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.LM 10 .CHAPTER CHAPTER-V .SKIP 2 V. LIGHT COLLECTOR SUBSYSTEM .SKIP 2 A. REFERENCES .SKIP 2 B. FUNCTION .SKIP 2 C. DESCRIPTION .SKIP 2 D. OPERATION .SKIP 2 E. MAINTENANCE .SKIP 2 E.1 PERIODIC .SKIP 2 E.2 CORRECTIVE .SKIP 2 E.3 OPTICAL ALIGNMENT PROCEDURES .SKIP 2 E.4 PA CARD MALRFUNCTION .SKIP 2 E.5 PM TUBE REPLACEMENT .SKIP 2 E.6 EXCESSIVE AMBIENT LIGHT .PAGE
.LM 5 V. LIGHT-COLLECTOR SUBSYSTEM .BR ------------------------------- .SKIP 2 A. REFERENCES .BR --------------- .SKIP .LIST FIGURE 4 - "OPTICAL ARRANGEMENT" .SKIP DWG. 2147M1 - "DRIVE SIDE AND PM SIDE ARRANGEMENT" .SKIP DWG. 2147M2 - "EXIT END ARRANGEMENT" .SKIP DWG. 2147M5 - "TRANS. COLLECTOR ARRANGEMENT" .SKIP DWG. 2147M6 - "REFLECT. COLLECTOR ARRANGEMENT" .SKIP DWG. 2147M12 - "PHOTOMULTIPLIER TUBE ASSEMBLY" .SKIP DWG. 2147M23 - "BEAM SPLITTER ASSEMBLY" .SKIP DWG. 2147M8 - "BEGINNING OF SCAN ADJ. APERTURE" .SKIP DWG. 2147M9 - "END OF SCAN ADJ. APERTURE" .SKIP .END LIST
.COMMENT PAGE 17 B. FUNCTION .BR ------------- .SKIP THE PURPOSE OF THIS SUBSYTEM IS TO: .SKIP .LIST .INDENT -3 *##COLLECT THE SCANNING BEAM ENERGY THAT IS TRANSMITTED THROUGH AND REFLECTED FROM THE PRODUCT UNDER INSPECTION. .SKIP .INDENT -3 *##LINEARLY CONVERT THIS OPTICAL ENERGY INTO TWO ELECTRICAL SIGNALS WHOSE TIME-VARING AMPLITUDES CORRESPOND TO THE VARIATIONS IN OPTICAL ENERGY TRANSMITTED THROUGH AND REFLECTED FROM THE PRODUCT. .SKIP .INDENT -3 *##AFTER TWO STAGES OF AMPLIFICATION ON THE PA CARD LOCATED IN THE PHOTOMULTIPLIER TUBE HOUSING, THESE SIGNALS ARE CALLED THE REFLECTION PA AND TRANSMISSION PA SIGNALS. THE AMPLIFICATION BRINGS THE SIGNALS UP TO A LEVEL (-1.2 V) SUFFICIENT TO TRANSMIT THEM OVER SHIELDED CABLES TO THE CHANNEL DRAWERS IN THE MAIN ELECTRONIC CONSOLE. .SKIP .END LIST C. DESCRIPTION .BR ---------------- .SKIP THIS SUBSYSTEM IS LOCATED IN THE BOTTOM SECTION OF THE FRAMEWORK. THE COLLECTORS ARE MOUNTED ON SLIDE ASSEMBLIES FOR EASE OF ACCESS FROM THE AISLE SIDE OF THE INSPECTOR (SEE FIG. 4 AND DWG. M1, M2, M5, AND M6). SINCE BOTH COLLECTORS ARE SIMILIAR IN DESIGN, THE TRANSMISSION COLLECTOR WILL BE DESCRIBED FULLY AND DIFFERENCES NOTED WHEN APPROPIATE. AS NOTED PREVIOUSLY THE LASER-BEAM ENERGY IS COLLECTED BY THE ROD COLLECTOR MOUNTED IN THE COLLECTOR HOUSING. THE RODS ARE CLEAR ACRYLIC, TAPERED FROM 3 IN. DIAMETER AT THE AISLE (PM TUBE) SIDE TO 2 IN. DIAMETER AT THE DRIVE SIDE OF THE INSPECTOR FRAME. OVERALL ROD LENGTH IS 174 