Zero clearance optical fiber bundle coupler focusing mechanism
Technical Field
The invention belongs to the field of optical fiber bundle couplers, and particularly relates to a zero-gap optical fiber bundle coupler focusing mechanism.
Background
In a confocal imaging system based on an optical fiber bundle, a laser emits laser, the end face of the optical fiber bundle is scanned through a laser scanning device and a coupling objective lens, the laser is focused and then injected into each fiber core of the optical fiber bundle, and the diameter of each fiber core is about 2-3 microns. At the other end of the optical fiber bundle, the injected laser is focused on an observed object through a micro objective lens, the observed object emits fluorescence under the excitation of the injected laser, and the fluorescence returns through the fiber core of the optical fiber bundle along the same path and is finally captured and imaged by a detector. The coupling objective lens and the optical fiber bundle need to be accurately positioned, and small distance deviation can cause large fluctuation of imaging quality, so that the accurate positioning and stable maintenance of the focusing mechanism are particularly important for ensuring the normal work of the system.
Chinese patent publication No. CN107065077A discloses an auto-focusing positioning optical fiber bundle coupler, which includes a coupler socket for mounting a coupler plug, the plug has a positioning head, and is matched with a plug positioning groove on the coupler socket, so that the end surface of the positioning head is matched with a corresponding plane of a connecting sleeve, and the optical fiber bundle is ensured to be perpendicular to the axis of the connecting sleeve; the coupler plug is used for accommodating an optical fiber bundle, the coupler socket is provided with an objective lens sliding groove corresponding to the plug positioning groove, and the coupling objective lens is controlled to slide on the objective lens sliding groove, receive a signal from the optical fiber bundle and transmit the signal to the confocal imaging system; the automatic focusing positioning is realized by judging the relative position relationship between the coupling objective lens and the section of the optical fiber bundle and controlling the sliding of the coupling objective lens in a feedback manner until the optimal coupling position is found.
The focusing device of the patent uses the motor with the step length smaller than 1 micron, but because the electrode is a linear motion pair, the gap is smaller, the gap of the linear motion pair of the coupling objective lens is also smaller, the motor is rigidly connected with the coupling objective lens, the direction of the two linear motion pairs of the motor and the coupling objective lens can be ensured to be consistent without interference by extremely strict adjustment, and the adjustment difficulty is extremely high.
Disclosure of Invention
Aiming at the defects or the improvement requirements of the prior art, the invention provides a zero-gap optical fiber bundle coupler focusing mechanism, aiming at solving the technical problem that the coupling objective lens in the prior art is difficult to install and adjust.
In order to achieve the above object, the present invention provides a focusing mechanism for a zero-gap optical fiber bundle coupler, which includes an optical fiber bundle coupler and a confocal probe, wherein the optical fiber bundle coupler includes a base, a connecting sleeve, an objective lens sleeve and a coupled objective lens, the confocal probe includes a plug base, a plug sleeve and an optical fiber bundle, a sliding table is slidably disposed on an upper end surface of the base along an axial direction of the objective lens sleeve, an elastic member is connected between the sliding table and the objective lens sleeve, the elastic member includes a rigid connecting end and a flexible connecting end, the rigid connecting end of the elastic member is rigidly connected with the sliding table, the flexible connecting end of the elastic member is rigidly connected with the objective lens sleeve, and the elastic member is in a stretching state so as to make the flexible connecting end of the elastic member flexibly contact with the sliding table.
Through the technical scheme, the movement of the coupling objective lens is connected with the movement of the sliding table through the elastic piece, the flexible contact end of the elastic piece is in flexible contact with the sliding table, and movement interference caused when the movement axis directions of the elastic piece and the sliding table are inconsistent can be avoided, so that the axial gap of the whole focusing mechanism is close to zero, accurate coupling is realized, and accurate focusing can be still kept under the condition of vibration interference.
