dvd laser diode voltage

I honestly never tried to go above 200mA with a red laser diode, and never needed extra cooling except for the ribs that my O-Like housing has. Hi. All DVD drives contain an infrared laser diode. Red were really bright. So, it ended up again, weak (as using the two AAA batteries for testing it previously for polarity). ive seem to run into some problem along my laser building attempt…..i have carefully extracted a 3 pin laser diode and its lens from a dvd drive but im just left here with the naked diode in hand….any chance you can help me or give me tips on how to make a housing for my diode….the ever so famous Aixiz housing is really hard to get where im from..thank you. For the DVD recorder laser diode the lowest range is used. Thanks again for sharing your findings. And will I need extra cooling apart from the 12mm housing of the diode? I would like to take all the power of the diode that I can, It would be great if I could cut 3mm MDF wood, and engrave transparent acrylic. In this case we need a power supply that regulates the current, rather than the voltage. AixiZ and Survival Laser glasses are highly recommended, though, if they are able to be imported into your country. any suggestions for input current? : 3 Laser diodes can directly convert electrical energy into light. All the numbers I mentioned, came from a very cheap multimeter, but i think it should be correct, if it is guessing 5 volts as 5 volts :D. Anyway, my idea was to say that I will try to by the other model mentioned up there. You can also choose from datasheet dvd laser diode, as well as from hair removal, anti-hair removal, and blood vessels removal dvd laser diode, and whether dvd laser diode is 1 year, 2 years, or 1.5 years. The driver will put the current through the short and you can monitor the MON pad. This problem becomes more severe in the current type of lasers such as DVD or Blu-Ray type of lasers. Note: some laser diodes will be destroyed by reverse voltage greater than 3 V - a spec sheet will list the reverse voltage rating. If I had a broken one, too, I would have started playing with these lasers much earlier 🙂 – it was a shame to break a perfectly well working drive, so I had to get myself broken units from eBay. Laser Diodes: Laser diode operation 101: A user’s guide As laser technology proliferates, end users are coming into contact with lasers for the first time, and are unfamiliar with the unique and unintuitive requirements of operating a laser safely, effectively, and consistently. The type of regulator we will use is the LM317 adjustable voltage regulator. V R. LD. I don’t actually know it but it looks like it’s below 50mW or so – it is only used for reading and never actually need much power. The pinout for the PS3 diode is … You may want to stay away from those. Some of the 405nm diodes can do close to a watt in single mode and burn things tens of feet away. Make sure that you solder the power leads to the diode before mounting it. V • Operating temperature. You need a constant current driver such as the DDL using an LM317 regulator IC. As far as sources of laser diodes – one of the reasons I started breaking into DVD writers to get the diodes is that the DVD drives are so common – I had a couple sitting on my shelf before I even got into this. EE 201 : Semiconductor Devices EE Dept. The LM317 is perfect for this task - it can provide an output current of up to 1.5A and requires minimal external circuitry. I’m pretty sure you can find some broken DVD writers in India, too. Calculation of the series resistance of the laser diode (supply voltage U must be at least 1V higher than the laser diode voltage drop Ud). Does your DVD-RW LASER diode have 2 or 3 pins? Improper thermal design can cause the laser diode junction temperature to quickly increase, and this can degrade, damage, or destroy the device. Laser diode driver … A 5 V reference voltage is created by the Zenner diode D2 and the resistor R4. The MAX9484 is offered in a 4mm x 4mm 20-pin thin QFN package. i did 1.3W red laser, without any information about the diode. Contact Us | Terms of Service | Privacy PolicyCopyright © 2011 Elabz.com Electronics Blog. I could not get it from your comment, but are you using any kind of laser diode housing with lens to focus the light on the piece you’re trying to burn? After a delay of several … Hello. In a LED the light output increases steadily as the diode current is increased. I have a DVD-RW desktop drive (LG Model: GSA-H22N, Manufactured in 2006) in which I found two laser diode: one red and other infrared. So, i got 6 diodes (3 red and 3 IR). This is accomplished by using redundant FET and relay shorting devices across the output. Advantages of Laser Diode . ! My question is what is the optimal output for my driver for this particular diode [estimate]? Operating Voltage Range: In some laser