Application Note 5088 Introduction safety calculations presented

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Application Note 5088 Introduction safety calculations presented

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Agilent ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 Laser Mouse Sensor Safety Calculations
Application Note 5088
Introduction safety calculations presented this application note apply Agilent Laser mouse sensor bundles ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012. Agilent laser sensor bundles made following parts: laser mouse sensor (ADNS-6000 ADNS-6010), optical lens (ADNS-6120 ADNS-6130-001), lens clip (ADNS-6230-001) VCSEL (ADNV-6330). Agilent ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 laser mouse sensor bundles contain laser, safety analysis hazard classification important. manufacturer final system, manufacturer individual pieces, holds responsibility product classification. Since Agilent Technologies, Inc. manufactures above components final product sold consumers, Agilent responsible final classification. This document provided convenience final manufacturer product classification. International Electrotechnical Commission (IEC) governs standardization electrical electronic fields. Optical radiation (eye) safety limits classification levels specified 60825-1, Edition 1.2, 2001-08. This will referred document rest this document. determine safety limits optical output VCSEL (laser) mounted assembly including lens, several factors need known. apparent source size equivalent angular subtense source) ADNB6001, ADNB-6002, ADNB-6011 ADNB6012. wavelength VCSEL. appropriate emission exposure time. Source Angular Subtense Angle Apparent Source Size Measurement source angular subtense spectral range interest specified document (page "For determination retinal thermal hazard limits (400 1400 nm), value angular subtense rectangular linear source determined arithmetic mean angular dimensions source. angular dimension that greater than less than shall limited respectively, prior calculating mean" optical design ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012, emitted beam size collimated with approximately diameter beam (see section "Measuring Beam size"). Since beam collimated, optical equivalent extended source approximately very large (theoretically infinite) distance. angular subtense such source infinitesimally small. Therefore, source considered small source (IEC document, clause 3.79, definition small source). such source, angular subtense taken mrad (milliradians), equivalent source linear extent. derived value parameter 1.0. (IEC document, Table Note page further determination MPE, will used determine which equations use; actual value independent therefore measurements exact apparent source size need performed.
Calculating Accessible Exposure Limits (AEL) Since VCSEL wavelength range specified ADNV-6330 datasheet 865nm, only thermal limits apply this VCSEL, photochemical. determine which equations use, (appropriate exposure time MPE; appropriate emission time AEL) must also known. document (Section 8.4e, page specifically discusses time base these calculations. wavelengths greater than 400nm with Class intention, seconds used exposure time. From Table page document, "Accessible emission limits Class Class laser products", there three different formulas allowed thermal energy when exposure time greater than seconds illumination wavelength between 1050 1.5mrad >1.5 mrad
Since measurement time greater than seconds, therefore less than formula used determine AEL.
10-4C4C7
continue with calculation AEL, need determined. range 1150 (IEC document, page Note equation defines spectral region from 1050nm (IEC document, page note Using minimum therefore worst case value range from VCSEL datasheet, value calculated:
100.002(-700) 100.002(832-700) 1.8365
Substituting into equation above, Accessible Emission Limit (AEL) allowed ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 bundles meet Class This value therefore limit device Class emission must less than equal this value (IEC document, 9.2g, page 33). Compliance this value must finetuned tested Agilent's guidelines manufacturing ADNB-6001 ADNB-6002, ADNB-6011 ADNB-6012, located ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 datasheets. Class another level classification that under acceptable conditions, might allow greater emission limit. This classification does apply ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 design. options given standard (IEC document, section 8.2, page 28). option diverging beam, which does apply. second valid option applies collimated beams where diameter larger than stated aperture stop determined from document, Table page This also does apply given case; therefore Class applicable standard ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012.
-0.25
0.75
Since value defaults seconds, must calculated determine which formula above) used. From document (page Note wavelength range 1400
mrad
10[(-min)/98.5]
mrad mrad mrad
discussed, less than mrad, equation then determines seconds.