Preferably, the up end of slip table has the push pedal through the fix with screw, flexible connection end includes threaded connection the objective cover is kept away from the removable pin of fiber bundle one end, the push pedal is close to the one end of objective cover is seted up flutedly to the direction of keeping away from the objective cover.
Preferably, the inner wall of recess is the cambered surface, the lower extreme of activity round pin is located in the recess, the activity round pin with the inner wall flexible contact of recess just the length and the width of recess all are greater than the external diameter of activity round pin.
Preferably, the upper end face of the movable pin is connected to the lower end of the objective sleeve through threads, and the lower end face of the movable pin is located in the groove and higher than the lower end face of the push plate.
Preferably, the rigid connection end includes threaded connection the fixed pin of push pedal up end, the fixed pin with the waist groove has all been seted up in the same high department to the lateral wall of activity round pin, the winding of both ends of elastic component is respectively through the waist groove the fixed pin with week side of activity round pin.
Preferably, a pedestal is further fixed to the upper end face of the base, the sliding table slides linearly on the pedestal, and the pedestal is rigidly connected to the base through screws.
Preferably, an objective sliding groove used for mounting the objective sleeve is formed in the connecting sleeve, a positioning groove used for mounting the plug seat is formed in one end, far away from the objective sliding groove, of the connecting sleeve, a positioning device matched with the positioning groove for mounting the plug seat is arranged on the base, the objective sliding groove and the positioning groove are vertically restrained, and the verticality is smaller than 5 microns.
Drawings
FIG. 1 is a cross-sectional view of a zero-gap fiber bundle coupler focusing mechanism;
FIG. 2 is an overall block diagram of a zero-gap fiber bundle coupler focusing mechanism.
In the figure, 1, a fiber bundle coupler; 11. a base; 12. connecting sleeves; 13. a coupling objective lens; 14. an objective lens sleeve; 15. a movable pin; 16. an elastic member; 17. a fixing pin; 18. pushing the plate; 181. a groove; 19. a linear motor; 191. a pedestal; 192. a sliding table; 2. a confocal probe; 21. a plug base; 22. a plug cover; 23. an optical fiber bundle.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example one
As shown in fig. 1, the present embodiment discloses a zero-gap optical fiber bundle coupler focusing mechanism, which includes an optical fiber bundle coupler 1 and a confocal probe 2, wherein the optical fiber bundle coupler 1 includes a base 11, a connecting sleeve 12, an objective lens sleeve 14 and a coupling objective lens 13, and the confocal probe 2 includes a plug socket 21, a plug sleeve 22 and an optical fiber bundle 23.
The base 11 is shaped like L, the connecting sleeve 12 is rigidly connected to the base 11 by screws, the connecting sleeve 12 is provided with an objective sliding groove, the objective sliding groove is parallel to the axis of the connecting sleeve 12, the objective lens 14 is installed in the connecting sleeve 12 and can slide along the axis of the connecting sleeve 12 through the objective sliding groove, the coupling objective 13 is rigidly connected in the objective lens 14 by screw threads, the connecting sleeve 12 is provided with a positioning groove at one end far away from the objective sliding groove, the positioning groove is used for inserting and positioning the plug base 21 of the confocal probe 2, the plug sleeve 22 is screwed on the end of the plug base 21, the plug base 21 is provided with a through hole, the optical fiber bundle 23 penetrates into the through hole to be bonded with the plug base 21, the end surface of the optical fiber bundle 23 is flush with the end surface of the plug base 21, the end of the plug base 21 far away from the end flush with the optical fiber bundle 23 is screwed with the plug sleeve 22, and the plug sleeve 22 surrounds the outer side of the optical fiber bundle.