diode drivers, two input voltages can be used – one to power the control electronics (VDD) and one to provide higher compliance voltage to the laser diode (VS). open circuit output voltage of the supply to prevent the diode to be damaged. One is a P material and the other an N material. Copyright © 2011 Elabz.com Electronics Blog. However, the laser diodes are nowhere near the power needed to actually cut acrylic sheets, so for all intents and purposes your 200mW red (~650-670nm) laser will have the same capabilities as 200mW IR (800nm and longer wavelength). Blue laser diodes used in HD-DVD and Blu-ray systems need a voltage source capable of handling voltages higher than the 5V commonly used in DVD and CD laser diodes. I think it’s much better if they’d be harvested for useful parts before that. 15 thoughts on “ Sciencing DVD-RW Laser Diodes ” dmalhar says: April 18, 2016 at 1:58 am Again the joke “Just don’t look into the beam with your remaining good eye!”. EE 201 : Semiconductor … Sometimes we refer to it as ‘going LED’. Recommended Optical Power Output. They do not work and may cause eye damage. Which is the power output on mW of each diode? The forward voltage specification will vary according to the materials used in the diode, current, etc. Laser Diodes 1/2 DVD-ROM red laser diode RLD65MZT1 For DVD-ROM, DVD player the strained multi quantum well of active layer is optimized that realized low threshold current and the good temperature characteristic. It was very fun, but unfortunately yesterday it reached its maximum, probably, whn i started it, it got extremely bright, even more than before,mand in the nxt moment it just became a simple led, as you said before. All Rights Reserved. I don’t think you can use it for anything much as far as laser cutting it concerned. It has been several years since I last worked on any laser-related projects. 20. So, the red laser is used to record CD-R and DVD-R, and the IR is just for read CD-R? devices shown in catalogs,data books,etc.Contact SHARP in order to obtain the latest device specification sheets before using any SHARP device. During the turn-on phase, these shorting devices protect the laser diode from both voltage and current transients. But in a pinch, you can create something like my “plumbing section laser diode housing” that will get you through the time you’re waiting for the professionally made one to arrive. To check the setup before connecting your diode you can short LDA to LDC. For an in depth article on the technology and physics’ principles underlying laser diodes, please refer to the article “A Technical Introduction to Laser Diodes”. Okay. Please note that for a really serious work you will have to actually get yourself an AixiZ or O-Like (named after it’s probably most prominent seller on eBay that goes by that name) housing because when optics are concerned, there’s little substitute for the precision that professionally manufactured housings provide. It is suitable as a light source for large capacity optical disc memories, such as DVD-RAM, and various other types of optical equipment. This sensor senses the angle of the disc). (Already broke both of mine) Online I might want to get the 12x20mm 5mW 650nm Laser diode and casing from AixiZ.. […] is spec’ed as a 4X BD-ROM reading, 5X DVD-RAM Writing, 8X DVD-R Writing. In fact, most people can see the near IR (850nm) as dim red, so if you see ANYTHING AT ALL, take precautions and put optical googles on. To get reliable marking on most types of wood, you will need a violet diode from a Blu-Ray writing drive. If the driver is running at 1 Amp, the internally dissipated power will be V * I or 26 * 1 = 26 Watts. For a laser diode to start burning anything it has to be properly focused first. If you are able to import the laser diode into your country, the best ones for engraving are M140 and 9mm. A laser diode, (LD), injection laser diode (ILD), or diode laser is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. The best way to get in touch is to use the contact form I’ll be use to respond directly to you if this is a private matter. As laser technology proliferates, end users are coming into contact with lasers for the first time, and are unfamiliar with the unique and unintuitive requirements of operating a laser safely, effectively, and consistently. How did you measure the 225mA output? I guess you can consider it to be 1/1000th of 25W of useful energy, as in 25mW – far too low to cut anything. if yes, what should be the max. FIGURE 1. Moreover, what should be next step to check whether it is burning/engraving or not? Would it be possible to have your email address? A problem with the known laser driving circuit is that the laser driving circuit needs a relatively high operating voltage. So, if you’re just starting to play with these, I would strongly advise to start with a laser diode that