THORLABS LDM21 User manual

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LDM21(/M)
5.6mm/9mm
LaserDiodeMount
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UserGuide
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TableofContents
Chapter1  Safety...................................................................1 
Chapter2  Description...........................................................2 
Chapter3  Setup....................................................................3 
3.6.1  TheoreticalResistanceValues............................................10 
Chapter4  Operation...........................................................12 
Chapter5  Troubleshooting.................................................14 
Chapter6  Specifications.....................................................16 
Chapter7  MechanicalDrawing...........................................17 
Chapter8  WarrantyandRMAInformation.........................18 
Chapter9  ThorlabsWorldwideContacts............................19 

5.6mm/9mmLaserDiodeMount Chapter1:Safety
Rev.L,March23,2023  Page1
Chapter1 Safety
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Warning
This unit must not be operated in explosive
environments.
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Warning
Avoidexposure–laserradiationemittedfromapertures
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5.6mm/9mmLaserDiodeMount Chapter2:Description
Page2  TTN013394‐D02
Chapter2 Description
TheLDM21(/M)isatemperature‐controlled laser diode mount. When
usedwithThorlabsLDCSeriesLaserControllersandTEDSeriesTEC
Controllers, a laser diode can be operated with precise temperature
controlforwavelengthandpowerstability.Afourpinsocketacceptsall
9mmand5.6mmlaserdiodes.Easytousepolarityswitchesallowthe
lasermounttobeconfiguredforallpossiblelaserpinassignments.
TheLDM21(/M)wasdesignedwithfeaturesthatallowittobeeasily
incorporatedintocomplexsystems.ThefrontoftheLDM21(/M)hasan
SM1(1.035"‐40)threadtoacceptawide variety of Thorlabs SM11.0"
opticsmountsandaccessories.Alsostandardwiththemountare4‐40
tappedholeson 30mmcentersformountinganynumberofThorlabs
cageassemblyproducts.Therearealsofour8‐32(M4x0.7)tappedholes
toallowtheunittobepostmounted.
TheLDM21(/M)usesathermo‐electriccooler(TEC)topreciselyregulate
the operating temperature of a laser diode. Temperature sensingis
accomplished using an integrated thermistor and AD592 solid state
temperaturesensor.TheThorlabsTED200Csupportsthesesensors.
NOTE:TheLDM21(/M)isintendedforlaserdiodesrequiringlowinput
power and operating across a limited temperature range.  Its primary
functionis tomaintainthelaserdiode casetemperatureataconstant
temperature to within 0.2 °C, ideally at 25 °C in a typical laboratory
ambientenvironment(20to30°C).PleaserefertotheSafeOperating
AreachartinthismanualtoensurethattheLDM21(/M)isusedwithinits
capabilities.
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Figure1 InsideViewofLDM21andIncludedComponents

5.6mm/9mmLaserDiodeMount Chapter3:Setup
Rev.L,March23,2023  Page3
Chapter3 Setup
LaserInstallation
1. Unpackthelasermountandremovethefour2‐56socket‐head
screwsfromthefrontcoverusinga5/64"hexdriver(provided).
2. Remove the two Phillips head 2‐56 screws from the laser‐
mountingflangeandremovetheflange.
3. Determine the laser pin configuration from the laser diode
manufacturer’sdatasheetsandsettheLD(LaserDiode)andPD
(Photodiode)switcheslocatedontheinsideoftheunitaccording
toFigure2.
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Figure2 PolaritySwitchSettings
LD
Style A
Style B
Style C
Style D
AG CG
PD
CG AG
LD
AG CG
PD
CG AG
LD
AG CG
PD
CG AG
LD
AG CG
PD
CG AG
Case
LD PD
LD PD
LD PD
LD PD
Case
Case
Case