An optimal observation plane exists on one side of the coupling objective lens 13 close to the optical fiber bundle 23, the plane is a plane which is perpendicular to the optical axis of the coupling objective lens 13 and has the diameter of 1-2 mm, the end face of the optical fiber bundle 23 must be overlapped with the plane, the axial error does not exceed +/-5 microns, the image can be clearly imaged, and otherwise, the image can be blurred in a partial range or a whole range. Therefore, ensuring that the end face of the optical fiber bundle 23 connected to the plug receptacle 21 is in the best viewing plane of the coupling objective 13 is critical to achieving accurate focusing of the system.
One side of the base 11 close to the optical fiber bundle 23 is provided with a positioning device, before the optical fiber bundle coupler 1 works, the plug sleeve 22 is held, the plug base 21 and the optical fiber bundle 23 are inserted into the positioning groove of the connecting sleeve 12 until the plug base 21 abuts against the end face of the positioning groove, after the plug base 21 is installed, the positioning device can be a fixed component in the patent publication No. CN107065077A or a pressing device in the patent publication No. CN108761653B, the position of the plug base 21 is positioned and locked through the positioning device, and the phenomenon that the plug base 21 shakes to affect the focusing result in the later focusing process is avoided.
The object lens sliding groove of the connecting sleeve 12 and the end surface of the positioning groove have verticality constraint, the verticality constraint is less than 5 mu m, the matching precision between the object lens sliding groove of the connecting sleeve 12 and the object lens sleeve 14 and between the object lens sleeve 14 and the coupling object lens 13 is H6/H5, and the optical axis of the coupling object lens 13 can be ensured to be perpendicular to the end surface of the positioning groove after the coupling object lens 13 is installed. The flatness of the end face of the plug holder 21 in the positioning groove is less than 5 micrometers so as to coincide with the end face of the positioning groove, and finally the end face of the optical fiber bundle 23 is parallel to the optimal observation plane of the coupling objective lens 13.
The linear motor 19 is fixed on the upper end face of the base 11, the linear motor 19 comprises a pedestal 191 fixed on the upper end face of the base 11 and a sliding table 192 linearly sliding on the pedestal 191, and the pedestal 191 is fixed on the base 11 through screws and is rigidly connected with the base 11. The upper end surface of the sliding table 192 is rigidly connected with a push plate 18 through a screw, an elastic member 16 is connected between the push plate 18 and the coupling objective 13, and the elastic member 16 may be a tension spring, a rubber band, a spring rope or other types of springs.
The two ends of the elastic member 16 respectively include a rigid connection end and a flexible connection end. The rigid connection end is a fixing pin 17, the flexible connection end is a movable pin 15, waist grooves are formed in the same height positions on the peripheral walls of the fixing pin 17 and the movable pin 15, and two ends of the elastic piece 16 are wound on the peripheral sides of the fixing pin 17 and the movable pin 15 through the waist grooves respectively, so that the fixed connection end and the flexible connection end are formed.
The fixed pin 17 passes through the up end of screw thread rigid connection at push pedal 18, the lower extreme that the movable pin 15 is close to fixed pin 17 one side at objective cover 14 through screw thread rigid connection, one side that the push pedal 18 is close to objective cover 14 is seted up flutedly 181 to the direction of keeping away from objective cover 14, the inner wall of flutedly 181 is the cambered surface, whole recess 181 is the U font, movable pin 15 is cylindricly, the length and the width of recess 181 all are a bit more than the external diameter of movable pin 15, the lower extreme of movable pin 15 is located the recess 181 and the lower terminal surface of movable pin 15 is higher than the lower terminal surface of push pedal 18, elastic component 16 is in the state of being stretched all the time, through elasticity pulling movable pin 15 butt on the inner wall that recess 181 is close to fixed pin 17 one side, thereby make be flexible contact between movable pin 15 and the push pedal 18, movable pin 15 can be the self.
