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- เผยแพร่เมื่อ 2 มิ.ย. 2024
- Thorlabs demonstrates two techniques for aligning a laser beam to travel parallel with the optical table. The first technique assumes the tip and tilt of the laser's pointing angle can be adjusted and uses a ruler to level the beam and direct it along a row of holes in the table. The second technique assumes the angle of the input laser beam is fixed. Two turning mirrors and two irises are used to level the beam and direct it along an orthogonal row of holes in the table.
0:00 - Introduction
1:25 - Adapter Used to Install Laser in Kinematic Mount
2:05 - Adjusting the Mount to Correct Pointing Angle
4:09 - Beam Walk Demonstration Using Mirrors & Irises
Components used in this demonstration include:
- PL202 Collimated Laser Module: www.thorlabs.com/newgrouppage...
- KM100 Kinematic Mounts: www.thorlabs.com/newgrouppage...
- AD11NT Adapter: www.thorlabs.com/newgrouppage...
- BHM1 Ruler: www.thorlabs.com/thorproduct....
- PF10-03-P01 Mirrors: www.thorlabs.com/newgrouppage...
- IDA25 Irises: www.thorlabs.com/newgrouppage...
- Ø1/2" Post Holders: www.thorlabs.com/newgrouppage...
- BA2 Base: www.thorlabs.com/newgrouppage...
- Ø1/2" Posts: www.thorlabs.com/newgrouppage...
- Ø1/2" Universal Post Holders: www.thorlabs.com/newgrouppage...
For more photonics how-to videos, visit www.thorlabs.com/newgrouppage.... - วิทยาศาสตร์และเทคโนโลยี
You guys should make more videos like this. They are so good for optics newbies like me!
More videos like this please!
Very useful refresher.
Great video series. Would be nice to add a video for alignment through a rotating periscope arm (as in Bergamo II multiphoton scope).
Thank you very much for your suggestion and for letting us know you like the videos!
Brilliant project Congratulations
Really useful. Just it's what i need
It was really useful
Thank you for the instruction
We're glad you found it helpful. If there is another demonstration that would interest you, let us know!
Really useful video good job 👍
Great video! Thanks!
Thank you for the feedback - we are glad you found it helpful!
Great video laser alignment i like
That was extremely useful! May i ask if the second technique is also used for class 3 or 4 lasers?
Thanks for your comment! The same mirror adjustments can be used to align Class 3 and 4 lasers, but we recommend operating the lasers at low powers for safer handling while aligning free-space and unenclosed laser beams. In our videos we have kept our laser power
Nice...thanks for sharing this!
Could you please list the P/N of items you used for this demonstration!
Thanks a lot.
We're glad you found the video helpful! We've added a list of components to the description. You may need to click Show More.
Thanks Bill.
Nice tutorial. It would be great to add a video explaining how to align laser beam into the Off-Axis Hole Herriott Cell Mirrors: CM254-100CH3-M02 in an easier way.
Thank you very much for your suggestion! Would you give us a better idea of your application's alignment challenges? For example, are you using the mirrors to create a Herriott cell for just increasing the path length, interrogating some substance, or something else? What wavelengths are you using for your alignment and measurement?
Nice tutorial! I have same approach with two irises to align one from several possible laser diodes (placed on magnetic holders) in one measurement system. As I see, my "customers" (students, colleagues) are coming quite clear with this procedure even not being physicists. Alignment of IR lasers is not so obvious but still possible.
However.. I should say that from point of view of a laser safety the procedure is "a bit"... not safe..
In real life many people align the full/high power laser beams in same way (have seen it many times). And it is good if they (and especially spectaculars) have safety glasses on and the table has safety shields on sides.
So - I would include using a shutter or at least a beam block (I use magnetic one which is easy to slide in/out of the beam) while placing some elements in the beam.
As a suggestion for a next "tutorial" - installation of laser diodes in heads! With LD/PD AG/CG recognition from datasheet, setting of limits )again from datasheet and adjustment of PD sensitivity. Also choice of collimation lens and a collimation procedure of the laser beam (simple or with shear plate). That is what I show to PhD students several times a year. And myself I have learned it by hard. And still do (mode hoping even in temperature stabilised mounts is driving me crazy).
You are correct that best practice typically includes reducing the power of the laser to the lowest level needed to perform the alignment, wearing laser safety glasses appropriate for the wavelength and power of the laser emission, and using beam blocks or laser shutters to prevent stray reflections from hitting labmates unexpectedly. Getting in the habit of doing these things is wise, even in situations such as this one where the laser power was low enough that that the human blink response should be sufficient.
Thank you very much for your comments and suggestions for future videos! We love to receive suggestions!
@Tush Thanks again for your comments! We thought you would like to know that our new step-by-step TO can laser diode setup video ( th-cam.com/video/YshMuSfIcBQ/w-d-xo.html ) was inspired by one of your suggestions. We hope you like it, and we greatly appreciate the recommendation! Let us know if any other topics have come to mind.