Determining Maximum Permissible Exposure (MPE) Maximum Permissible Exposure value critical value that relates injury studies that have been done eye. "Maximum permissible exposure values users below known hazard levels, based best available information from experimental studies. values should used guides control exposures (IEC document, page 49). calculate this guideline ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012, refer Table (IEC document, page 53). with calculating AEL, used wavelength when referring equation table. Exposure time, also necessary again find appropriate equations calculate from Table Given same variable options, equation (labeled below) mrad once again chosen:
Measuring Beam Size ADNS-6120 ADNS-6130-001 lens, ADNS-6230-001 clip ADNV-6330 VCSEL were assembled measured standard distance confirm that accurate value ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 setup. diameter laser this distance significantly less than (fully dilated human eye) then claimed with confidence that Class does apply ADNB-6001, ADNB6002, ADNB-6011 ADNB-6012 optical setup. Below measurement details results. beam diameter measurement, Pulnix Model P-TM7 camera VCSEL fixture were placed line with distance from camera's imaging surface lens surface (see Figures Measurements photos were taken VCSEL beam using Coherent's Beam View Analyzer software.
C4C7
which results 18.37 W.m- Assuming diameter aperture (fully dilated human eye), power through aperture 707µW. Given limited precision (one decimal places) constants formulas, value 707µW essentially same value 716µW determined through Class calculation. This should since product have Class classification, person must subjected exposure exceeding MPE.
Figure BeamView Analyzer setup with camera ADNB-6001 under test
Figure Zoomed photo measurement setup used verify beam diameter (distance =100mm)
Figure Beam Profile representative VCSEL, 100mm from camera ~700uW
Figure plot same representative beam
Data gathered from BeamView Analyzer software (Figures reports effective diameter along with several other characteristics this single VCSEL beam. effective diameter measurement distance specified document measured therefore confidently said that well Class does apply ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 optical setup (IEC document, page 31). Factors contributing overall system Class
Figure Typical Light Output VCSEL (ADNV-6320)
factors that contribute variance light output (LOP) VCSEL (ADNV-6330) must considered; therefore target must then worst-case analysis VCSEL (ADNV-6330) must guard-banded. This analysis must prove that system ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012, under worst-case conditions, defined datasheet, still within Class limit. factors that contribute change ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 discussed below. VCSEL (ADNV-6330) Light output power (LOP) current VCSEL (ADNV-6330) light output (LOP) curve similar typical unit data shown below Figure From this curve apparent that Class limit could exceeded current controlled below necessary limit make safe. Agilent Technologies, Inc. provides manufacturing guideline confirm outgoing product meeting safety limit. This information included ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 datasheet. Following guidelines datasheet critical correctly manufacture Class safe product.
tolerances current control must factored into targeted ensure that ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 will remain within Class limit. Light Output Temperature discussed above section, dependant upon current driving VCSEL (ADNV-6330). Temperature another variable that affects LOP. manufacturing, Agilent performs tests VCSELs (ADNV-6330) sensors (ADNS6000 ADNS-6010), which ensure that change from room temperature operating temperature extremes acceptable. Agilent designed laser system safe within operating temperature range components that make ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012. likely that ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 will exceed maximum Safety limit some units operated outside these temperatures. Since temperature ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 function system (mouse) design, thermal properties material that makeup that system, Agilent recommends that manufacturers perform testing system level determine need special safety circuitry, warnings.
Single Fault Considerations document specifies that products must single fault tolerant. "The above tests shall made under each every reasonably foreseeable single-fault condition; however, faults which result emission radiation excess limited period only, which reasonably foreseeable that human access radiation will occur before product taken service, need considered." (IEC document, section 9.1, page This requirement does apply components, rather final product. Listed below some theoretical single faults ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 bundles. This intended complete list, rather representation foreseeable faults their results.The application schematic found datasheet this product will used reference this discussion. Below list foreseeable faults associated results. results described assume latest released version downloadable programming (SROM) previously been correctly loaded into sensor's memory. Because program held volatile memory, some faults will result loss downloaded programming. micro-controller final product should programmed detect this situation reload SROM program automatically. below references "VCSEL" specifically referring ADNV-6330 part. Broken wire USB/PS2 cable (Power, Ground, Data lines): This fault will increase VCSEL LOP. shorted wire between USB/PS2 cable pins (Power, Ground, Data lines): This fault will increase VCSEL LOP. VDD3 power supply voltage increase greater than 50mV above voltage used during calibration. lifetime mouse bundle shortened VCSEL drive current increase; therefore, Agilent advises manufacturer take necessary steps prevent such voltage increase. Resistive path short circuit between adjacent ADNS-6000 ADNS-6010 sensor pins detailed Table Page