IN. THE LASER-BEAM ENERGY THAT HAS ENTERED THE ROD IS FOCUSED ON A THIN WHITE STRIPE RUNNING ALONG THE LENGTH OF THE OF THE REAR SURFACE OF THE ROD. THIS STRIPE ACTS AS A DIFFUSING SURFACE TO SCATTER THE LIGHT IN ALL DIRECTIONS. SOME RAYS SO PRODUCED ARE TRAPPED WITHIN THE ROD AND PROPAGATE TOWARDS A SINGLE PHOTOMULTIPLIER TUBE LOCATED AT THE LARGER DIAMETER END OF THE ROD. .SKIP FIXED APERTURES ARE USED TO LIMIT THE ROD'S FIELD OF VIEW AND TO MASK AREAS OF THE ROD FOR AUTOMATIC CALIBRATION OR SELF-CHECK FEATURES. THESE APERTURES IN THE COLLECTOR HOUSING ARE COVERED BY WINDOWS SERVING TWO FUNCTIONS: .SKIP .LIST .INDENT -3 *##THEY PROTECT THE ROD FROM DAMAGE AND ENTRY OF DIRT. .SKIP
.COMMENT PAGE 18 .SKIP .INDENT -3 *##THE SELF-CHECK WINDOW HAS PROVISIONS FOR REPLACEABLE OPTICAL FILTERS. EACH PRODUCT TYPE MAY REQUIRE A DIFFERENT FILTER TO OBTAIN THE PROPER SELF-CHECK SIGNAL HEIGHT (SEE SEC. 4.4 FOR DETAILS). .SKIP .END LIST BEGINNING AND END-OF-SCAN ADJUSTABLE APERTURES (OR MASKS) ARE LOCATED ABOVE BOTH COLLEDTORS, ONE ON EITHER END OF THE FRAME (DWG. M8 AND M9). THE POSITIONS OF THESE MASKS ARE INDEPENDENTLY ADJUSTABLE AND MUST BE SET BY THE OPERATOR TO RESTRICT THE SCAN BEAM TO AT LEAST 2 IN. LESS THAN THE FULL WEB WIDTH ON BOTH SIDES. OBSERVATION AND REMOTE CONTROL OF THESE MASK POSITIONS ARE ACCOMPLISHED AT THE MAIN CONSOLE. IF THIS IS IMPROPERLY SET OR THE EDGE WANDERS OUT PAST EITHER MASK, THE INSPECTOR WILL INTERPRET THIS AS A DEFECTIVE WEB ZONE. AT MINIMUM MASK, THE SCAN BEAM WILL INSPECT 154 IN. OF WEB WIDTH; AT MAXIMUM MASK, THE SCAN BEAM WILL TRAVERSE 136 IN. (68 IN. ON EITHER SIDE OF THE PROCESS LINE CENTERLINE). .SKIP NOTE THAT IF EITHER: .SKIP .LIST .INDENT -3 *##THE OVERALL WEB WIDTH IS LESS THAN 136 IN., OR .SKIP .INDENT -3 *##A 136 IN. WEB IS NOT CENTERED, THE INSPECTOR WILL CONSIDER THE WEB DEFECTIVE. .SKIP .END LIST A BEAM-SPLITTER ASSEMBLY IS FIXED TO THE DRIVE SIDE OF THE TRANSMISSION COLLECTOR HOUSING ABOVE THE SELF-CHECK APERTURE (DWG. M5 AND M23). ITS PURPOSE IS TO PASS 50% OF THE SCAN-BEAM ENERGY TO THE TRANSMISSION ROD SELF-CHECK APERTURE AND REFLECT 50% UP TO THE REFLECTION ROD'S APERTURE. THIS IS NECESSARY SINCE THE SCAN BEAM IS OFF THE PRODUCT AT THIS POINT IN THE SCAN. .SKIP A RED FILTER, PHOTOMULTIPLIER TUBE, DC-TO-DC CONVERTER, AND PREAMPLIFIER CARD ARE LOCATED INSIDE EACH PM HOUSING (DWG. M12). THE HOUSING IS COUPLED TO THE AISLE END OF THE COLLECTOR ASSEMBLY BY MEANS OF AN ACCORDIAN-TYPE BOOT