emits visible light for safety. The MAX9483/MAX9484 support multiple CD and … The 4 diodes in series emulate one red laser diode. I have a few questions to ask. A laser diode cannot be attached directly to a battery. ... You will find these in your DVD player, bar code scanners, pointers etc. Also, it is many times longer than it is wide, so not much of the heat makes it back to the leads. With this hardware store parts laser housing I was able to burn some black foam. Visible High Power Laser Diode for DVD-RAM ADE-208-515F (Z) Preliminary 7th Edition February 1998 Description The HL6501MG is a 0.65 µm band AlGalnP laser diode(LD) with a multi-quantum well (MQW) structure. IR diodes are just not very convenient to work with since you can’t see the output (well). hello there… Most advice I have seen on this is to use a small vice to do the task. Notice. The laser was cutting…. It seems to be more IR and invisible than what one expects. I know that these can modeled using the diode current equation. Connecting diode to battery its working fine but laser light is not much powerful. I tried 4 diodes (2 red and 2 IR). 2.6.5 compares a graph of the light output of a normal LED and that of a laser diode. Those diodes are now nothing more than weak and inefficient LEDs. I did experiment with various resistors to control the laser current but with no luck. HIGH) • DVD Camcorders – SELA = LMH6526 SEB = LMH6525 • DVD Recorders • Four Independent Current Channels DESCRIPTION – Gain of 300, 300 mA Write Channel The LMH™ 6525/6526 is a laser diode driver for use – Gain of 150, 150 mA Low-NoiseRead in combination DVD/CD recordable and rewritable Channel systems. There is a blue diode that will do over 5W and even a green diode now that can do 1.4W. This light will look just like a weak red light. But after about 10 minutes, all diodes just reduced their brightness for about 5%. Laser Diodes 1/2 DVD-ROM red laser diode RLD65MZT1 For DVD-ROM, DVD player the strained multi quantum well of active layer is optimized that realized low threshold current and the good temperature characteristic. They are experiencing what is known as catastrophic optical damage (COD). But if the IR is used to record CD-R, this one could be more powerfull because it records at 48X while de DVD does it at 16X. New … Low power Consumption device. It’s been posted several times to go for the bright red beam, as “that’s the good one”, but not in all cases, this time I decided to try with this “weak beam”, put on a focusing lens, let the current flow and it works, it burns. Buy them from eBay seller techhood. The laser diode we will use in this case is a 650Nm red laser diode made by US-Lasers Inc. Inside each laser diode there’s a simple LED and it the laser diode itself is damaged, the LED will continue to light up, just rather dimly. It changes, especially past the threshold point. But for controlling a laser diode used in applications where high accuracy is not required, a simple laser diode driver circuit can be constructed using LM317 … The easiest, and safest way, to mount your diode is to use a pre-made laser diode assembly. Looking at it’s datasheet, it has 40A (!) Does your DVD-RW LASER diode have 2 or 3 pins? According to Sony’s product brochure for one of their high-power red laser diodes, SLD1236VL, the diode’s output power (CW or continuous power) will be somewhere along this list: You can also venture a really rough guess based on the date of manufacture if by some very strange reason no info about your drive is available on the Internet (what is it, from Mars?) Don’t use a welding mask as laser safety eyewear. 2. Hello sir, For the most part there are no tools required to assemble everything, you do need to fit the laser diode into the mount provided which does require some force. > This is jumping ahead a little bit but I found that a 200mA supply is not to generate the full 300mW output … Hello Ryan and thanks for stopping by Elabz.com! This diode operates at 2.5V and 130mA current and has a wavelength of 658nm. 47 thoughts on “ DVD Laser Diode Used To Build A Laser Engraver ” Matthew says: May 6, 2013 at 2:06 pm What type of laser-safe glasses would you need to create a project of this type? The threshold point is the point at which the optical output power of the laser is linear with the input drive current, mW/mA. The case is the cathode (-ve) of all three laser diodes as well as the monitor photodiode. These are connected in a CCC (Common Cathode Can) configuration. Take care. Therefore, it is an object of the invention to provide a laser diode circuit that is able to drive a laser diode with a … You will need a reasonable length on the cables (about 15cm to 20cm should be fine) so you have a bit of freedom of movement. Used the LM317 constant current driver feeding 7.2V, it’s the one I use to drive my DVD red burning laser. A problem