Abstract:
A method and apparatus for optical aligning an electrical assembly includes inserting leads of an electrical assembly into guide holes of a nosepiece; guiding the leads exiting the nosepiece into a contact barrel; pressing the exiting leads with spring contacts that are electrically coupled to the leads; and moving the spring contacts along the leads to urge the electrical assembly toward the nosepiece.

Description:
TECHNICAL FIELD  
         [0001]    This disclosure relates to precise alignment of optical devices.  
         BACKGROUND  
         [0002]    High-speed communications often utilize opto-electronic (OE) devices. The opto-electronic devices on the receiver and transmitter sides of the communication system must be fabricated with a high degree of accuracy. Often the size of the communications systems may require that the opto-electronic devices be fabricated in large numbers. Assembly of the fiber optic filament and the devices typically requires that the device and fiber be coupled mechanically and optically. Typically this may involve sub-micron accuracy, performed manually by skilled technicians working with microscopes and high-precision manipulators. Once each opto-electronic device is assembled, it may be tested electrically to verify proper performance. Then the device is may be mounted onto a printed circuit board for connection to other electronic and optical signal processing components. Optical devices, such as lasers used in optical transmitters and photodiodes used in optical receivers, may be aligned during assembly to improve performance of the devices.  
           [0003]    A critical step in the assembly of transmitter and receiver optical subassemblies (TOSA &amp; ROSA) is the bonding of the devices to their housings. This step involves an active alignment (i.e. the TOSA/ROSA is operating during alignment) to close tolerances. Small variations in alignment may result in significant degradation of the opto-electronic device. To achieve this precise alignment and enable consistency of alignment between devices, the subassembly should be held in such a manner as to assure little or no movement in any of the horizontal or perpendicular axes.  
         SUMMARY  
         [0004]    In one aspect, a method of optical alignment an electrical assembly is disclosed that includes inserting leads of the electrical assembly into guide holes of a nosepiece; guiding the leads exiting the nosepiece into a contact barrel; pressing the exiting leads with spring contacts that are electrically coupled to the leads; and moving the spring contacts along the leads to urge the electrical assembly toward the nosepiece. The aforesaid method may also include causing the movement of the spring contacts by gas pressure.  
           [0005]    In second aspect, an apparatus for optical alignment of an electrical assembly is disclosed that includes a support block and a nosepiece located a fixed distance from the support block and including guide holes for electrical leads. Also included is a contact barrel movable between the support block and the nosepiece and a spring contact attached to the contact barrel and positioned to contact an electrical lead that exits the nosepiece wherein movement of the contact barrel causes the spring contact to move along the electrical lead.  
           [0006]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description, drawings and the claims.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0007]    FIGS.  1 A- 1 B illustrate a side view and a front view, respectively, of a precision alignment tool;  
         [0008]    FIGS.  2 A- 2 B illustrate a nosepiece of the tool of FIGS.  1 A- 1 B;  
         [0009]    [0009]FIG. 3 illustrates the alignment tool of FIGS.  1 A- 1 B in a load position; and  
         [0010]    [0010]FIG. 4 illustrates the tool of FIGS.  1 A- 1 B in a working position.  
         [0011]    Like reference symbols in the various drawings indicate like elements. 
     
    
     DETAILED DESCRIPTION  
       [0012]    FIGS.  1 A- 1 B illustrate a front view and a side view, respectively, of a precision alignment tool  100 . The alignment tool  100  includes a support subassembly  110 , an actuator subassembly  112  and a grip module subassembly  114 .  
         [0013]    Support subassembly  110  has a support plate  104  attached orthogonally to a mounting plate  102 . The mounting plate  102  may have holes, clips, pins or other such features for attaching the mounting plate  102  to an assembly fixture (not shown). The support plate  104  holds a gas actuator  106  capable of utilizing pressurized gas to cause movement of a cross-head plate  116  and including a pressure rod  108  coupled to the cross-head plate  116 . The gas actuator  106  may also include a gas port  142  for coupling of the gas actuator  106  to a source of pressurized gas (not shown). The support plate  104  also holds the actuator subassembly  112  and the grip module subassembly  114 .  
         [0014]    The actuator subassembly  112  has an actuator rod  118  with an upper end coupled to the cross-head plate  116 . The lower end of the actuator rod is coupled to a clamp block  132  that retains the grip module assembly  114 .  