Open short ground short each sensor (pins 1-20). Table Page event: tests sensor (per human body model Method 3015) resulted safe levels. Agilent recommends that manufacturer: follow ESD-safe handling manufacturing processes warn end-users that mouse opened tampered with provide safety precautions such that mouse opened, laser current drive disabled. design mouse case board prevent exposure above RBIN XY_LASER pins. Defective pass transistor: (XY_LASER current continues limit current correct value). Noise event clock corrupts internal memory values: event such this concept affect laser current. current adjustment settings kept memory locations different forms. each frame, sensor checks corruption reduces minimum laser power found therefore minimizes "foreseeable" chance that this event would result unsafe levels. Fault detection relies proper operation ADNS-6000 ADNS-6010 sensors. Proper operation should confirmed periodically reading Product register inverse documented ADNS-6000 ADNS-6010 datasheets. Once proper operation assured, Fault LP_Valid Motion register should read detect fault condition. Conclusion Analysis ADNB-6001, ADNB-6002, ADNB-6011 ADNB-6012 safety 60825-1, Edition 1.2, 2001-08 shows that given proper current control VCSEL detailed adherence manufacture instructions sensor datasheet, this product ability meet product classification standards with rating Class
Table
Names MISO MISO SCLK SCLK MOSI MOSI RESET Explanation Will affect VCSEL power since these serial port digital pins Will affect VCSEL power since these serial port digital pins Will affect VCSEL power since these serial port digital pins Will affect VCSEL power since these serial port digital pins This fault reset ADNS-6000 sensor. While RESET active (high state), laser turned off. After RESET brought sensor will drive laser minimum programmable drive current. both cases VCSEL power only decrease remain same pre-fault level. Same result pins sensor reset. into power down mode (NPD held low), laser turned off. Upon removal fault exit power down mode, laser will return previously programmed power level. Will affect VCSEL power since these clock serial port pins Will affect VCSEL power since these clock ground pins Will affect VCSEL power since these clock ground pins. This event cause collapse internal analog supply, which would result reduction VCSEL output comparator RBIN circuit detects short circuit between these pins will turn laser. Resistive paths increase laser current. Agilent recommends mouse manufacturer include features design counter this result. features include adding guard trace devoid solder mask surrounding entire Rbin node connected VDD3. With this design, resistive leakage between RBIN guard trace will reduce laser power. Conformal coating these pins, traces, Rbin resistor alternative. sensor will latch state with zero laser current. sensor detects short circuits between XY_LASER ground. When detected, external pass transistor turned off. short resistive path would either: waste supply current leave laser power unaffected collapse supply voltage then turn reduce laser power Same pins Same pins Same pins short resistive path failure here does alter VCSEL power.
RESET
OSC-OUT GUARD OSC-OUT GUARD OSC-IN REFC REFB REFB RBIN
RBIN XY_LASER XY_LASER VDD3
VDD3 VDD3 VDD3 LASER_NEN
Table
NAME MISO SCLK MOSI RESET OSC_OUT GUARD OSC_IN REFC
OPEN effect laser effect laser effect laser effect laser effect laser Laser remains safe power effect laser effect laser effect laser effect laser cause oscillation internal supply, Laser remains safe power effect laser Laser power drops drive circuit programming current becomes Laser power drops current flow) effect laser other pins exist effect laser other pins exist effect laser other pins exist effect laser other pins exist effect laser other pins exist Laser turns greatly reduced power since pass transistor driven
SHORT effect laser effect laser effect laser effect laser effect laser Laser always effect laser effect laser collapse, laser power remains safe effect laser effect laser
SHORT effect laser effect laser effect laser effect laser effect laser Laser remains safe power effect laser effect laser effect laser effect laser collapse, laser power remains safe effect laser Laser shut internal detection circuit Laser turned LASER_NEN output internal detection circuit effect laser collapse, laser power remains safe effect laser collapse, laser power remains safe effect laser effect laser XY_LASER current source remains correct
REFB RBIN
collapse, laser power remains safe Laser power drops drive circuit programming current reverses Laser power drops (both ends tied VDD) collapse, laser power remains safe effect laser collapse, laser power remains safe effect laser collapse, laser power remains safe Laser turns since pass transistor
XY_LASER
VDD3 VDD3 LASER_NEN
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Application Note 5088 Introduction safety calculations presented

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