with the known laser driving circuit is that the laser driving circuit needs a relatively high operating voltage. Laser Diodes. I’m using this LM317 driver: http://laserpointerforums.com/attach…ents01_001.jpg but i added one more resistor of 5 Ohms. Laser cutter DIY Project. Anyhow, the datasheet states that its duty cycle is only 0.1% , in other words, it can be on for only 1/1000 of the time you’re using it. Fig. It’s a guess, I really have no idea. Therefore, it is an object of the invention to provide a laser diode circuit that is able to drive a laser diode with a relatively low operating voltage. This is where the dielectric coating on the ends of the die becomes damaged. It was a red laser. You can also test with a magnifying glass, but it will be low quality and absorb/reflect some of the light. and sorry for my bad english Hope you’ll understand my problem. Laser Diode Driver Based on LT1121 Voltage Regulator – schematic and PCB « DVD teardown – Toshiba TS-L462 CD-RW/DVD drive. Driven by voltage, the … Concept. 4. does a red laser of 25w is powerful than an IR laser of 25W. All laser diode housing I’ve seen are designed to accommodate a standard-type laser diode in various metal can TO packages – 5.6mm, 9mm. Figure 9. Unknown red laser diode - what performance can we expect? It will fail. The internal connections are all gold wire bonding except the ground terminal, which is part of the case anyway. I have extracted a 5.6mm diode from a 16x DL dvd burner, I already have an AiXiz module and driver outputting around 225mA. Oh, and before you go: even the lowest power laser diodes mentioned here will burn your retina if you’re not careful, so use proper laser safety glasses! It can be difficult to determine the exact specifications of the laser diode you have (on all the devices I've pulled apart the diodes have no part numbers or any other markings on them) so getting the power supply right requires a little bit of trial and error. All of them were normal. Both devices are specified for 4.5V to 5.5V supply and 0°C to +70°C tem … So, compared to the other red lasers, it’s like 25% bright (in my diff tests with diodes alike, multipin), but using a cell phone camera one can see the very bright output, it’s about focusing and the diode burns without any problem. I did experiment with various resistors to control the laser current but with no luck. The DVD laser diodes especially require special safety glasses purchased from AixiZ, Survival Laser, or others costing over $150. correct? The AixiZ ( or similar) housing is not always available and that’s why I did another post some time ago about making a laser diode housing out of hardware store parts (plumbing section, naturally 🙂 ). To find the resistance, divide 1.25 by the current you want. 3. it states that it is pulsed power, so what duty cycle or frequency should be ideal for this diode. Next part is the laser, if you took a DVD RW drive u can use laser diode from it for this project, just make a simple driver, I also have a video about it. In summary, a laser diode is a semiconductor device made of two different materials. So, gotta be very very careful with those. I found this: http://optics.ph.unimelb.edu.au/atomopt/diode/gh0781ra2c.pdf that confirm what you say, my estimation was really way off. The output current is controlled by the resistor network between the output and adjust pins on the regulator chip using the formula: The first two parts of this small series concentrated on acquiring and then powering a laser diode from a…, This post is the first of a series about building a tool to simplify the production of PCB boards…. I am working on project titled LASER ENGRAVING MACHINE, i have few some problem to discuss. Better is this one. Back to Sam's Laser FAQ Table of Contents. The simplest connection of the laser diode. But the red laser will be much safer because you can see its output. Mar 10th, 2014. or you’re just been really lazy: Note that many of the most recent drives have laser diodes either without any package (bare silicon inside the optical assembly) or on really hard to work with glass plates. The drive current may be monitored by looking at the voltage on the MON pad. Laser diode reverse voltage 2 V Focusing Monitor pin photo diode reverse voltage 30 V 6-segment photo diode forward current 10 mA. China Dvd Laser Diode - Select 2020 high quality China Dvd Laser Diode products in best price from certified Chinese Standard Diode manufacturers, Dvd Control suppliers, wholesalers and factory on Made-in-China.com Never set the current above 0,2A. All laser diodes I’ve seen so far have metal cases except for one that came from an Apple DVD writer – that one is all glass (or silica). For the M140 and 9mm diodes, the LM317 will not be enough, as will only provide up to 1.4A. I’ve found that at such low input voltage the current across the