Example two
The embodiment discloses a focusing method of a zero-gap optical fiber bundle coupler, which is based on a focusing mechanism disclosed by the first embodiment and comprises the following steps:
s1, holding the plug bush 22, inserting the plug base 21 and the optical fiber bundle 23 into a positioning groove in the connecting sleeve 12, wherein the end face of the plug base 21 abuts against the end face of the positioning groove, and then positioning and locking the position of the plug base 21 by using a positioning device; the recoupling objective lens 13 is arranged in the objective lens sleeve 14, and the objective lens sleeve 14 is arranged in the connecting sleeve 12; after the installation is finished, the end surface of the optical fiber bundle 23 close to the objective lens is parallel to the optimal observation surface of the coupling objective lens 13;
s2, the linear motor 19 resets the zero position, so that the sliding table 192 moves to the farthest position in the direction away from the optical fiber bundle 23 until the sliding table abuts against the pedestal 191;
s3, the linear motor 19 drives the sliding table 192 to move gradually in the direction close to the optical fiber bundle 23 in steps less than 5 μm, each time the movement advances, the end face image of the optical fiber bundle 23 acquired by each step of the coupling objective lens 13 is analyzed, for different axial positions of the coupling objective lens 13, the difference of sharpness of the end face image of the optical fiber bundle 23 is compared, and the position with the highest sharpness, namely the pole position where the sharpness starts to decline, is found, namely the best focusing position of the coupling objective lens 13;
when the sliding table 192 moves gradually towards the direction close to the optical fiber bundle 23, the fixing pin 17 of the push plate 18 is driven to move together, because the movable pin 15 abuts against the inner wall of the groove 181, the push plate 18 also pushes the movable pin 15 to approach the optical fiber bundle 23 at the same time, and finally the objective sleeve 14 is pushed by the movable pin 15 to slide along the direction of the objective sliding slot, so that the coupling objective 13 gradually approaches the optical fiber bundle 23.
In the whole focusing process, the sliding table 192, the push plate 18 and the fixing pin 17 are in rigid connection, and the objective lens sleeve 14 and the movable pin 15 are also in rigid connection, so that the sliding table 192, the push plate 18 and the fixing pin 17 can move along the same straight line without axial gaps; the objective sleeve 14 and the movable pin 15 also move along the same straight line without axial clearance; and a certain axial clearance exists between the two linear motions, the elastic piece 16 is connected between the two linear motions, and the clearance deviation of the crossed axes between the two linear motions is compensated through the sliding of the movable pin 15 in the groove 181, so that the motion interference and the blocking caused by the crossed axes can not occur. The linear motor 19 can adopt precision driving equipment such as a stepping motor, a servo motor, a voice coil motor, a piezoelectric ceramic driver and the like, and the moving step length and the movement pair clearance of the linear motor are both smaller than 1 micron or reach the nanometer precision. Even if the linear motor 19 generates vibration interference, the coupling objective 13 still can linearly approach the optical fiber bundle 23 along the objective sliding groove along with the objective sleeve 14 until the optimal observation plane is superposed with the end face of the optical fiber bundle 23, so that accurate focusing is realized, and clear imaging is ensured. Meanwhile, because the elastic force of the elastic element 16 directly acts between the movable pin 15 and the fixed pin 17, the resistance of the linear motor 19 is not additionally increased, so that the movement of the sliding table 192 is more stable during focusing, and the positioning is more accurate.
Because each step of the movement of the coupling objective lens 13 close to the optical fiber bundle 23 is imaged, the position of each step and the corresponding image are stored through software, when the movement of the coupling objective lens 13 close to the optical fiber bundle 23 exceeds the optimal focusing position, the sharpness of the image begins to decrease, the linear motor 19 drives the sliding table 192 to move in the direction away from the optical fiber bundle 23, the sliding table 192 directly returns to the position corresponding to the highest sharpness of the image stored by the software, namely the optimal focusing position, and when the sliding table 192 drives the fixing pin 17 to return, the movable pin 15, the objective lens sleeve 14 and the coupling objective lens 13 follow the direction away from the optical fiber bundle 23 through the elastic force of the elastic piece 16, so that the focusing operation is completed.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.