheet301and left metal sheet302are formed as a rigid body. No relative movement occurs between any two elements and thus no friction generates. The frictionless property is helpful to the precision of the system. As known in the art, the friction will reduce the precision due to the transfer of force is ineffective and the operator can not precisely estimate the effect of the friction. As a result, the precision of system is reduced. However the tricked design of the present invention has greatly reduced the effect of friction force.

In the second embodiment, as illustrated inFIG. 7, in this embodiment, those identical to the above embodiment will not be further described herein. Only those different from above embodiment are described. However all the elements of the second embodiment are identical to those in the first embodiment, only that no first rod501is used. The weak spring601is directly applied to the left metal sheet302. This also has the same effect as above said and thus the details will not be further described herein.

Referring toFIGS. 8 and 9, the effect of the present invention is illustrated. InFIG. 8, the data in first and second lines (viewed from left side) show the individual moving distance and the accumulated distance in each adjusting step by rotating the translation stage. The third lines shows a linear approximation of the data in the second line. The data in fourth line shows the differences between the second and third lines. In the second line ofFIG. 8, it shows that each moving step will cause a movement of the moveable block400to move through about 66 nanometers. This is suitable for the adjustment of optical elements. For example, a diameter of a core of a fiber is about 10 micrometers. Thus 66 nanometers is 1/150 of the diameter of the core. The step is small enough so that the optical element (optical fiber) can be precisely aligned.