AND GILLIMAN SLIDE. THE PURPOSE OF EACH MAJOR COMPONENT IS AS FOLLOWS. .SKIP .SKIP .LIST .INDENT -3 *##RED FILTER ATTENUATES AMBIENT LIGHT (NONLASER LIGHT). AN EXCESS OF AMBIENT LIGHT REACHING THE PHOTOMULTIPLIER TUBE WOULD CAUSE 60-HZ MODULATION NOISE ON THE INSPECTION PA SIGNAL. .SKIP .INDENT -3 *##PHOTOMULTIPLIER TUBE (PM) CONVERTS OPTICAL ENERGY TO ELECTRICAL SIGNAL. .SKIP .INDENT -3 *##DC-TO-DC CONVERTERS CHANGE LOW-VOLATGE DC POWER FROM THE PA CARD TO HIGH-VOLTAGE DC POWER NECESSARY TO OPERATE THE PM TUBE. THIS CONVERTION IS AT A CONSTANT RATIO OF 1:100, I.E., 9V INPUT PRDUCES 900V OUTPUT. .SKIP
.COMMENT PAGE 19 .INDENT -3 *##PREAMPLIFIER CARD (PAU) AMPLIFIES THE PM SIGNAL, AND THROUGH AN AUTOMATIC-GAIN-CONTROL (AGC) CIRCUIT, STANDARDIZES THE OUTPUT SIGNAL (PA) TO A 1.2 VOLT LEVEL; THEN BUFFERS THIS SIGNAL TO DRIVE THE PM HOUSING/MAIN CONSOLE SIGNAL CABLE. .SKIP .INDENT -3 *##THE GILLIMAN SLIDE ENABLES ONE TO ADJUST THE DISTANCE BETWEEN THE END OF THE ROD AND THE FACE OF THE PM TUBE. THIS, ALONG WITH AN ADJUSTABLE DISC AT THE OTHER END OF THE ROD, HAS BEEN ADJUSTED TO OBTAIN AN OPTIMALLY FLAT TOP ON THE PA SIGNAL WHEN INSPECTING GOOD PRODUCT. .SKIP .END LIST D. OPERATION .BR -------------- .SKIP OTHER THAN THE CORRECT POSITIONING OF THE BEGINNING AND END SCAN APERTURES AND PERIODIC CHANGES OF THE NEUTRAL DENSITY FILTER, THERE ARE NO SWITCHES, ADJUSTMENTS, OR CONTROLS TO BE SET TO OPERATE THIS SUBSTEM. .SKIP SETTING OF THE SCAN APERTURES IS COVERED IN THE SYSTEM OPERATING PROCEDURES. .SKIP THE NEUTRAL-DENSITY (ND) FILTER, OR A PIECE OF PRODUCT USED AS SUCH, MUST NORMALLY BE CHANGED WHEN SWITCHING PRODUCTION FROM ONE PRODUCT TYPE TO ANOTHER, OR WHEN LARGE CHANGES IN PRODUCT BASIS WEIGHT ARE MADE. IN A NORMALLY OPERATING SYSTEM, THE HEIGHT OF THE SIGNAL RESULTING FROM THE LASER BEAM'S ENTERING THE SELF-CHECK APERTURE IS CHECKED FOR AMPLITUDE. THE ND FILTER OR A PIECE OF PRODUCT IN PLACE OF THE BEAM SPLITTER IS SELECTED TO PRODUCE A SIGNAL PEAK EQUAL TO THE PEDESTAL HEIGHT. SINCE THE DENSITY OF THE PRODUCT BEING INSPECTED INDIRECTLY AFFECTS THIS PULSE HEIGHT (THROUGH THE AGC CIRCUIT OF THE PAU CARD), THE FILTER MUST BE CHANGED IN COMPENSATION IF THE SELF-CHECK PULSE IS LESS THAN THE PEDESTAL. .SKIP ONCE EACH SCAN, THE ELECTRONICS CHECKS FOR THE PRESENCE OF THE SELF-CHECK PULSE. IF THE SELF-CHECK SIGNAL IS BELOW 0.4V, A SELF-CHECK ALARM WILL RESULT. .SKIP E. MAINTENANCE .BR ---------------- .SKIP 2 E.1 PERIODIC .BR --------------- .SKIP EXCEPT FOR GLASS AND WINDOW CLEANING, NONE SHOULD BE REQUIRED (SEE SECTION 3.5.1 FOR CLEANING TECHNIQUES). .SKIP 2