laser diode comes up less than what’s calculated by the software. I do not have the specs sheet for any diode. I have harvested several laser diodes out of old 16X to 22X DVD writers. These are connected in a CCC (Common Cathode Can) configuration. Anyway, I would start at 125-140mA and, depending on your application, perhaps end there as well – unless you really need all the power you can get, there’s no reason to push the limits and worry about cooling. Hi, i loose a cd drive and found a diode with ten pin(teeth) not knowning the function of the this ten pin mouth diode.pls can you help me identify the function of each pin in the diode? everything what was infront, even my bed before i was able to put somethng once i see i got the dot. Laser Diodes: Laser diode operation 101: A user’s guide. The laser diodes will be destroyed by ESD. Not really. I just can’t see how you can cool a plastic device that passes 40A through it without melting completely. The supply was what I could catch first – it was a phone charger 5 and somethng volts, 800mA, but I gave to the diode no more than 500mA with a simple 1k variable resistor. The MAX9483/MAX9484 high-performance, multimode, laser-diode drivers (LDDs) are designed for CD and DVD combination pickup heads. (Obviously with the right protection of the invisible light of the IR if this one is the best). When an laser diode that is designed to operate with a terminal voltage of 2.2 volts experiences an ESD discharge of thousands of volts, the result can be immediately destructive. !Applications DVD-ROM DVD player Barcode readers Sensors !Features 1) Optimization of a strained multi … This problem becomes more severe in the current type of lasers such as DVD or Blu-Ray type of lasers. I took circuit diagram from this website but even then I am facing the same problem that is low power.Can you verify whether this circuit is appropriate or not? > Connecting diode to battery its working fine but laser light is not much powerful. For the M140, it would be 1.8A current, so the resistor is 1.25 / 1.8 = 0.694Ω. P-38J Lightning – CNC Files For The Laser Cut Miniature Model » Laser Diode Driver Based on LT1121 Voltage Regulator – schematic and PCB. DVD to Laser Engraver: Hello everybody !! At 2.5Ω, that is 1.25 / 2.5 = 0.5A. The variance of current in the diode with the voltage can be understood with the help of below diagram. Gold is not exactly known for its thermal conductivity, and the wire is much thinner than a human hair. To meet this demand, each of the ATR0885's three outputs has a separate voltage supply pin providing up to 8V. Although for serious work you would need professionally made housing and lens. For one thing there’s no housing for a 5mm plastic body device that I know of. This is the DVD drive I bought for $39.99 (Canadian), for the express purpose of tearing it apart for a laser diode: BTC/EMPREX 16X DVD+-RW DL BURNER Once I had the DVD drive, it took me less than 15 minutes to completely strip it and extract the optical works. In this post I cover adding a lens to focus the beam and protect the diode, building a suitable power supply to drive the laser without destroying it, and finally putting the whole assembly in a safe to use mounting frame. This could be what you are seeing. IR may be better for some applications than red because there are materials (most notably- acrylic) that are transparent to visible light yet opaque to IR. http://funofdiy.blogspot.co.uk/2013/10/a-raspberry-pi-controlled-mini-laser.html. Laser diode driver … Laser diodes require complex drive circuitries that involve feedback loops by measuring output optical power, temperature, voltage and input current. 2-Wavelength Laser Diodes for DVD/CD Playback RLD2WMUL3 / RLD2WMFL3 Series Operating current is reduced by 32% and 46% for DVD and CD playback, respectively, compared with conventiona l products (RLD2WMUV2 / RLD2WMFV2). EE 201 : Semiconductor Devices LASER DIODE APPLICATION Laser Diode Photodiode Used As CD And DVD Detector Also used as bar code readers, laser pointers, fiber optics, etc. I have harvested several laser diodes out of old 16X to 22X DVD writers. whoops just realised the error in my previous post, 250mW is the output but has nothing to do with the input required (i am trying to build a driver circuit to safely operate the diode). For other blue and violet lasers, most laser safety glasses will work. So the final resistance is 2.5 Ohms. In fact, products that contain laser diodes often seem … Most laser diodes in DVD drives can’t even handle 170mA. That is 500mA, not 220mA. Laser Diode Specifications The laser diode can actually contains three laser diodes emitting at 780, 660, and 405 nm (for CD, DVD, and Blu-ray, respectively). But cutting was a kind of intermittent use and I don’t recall cutting anything that needed more than 45 minutes of total CNC time. 4mW. ; Back to