         [0015]    The grip module assembly  114  has a contact barrel assembly  134  and a nosepiece  122 . The lower end of a support rod  120  is connected to the nosepiece  122 , and the upper end is connected to the support plate  104 . For high-production usage, the grip module assembly  114  may be adapted for rapid replacement in the clamp block  132 . Various configurations of the grip module assembly  114  may be used with different types of optical assemblies. The nosepiece  122  supports an optical assembly device under test (DUT). The grip module assembly  114  may also include a printed circuit board assembly or a connector (not shown) for coupling the alignment tool to the DUT and for providing receiving signals from the DUT.  
         [0016]    FIGS.  2 A- 2 B illustrate an implementation of a nosepiece assembly  122 . The nosepiece assembly may have a body  124  with guide holes  126  for guiding electrical leads of the DUT into the grip module assembly  114 . The nosepiece may have any shape that is compatible with the DUT. The guide holes may have chamfers to aid in the insertion of the DUT electrical leads. The nosepiece may have a number of guide holes in any relationship as necessary for the electrical leads of the DUT. The guide holes may be used to guide the DUT electrical leads into the contact barrel assembly  134 . The nosepiece body  124  also may have flats  128  that can guide the grip module assembly  114  into alignment with the nosepiece  122 . The nosepiece may have one or more nubs  130  of various shapes and sizes or other surface features or characteristics such as roughness, scribe lines, ridges and so on, that can be adapted to mate with a suitable surface on the DUT to aid in alignment of the nosepiece with the DUT. In an embodiment, the nosepiece  122  may include three nubs defining an alignment plane of the DUT. Referring again to FIGS.  1 A- 1 B, the contact barrel assembly  134  may include a contact barrel  136 . Spring contacts  138  are coupled to the contact barrel  136  and are arranged to provide electrical contact to the electrical leads  140  of the DUT. The contact barrel  136  further provides electrical coupling between the spring contacts  138  and the alignment station. The contact barrel assembly  134  is movable along support rod  120 .  
         [0017]    [0017]FIG. 3 illustrates the alignment tool in a start or load/unload position of an alignment cycle. Pressurized gas applied to the pressure port  142  of gas actuator  106  causes pressure rod  108  to pull cross-head plate  116  toward the gas actuator. Movement of the cross-head plate causes the actuator rod  118  to move the clamp block  132  to the full down position. The grip module assembly  114 , retained by the clamp block, also is moved to the load position.  
         [0018]    In the load/unload position, a DUT may be installed in the alignment tool. The electrical leads of the DUT can be inserted into the nosepiece  122  guide holes. The guide holes guide the DUT electrical leads  140  into the contact barrel  136  where the leads are gripped by the spring contacts  138 .  
         [0019]    [0019]FIG. 4 illustrates the alignment tool in a working position. Pressure may be supplied by the gas actuator  106  which moves the cross-head plate  116  up which in turn moves the actuator  118  up. Movement of the actuator moves the clamp block  132  and, in turn, the grip module assembly  114 , retained by the clamp block. The movement of the grip module assembly  114 , including the contact barrel  136 , is along the support rod  120  to the working position. The support rod holds the nosepiece  122  a fixed distance from the support plate  104 . Hence, movement of the contact barrel along the support rod exposes the electrical leads  140  of the DUT between the nosepiece  122  and the contact barrel  136 . In turn, spring contacts  138  slide along the DUT electrical leads. Pressure of the spring contacts sliding along the DUT electrical leads  140  tend to pull the DUT against the nosepiece and provide a holding force to retain the DUT in the alignment tool. The pressure of the contact springs may be selected to provide the holding and pulling force of the DUT so that the DUT is not damaged while maintaining electrical contact with the DUT electrical leads. The DUT is held in an alignment position against the nosepiece where the DUT may be precisely aligned.  
         [0020]    Release of the gas pressure from the actuator  106  causes return of the alignment tool to the load/unload position of FIG. 3. The movement of the spring leads  138  down the DUT electrical leads tend to move the DUT away from the nosepiece. The DUT may be removed from the alignment tool and the tool is then ready for another load/unload alignment cycle.  
         [0021]    Other implementations are within the scope of the following claims.