Abstract: A system bus (13) carrying multidimensional path data interfaces with a plurality of local microprocessors (24), one for each dimension, through a plurality of dual access memory structures (21), one for each local microprocessor (24). A local arbiter (35) controls access to each dual access memory structure (21), facilitating elimination of wait states in data transfers between the bus (13) and memory (21) and between the local microprocessor (24) and memory (21). The arbiter (35) is implemented using a programmable logic device state machine approach, which implements a mode of operation wherein the circuitry is armed for a transfer between a local microprocessor (24) and the dual access memory (21) and accomplishes such transfer with no wait states.

Abstract: Frequency stabilization in an RF excited carbon dioxide waveguide laser (10, 110, 210, 310) is obtained by employing as an imput to a dither stabilization feedback circuit (24, 124, 224, 324) an RF return power signal (62) that is a reflection of the exciting RF signal caused by mismatch of RF power source (14, 114, 214, 314) impedance and impedance of the laser cavity. The laser is operated so as to keep the RF return power from having its minimum magnitude. By employing an RF return power signal that is never at its minimum value, the system is insensitive to a wide range of thermal variation, and need for an optical laser output power sensor is eliminated.

Abstract: A laser cavity (12) subject to temperature induced effective length change greater than the length of a single power signature cycle of the laser is automatically stabilized by a combined digital arrangement for finding and locking on a selected signature peak corresponding to an optimum laser cavity length, and then digitally tracking such optimum length so as to stabilize operation at such peak. A piezoelectric crystal transducer (26) mounts one of the cavity mirrors (24) and is driven to change effective cavity length, first in an acquire mode, and then in a tracking mode. In acquire mode, voltage on the piezoelectric crystal transducer (26) is increased in a step wise linear fashion from near zero to a near maximum displacement of the crystal. A gain curve peak (33,34,35) is identified by sampling output power (30) of the laser, and storing the maximum value of sampled power, together with a peak transducer driving voltage at which such power maximum occurs.

Abstract: A grinding and polishing machine (11) which includes a grinding section (15), a polishing section (17), a fixture (19) and a fixture bearing assembly (21). Fiber optic termini (169) are retained in the fixture (19) so that distal ends (185) of optical fibers (177) and end faces (181) can be ground by a grinding abrasive (80) and polished by a polishing abrasive (91). The distal ends (185) and the end faces (181) prevent contact between the fixture (19) and the grinding abrasive (80) and the polishing abrasive (91).

Abstract: A multifaceted aluminum scanwheel 11 mounted for rotation on a steel bearing assembly 19 is made less susceptible to thermally-induced stresses by the provision of a specially-configured web section 17 that extends between the hub 15 and facet ring portions 13 of the wheel 11. A circumferential, slotted jog section 45 provides the flexibility to relieve compressive forces in the web 17 which might distort either the bearing assembly 19 or the scanwheel facet ring 13, or both.

Abstract: A raised metal connection feature (29) is created by forming a conductive pad (17) on a flexible substrate (11) and applying a flexible dielectric insulator (19) and photoresist layer (21) over the conductive pad (17). An excimer laser (25) is used to ablate a via (27) through the dielectric insulator (19) and photoresist (21) to the conductive pad (17). Gold or other metal is then plated up in the via (17), and the photoresist (21) is removed, leaving a metal feature (29) extending above the dielectric insulator (19).

Abstract: A lens type connector (13) comprising a connector body (31) having a passage (47) extending through it in an axial direction and a bushing (35) fixedly retained in the passage (47) of the connector body (31) and having a bushing passage (59) extending axially completely through the bushing. The bushing (35) has a radially inwardly projecting shoulder (61) in the bushing passage (59). A graded index rod (33) is movable axially in the passages (47, 59) so that an end face (77) of the graded index rod (33) can be urged against the shoulder (61) to at least assist in positioning and retaining the graded index rod (33) in the passages (47, 59).

Abstract: A strain relieving channel 32 is provided between the hub 31 of a multifaceted scanwheel 15 and the bearing assembly 13 on which the hub 31 is mounted. Compression of the bearing assembly 13 and distortion of the scanwheel facets 29 due to thermally induced compression of the scanwheel web 33 are both reduced by bowing of the hub 31, made possible by the strain relieving channel 32.

Abstract: An embedded polarizing beamsplitter employed in a liquid crystal light valve color projector introduces lateral chromatic aberration of complex distribution that degrades contrast and resolution of the projected image. Color correction is provided to substantially eliminate any noticeable lateral chromatic aberration by replacing the output window of the prism with an optical wedge made of the same material as the embedded prism plate of the beamsplitter.

Abstract: The transverse member (29) of a reflow soldering heater bar (23) is slotted at intervals to reduce thermal expansion. The slots (63), which typically extend orthogonally through the transverse member (29) and the connecting legs (61) of the heater bar (23), may extend diagonally therethrough to prevent missed welds.

Abstract: A fiber optic terminus (11) comprising a body (13) having a passage (43) therein and a longitudinally compressible and radially expandable coupling element (15) in the passage. The coupling element (15) has a passage (60) therein adapted to receive a portion of an optical fiber (23). An axial force is applied to the coupling element (15) by a plunger (17) and a spring (19). The coupling element (15) is compressed axially and expanded radially to retain the optical fiber (23) in the passage (60) of the coupling element.