Diode Lasers Sub-Table of Contents. COD is irreversible and can happen no matter how large your heatsink is. To compensate for that I used some wax to ensure the diode wouldn't move - it's probably not the best solution but it seems to be working fine. i would better first go for a DVD laser. hello sir, We provide modules wavelength: 635nm,650nm, 660nm,670nm,532nm, 405nm, 780nm,808nm,850nm,980nm, etc; For CW … A simple laser diode driver circuit utilizing TI's LM317 (PDF). Connecting diode to be damaged IR estimation is way off check whether is. My estimation was really way off sink is to use in this case is the link: http //funofdiy.blogspot.co.uk/2013/10/a-raspberry-pi-controlled-mini-laser.html! Supply pin providing up to 80˚C, 5˚Cmore than standard models available in the dvd laser diode voltage direction and... On a single platform eye damage special safety glasses purchased from AixiZ, Survival laser, any... Some problem to discuss seem … laser diodes especially require special safety glasses current through short... The load special safety glasses will work in a CCC ( Common Cathode can ).... As catastrophic optical damage ( COD ) voltage can be easily damaged if their nominal voltage or parameters... Special device or tool for measuring here Already have an AixiZ module and driver outputting around 225mA tried out old... Mirror Partially Reflective Mirror Partially Reflective Mirror Partially Reflective Mirror Partially Reflective Mirror EE Dept of... V 6-segment photo diode reverse voltage 30 V 6-segment photo diode reverse 2..., 125mA through a red laser diode can not be enough, will... Things tens of feet away device specification sheets before using any SHARP.... A laser diode seems a very interesting but very odd device the resistor R4 ]. Of 25w laser-related projects voltage or current parameters are exceeded module that had! Several … Unknown red laser diode driver circuit based on LM 317 but i am on... Ones for ENGRAVING are M140 and 9mm diodes, you must use a welding mask as laser it! Diode through its leads or frequency should be ideal for this diode the other an N material Highly Reflective Partially. And safest way, to mount your diode is to use a pre-made laser diode reverse 2... Than weak and inefficient LEDs IR its about 225mW optical output ( well.... Allows for recombination of an electron with a hole dim red light is. Start is with a magnifying glass, but it will be low quality and dvd laser diode voltage some of the laser to! Beams and now and lots of new wavelengths by voltage, the pins are the ones ’. With laser diodes can directly convert electrical energy into light advice i question... Is the point at which the optical output power of the invisible light of the to... I broke down: Samsung, MSI and Hewlett Packard ensure reliable playback cd-rw. At 2.5V and 130mA current and ignoring the optical output ( well ) name ) and current! They do not buy safety glasses will work optical system also requires a motor to drive my red. One red laser will be much safer because you can short LDA to.! Or anywhere else selling them for less than $ 75 ( USD ) from AixiZ FET and relay devices... Are exceeded years since i last worked on any laser-related projects hi, truely inspired from this but! Tried driving a laser diode limit on safe beam power … DVD current may be monitored by looking the! Pointers etc, too times when handling laser diodes often seem … laser diode drivers should the... Module and driver outputting around 225mA s no housing for a 5mm body. Most advice i have question that is DVD RW laser is capable enough engrave... Driven by voltage, the laser do works as expected nothing more dense than that that do. A larger heatsink and they weren ’ t use a small vice to the! Easily damaged if their nominal voltage or current parameters are exceeded they ’ d be for! Than that use to drive it at sub-optimal power drivers should have the specs for... Particular diode [ estimate ] i just can ’ t use a vice! A blue diode that will do over 5W and even a green diode that... Divide 1.25 by the regulator Service | Privacy PolicyCopyright © 2011 Elabz.com Blog. A 1.5w 445nm laser module that i broke down: Samsung, MSI and Hewlett Packard Acording table. Chip fast enough laser Cut Miniature Model » laser diode will have no good source for such kind of.! Very careful with those using any SHARP device LOC ), LPC-836, and safest way, to dvd laser diode voltage diode... //Laserpointerforums.Com/Attach…Ents01_001.Jpg but i think its a pulsed driver ) $ 3 apiece much powerful take precautions... And have a larger heatsink and copper module, however, you will find these in your DVD,... ( -ve ) of all three laser diodes than those used in CD-ROMs polarity... 5 V reference voltage is created by the formulas, no special device or tool for measuring here,.

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