5.6mm/9mmLaserDiodeMount Chapter3:Setup
Page4  TTN013394‐D02
 The four sockets comprising the laser diode connector are
through‐hole type sockets with a blind clearance of 0.48”
(1.22cm)measuredfromthefrontfaceofthecoppercoldplate.
Itisnotnecessarytotrimthelaserdiodeleadspriortomounting
intothisconnectorunlesstheyarelongerthan0.48”(1.22cm).
 Thelaserconnectorislocatedcloseenoughtothefrontfaceof
thecoppercoldplatetoalloweasyinstallationofshort‐leaded
lasers. The clearance area around the LD and PD sockets is
sufficienttopreventthepinsfromcontactingthecoldplate.
 Mostlaserdiodesarethreepinswiththecasetiedtooneofthe
laserpinsandalsotooneofthephotodiodepins.Theotherlaser
and photodiode pins will be isolated from the case. The
LDM21(/M) was designed to operate the laser case at ground
potential,thereforethiscommonpinwillbeinsertedintoeither
the12o’clockorthe6o’clockpositionofthelaserconnector.
Locatetheisolatedlaserpinandinsertitinthe3o’clockposition.
Theisolatedphotodiodeshouldnowbeinthe9o’clockposition.
Refer to Fig. 3. (Orient the mount with the PD polarity switch
abovetheLDsocket).
 TheLDM21(/M)MountisalsocompatiblewithstyleEandstyle
Hlaserdiodes,whichdonothaveaphotodiode;theyhaveonly
alaserdiodeandagroundpin.Theycanthereforebesetupthe
same as style A (LD Anode Ground) or style B (LD Cathode
Ground)respectively.
 Replace the laser mounting flange and the cover. Install both
screwsthroughthemountingflangeandlooselyintothemount.
Carefullytighteneachscrewalittlebitatatimeuntiltheflange
isjustsnug.Donotover‐tighteneitherscrew‐theflangeshould
sitslightlyabovethecoldplate.Reinstallthecoverusingthefour
2‐56capheadscrewsprovided.

5.6mm/9mmLaserDiodeMount Chapter3:Setup
Rev.L,March23,2023  Page5
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Figure3 LDandPDOrientation
5.6mmAdapter
Bydefault,theLDM21(/M)isdesignedtobeusedwithstandard9mm
laserdiode packages.Themountcanbeusedwithastandard 5.6mm
using the included adapter, which can be found in the small brown
envelopemarked“Accessories”ontheoutside.Includedinthisenvelope
isthe9mmmountingplateandtheimperialtometricmountingadapter.
4‐PinLaserDiodes
TheLDM21(/M)alsosupports4‐pinlaserdiodes.Insertthelaserintothe
4‐pinsocketandnotewhichlaserpinisinthe3o’clockposition(laser
anodeorcathode). Also note whichphotodiode pin is inthe9 o’clock
position(anodeorcathode).Themountwilltiethelaserandphotodiode
pinslocatedat12o’clockand6o’clocktogetherandalsotoground.By
notingwhichpolaritypinsareinsertedintothesocket,youcanconvert
the4‐pinlayouttooneofthe3‐pinlayoutsinFigure2onpage3.Setthe
LDandPDpolarityswitchesaccordingly.
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G
G
LDPD

5.6mm/9mmLaserDiodeMount Chapter3:Setup
Page6  TTN013394‐D02
LaserControllerConnections
UsingtheThorlabsLDC/ITCSeriesLaserControllers:
 TheLDM21(/M)iscompatiblewithallThorlabsLDCLD
controllersandITCseriescombinationcontrollers(LDandTEC).
Appropriate cables with DB9 connectors are included with
Thorlabs controllers and ensure that the controllers cannot be
connectedincorrectly.Additionally,thesecontrollershavebuilt‐
inprotectioncircuitrythatprotectsthelaserwhennotinuse.
 ThenomenclaturefortheLaserDiodepolarityswitchonthe
LDC/ITC driver and the LDM21(/M) are consistent with each
other.Forexample,ifthelaserpolarityonthedriverissetto
“AG” (anode grounded), then the LD polarity switch on the
LDM21(/M)shouldalsobesettoAG,andsoforth.
 ThenomenclatureforthePhotoDiodepolarityswitchonthe
LDC4000SeriesBenchtopControllers,PRO8LaserDiodeCurrent
ControlModules,andITCseriesdriversandtheLDM21(/M)isas
follows:ThephotodiodepolarityswitchontheLDM21(/M)must
alwaysbesetto“CG”.Thephotodiodepolarityshouldbesetwith
theinternalLasercontrollerswitchonly.Formoreinformation
onhowtosetPolaritysettingsontheLasercontroller,please
refertotheappropriateLaserControllermanual.
Usingathird‐partylasercontroller:
 Whenusingathird‐partycontroller,acustomcablewillhaveto
bemadetoproperlyinterfacetothelasermount.Pleasereferto
thetableonthenextpageforlaserconnections:
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