Abstract: A force limiting weld head (11) which includes a supporting structure (13), a pressure barrel (15) and an output member (17) mounted for movement on the supporting structure, a fixed electrode (19) mounted on the supporting structure, a movable electrode (21) driven by the output member, a coupling (23) for drivingly coupling the pressure barrel and the output member. The coupling includes a variable-volume chamber (89) and a piston (77) responsive to overtravel for varying the volume of the chamber.

Abstract: A laser transmitter utilizes optical far field combination of two independent lasers (80,90) and variation of RF exciting power (86) to one (80) to produce sufficient frequency modulation. Two bores (122,124) within the same dielectric body (120) are provided with two independent sets of electrodes (134,135, 138,139) and two independent RF power sources (150,152). The lasers are operated at different frequencies and the beams transmitted in parallel adjacent paths to provide a combined far field optical beam component at the beat frequency of the two lasers. Variation of the frequency of one of the lasers provides frequency modulation of the far field beat frequency, enabling reception and demodulation of the modulated beam without use of a local oscillator laser at the receiver. The transmitter may also be used in a laser radar.

Abstract: A digital robotic axis controller which employs a digital processor to apply the inverse of a plant model transfer function to positional information representative of a target path to generate a feed forward position control signal and to combine an error signal with the positional information to generate a feedback control signal. The feed forward and feedback control signals are combined to produce a total position control signal which is supplied to a digital-to-analog converter and then to a plant comprising an amplifier, a motor for establishing the actual position of a robotic member, and an encoder for deriving the error signal from the motor position. In application, a number of such plants are controlled to achieve a coordinated multidimensional movement with increased accuracy.

Abstract: A mode preserving apparatus (11) comprising a supporting structure (13), an optical fiber (15), a pin connector (17) for positioning a first region of the optical fiber at a first location and a strain-relief mechanism (19) for positioning a second region of the fiber at a second location. A bobbin assembly (21), includng a first bobbin (23), is mounted on the supporting structure (13) for movement relative to the first and second locations. The optical fiber (15) extends along a path from the first location at least part way around the bobbin (23) to the second location so that movement of the bobbin (23) relative to the first and second locations alters the configuration of the path.

Abstract: An apparatus (11) comprising a mother board (13), a daughter board (15), an electrical connector pair (17) and an optical connector pair (19). The connector pair (17) includes electrical connectors (23, 27) mounted, respectively, on the mother board (13) and the daughter board (15), and the optical connector pair (19) includes connectors (31, 33) mounted, respectively, on the mother board (13) and the daughter board (15). The optical connector (31) is mounted on the mother board (13) for movement toward and away from the optical connector (33). The daughter board (15) can be moved toward the mother board (13) to mate the electrical connectors (23, 27). Subsequently, a screw (21) is rotated to move the optical connector (31) into mating relationship with the optical connector (33).

Abstract: A grinding and polishing machine (11) which includes a grinding section (15), a polishing section (17), a fixture (19) and a fixture bearing assembly (21). Fiber optic termini (169) are retained in the fixture (19) so that distal ends (185) of optical fibers (177) and end faces (181) can be ground by a grinding abrasive (80) and polished by a polishing abrasive (91). The distal ends (185) and the end faces (181) prevent contact between the fixture (19) and the grinding abrasive (80) and the polishing abrasive (91).

Abstract: Laser soldering in a tape automated bonding procedure is carried out on outer ends of a number of high density leads (72) printed on a film (78) of mylar and having inner ends connected to a circuit chip (70). The outer ends of the leads are soldered, without the use of flux, by application of heat and ultrasonic energy in a timed program while pressing an end (52) of the lead to be soldered against the substrate pad to which it is to be soldered. An elongated ultrasonically vibratable capillary (16) is employed to press the wire down against its pad (54) and to receive and guide an optical fiber (44) through which a beam of laser energy is fed coaxially through the capillary (16) to heat the wire end (52).

Abstract: A method for restricting the mode of operation of long wavelength waveguide laser (FIG. 1) by introducing an approximate step function into the reflectivity of circular optical elements (19) used in such lasers. The preferred method is to grind off a portion of the optical coating (20) of the optical element (19) leaving a circular unground region (26) of high reflectivity having a diameter (D) of approximately 60% of the laser bore width (b) bounded by a ground region (28) of lower reflectivity. The method permits simple, inexpensive field modification of existing lasers.

Abstract: A digital servo system for causing a mechanical element (48) to track a desired path and hold various positions along the path and employing a lead/lag integrator (18) in parallel with a feedback control loop. The input to the integrator (18) is switched between velocity (V.sub.EK) error during pathtracking and position error (E.sub.K) during holding to increase the resistance of the mechanical element (48) to position changes caused by outside forces during both pathtracking and holding. The integrator function employed uses a term (U.sub.integrator(k-1)) representing a previous integrator output value to assist in smoothing perturbations caused by switching between position and velocity error.