.COMMENT PAGE 20 E.2 CORRECTIVE .BR ----------------- .SKIP THE NEED FOR CORRECTIVE MAINTENANCE WILL GENERALLY BE INDICATED BY ONE OF THE FOLLOWING: .SKIP .LIST .INDENT -3 *##CHECKS OUTLINED IN SECTION 3.5.2 HAVE BEEN MADE BUT PROBLEM PERSISTS. .SKIP .INDENT -3 *##OBSERVATION OF THE SCAN LINE INSIDE ROD COLLECTOR INDICATES THAT IT IS NOT TRACKING THE WHITE STRIP OVER THE LENGTH OF THE ROD. UPPER BEAM-FOLDING MIRROR ADJUSTMENT MAYBE REQUIRED. .SKIP .INDENT -3 *##PA SIGNAL IS NOT REGULATING AT THE 1.2V SIGNAL LEVEL, OR THERE IS EXCESSIVE 60-HZ MODULATION (> PLUS OR MINUS 0.5V) OF THE PA SIGNAL. THE PA CARD OR PM TUBE MAY BE FAULTY, OR THERE MAY BE EXCESSIVE AMBIENT LIGHT AROUND THE COLLECTORS. .SKIP .END LIST E.3 OPTICAL ALIGNMENT PROCEDURES .BR ------------------------------------- .SKIP OPTICAL ALIGNMENT PROCEDURES ARE DESCRIBED IN SECTION 3.5.2.1. .SKIP 2 E.4 PA CARD MALFUNCTION .BR ---------------------------- .SKIP PA CARD MALFUNCTION REQUIRES THE FOLLOWING ACTION: .SKIP .LIST .INDENT -3 *##TURN OFF THE DC POWER TO PM HOUSING. .SKIP .INDENT -3 *##REMOVE PM HOUSING COVER AND PULL PAU CARD. .SKIP .INDENT -3 *##SUBSTITUTE SPARE CARD, REPLACE COVER, REAPPLY POWER. .SKIP .END LIST
.COMMENT PAGE 21 E.5 PM TUBE REPLACEMENT .BR ---------------------------- .SKIP PM TUBE REPLACEMENT INVOLVES THE FOLLOWING STEPS: .SKIP .LIST .INDENT -3 *##TURN OFF DC POWER TO PM HOUSING. .SKIP .INDENT -3 *##DISCONNECT ALL POWER AND SIGNAL CABLE CONNECTORS AT THE PM HOUSING. .SKIP .INDENT -3 *##REMOVE PURGE AIR FITTING. .SKIP .INDENT -3 *##REMOVE FOUR CAP SCREWS HOLDING PM HOUSING TO THE GILLIMAN SLIDE BRACKET. BE SURE TO SUPPORT THE HOUSING SO THAT IT DOES NOT DROP. .SKIP .INDENT -3 *##FROM THE FRONT OF THE HOUSING, CAREFULLY REMOVE THE RED FILTER COVERING THE HOUSING BARREL. .SKIP .INDENT -3 *##REACH INTO THE HOUSING BARREL AND PULL THE PM TUBE OUT OF THE HOUSING SOCKET. .SKIP .INDENT -3 *##REPLACE WITH SPARE PM TUBE. .SKIP .INDENT -3 *##REASSEMBLE UNIT. .SKIP .END LIST E.6 EXCESSIVE AMBIENT LIGHT .BR -------------------------------- .SKIP EXCESSIVE AMBIENT LIGHT MAY BE CAUSED BY: .LIST .INDENT -3 *##OPEN INSPECTION ACCESS DOOR ON THE FRAME. MAKE SURE ALL DOORS ARE CLOSED. .SKIP .INDENT -3 *##DISLODGED PM TUBE FILTER. FOLLOW PROCEDURE 4.5.2.3 TO EXAMINE AND REPLACE IF NECESSARY. .SKIP .END LIST .CHAPTER CHAPTER VI .PAGE