@Tush A new Video Insight, Setting Up a Pigtailed Butterfly Laser Diode ( th-cam.com/video/LAixCOso-FE/w-d-xo.html ), demonstrates the procedure for installing the laser in the CLD1015, which is a combination butterfly mount, laser diode driver, and temperature controller. The video includes tips and tricks for installing the laser, including guidance for applying thermal grease, as well as the procedure for entering the thermistor values and setting the maximum drive current. Thanks again for your topic suggestions!
Such a nice video, thank you so much! Everything that you presented is also feasible for high power lasers/Class4 Lasers, you just need to wear protective glasses + use (for instance IR lasers) those fluorescence cards, right?
It is correct that the same mirror adjustments can be used to align Class 3 and 4 lasers, but please always follow the guidance from your facility's laser safety officer when using high-power lasers. In many cases, the recommendation is to use low powers for safer handling and to preserve the lifetime of IR cards while aligning free-space and unenclosed laser beams. However, it is important to note that, when the alignment is performed at reduced laser power, the alignment might need to be tweaked once full laser power is applied.
Irises are another special concern while working with high-powered lasers. We used black-plated iris blades (leaves) in the video since our laser power was relatively low. This coating will discolor, and the leaves can deform when higher laser powers are absorbed over long periods. We typically use stainless steel leaves when using higher power lasers to reduce the amount of light that gets absorbed. However, bare stainless steel iris leaves are typically more reflective than the black-plated leaves. When placing irises or any other component in the path, it is also important to check for stray reflections.
@@thorlabs thank you for your answer! " However, bare stainless steel iris leaves are typically more reflective than the black-plated leaves." -This is why I am/was thinking of using the black plated iris blades for alignment and then (with turned off laser of course) take them out of the beamline (but keeping the post) so that they wont stay in beamline forever...
@@ColJack100 You may find it helpful to know that our Tech Support team suggests switching to stainless steel iris leaves if the incident laser power can raise the temperature of the black-plated leaves above 250 °C. Whichever irises you choose to use, it may be possible to fully open them, instead of removing them from the setup, after completing the alignment. This approach assumes the beam is small enough to pass through the iris without clipping. (Note that for Gaussian beams, the 1/e^2 beam radius includes ~86.5% of the beam's optical intensity. A radius that is a factor of ~1.5 larger includes ~99% of the beam power.) Some people like to keep the irises in the path so that it's easier to re-check the alignment later.
Great video for beginner. I am facing problem of mounting optical components (Lens and mirrors) at accurate distances(in mm). It would be grateful if you can give some suggestions.
We typically follow a few steps when we need to accurately position optical components. First we think about the adjustments that will need to be made to accurately position and orient each optic. Sometimes just one dimension, like distance along a single line, will need to be adjusted. Sometimes translation along all three Cartesian axes will be needed. In other cases, angular adjustments will be required. We identify the minimum number of necessary degrees of freedom for each optic, since the stability of the setup is best maintained when each optic’s degrees of freedom are kept to a minimum. We then select the required combination of rails, translation stages, rotation mounts, and kinematic mounts for each optic.
After fitting each optic in the required combination of optomechanical components, we’ll place the mounted optics at positions roughly identified using a ruler. We will then adjust the optics’ orientations and distances while monitoring the effect of the adjustments on the light in the system. We take this approach since we find that making adjustments while watching for particular optical effects is usually easier and more effective than relying on precisely measured distances between optical components.
As an example, in a recent Video Insight (th-cam.com/video/xuzuFPl8rh0/w-d-xo.html ) we used an optical effect called speckle to determine the focus locations of a couple of mounted lenses.
@@thorlabs Thank you very much for detailed information.
I'm looking into a change of career and laser alignment is a prime field for the plucking.
We’re glad you enjoyed the video! You can find our current job openings at www.thorlabs.com/careers
When aligning a telescope on an optical table, we have set out optics up that go (using I for iris): M1 M2 I1 I2. I have been taught to align M2 to I1 and M1 to I2, instead of the usual M1 to I1 and M2 to I2. Why is this? Haven't been able to find a good explanation online
As your experience demonstrates, there are often multiple ways to reach the same goal. A couple advantages to the approach you described are 1) the user can first align the irises and then use the same iris to position the second mirror and perform the fine adjustment and 2) it can prevent the beam from inadvertently falling off the second mirror and/or iris during the adjustment when there are larger spacings between parts.
I personally use the approach I showed because I try to keep my steering mirrors and first iris in close proximity whenever possible. It is also easier for me to visualize the first mirror placing the beam at one point on the intended path and the second mirror correcting the beam path to make both parallel. Sometimes I forget which way I need to turn the adjusters so the more I can visualize the beam pointing in my head, the easier it is for me to achieve the intended alignment.
Nice Bill. Can you do one on the XYZ fiber stage 😁
Great suggestion - thank you!
Please tell me sir
What to do if we need straight line between two mirror and straight line in irises perfect 90°
Alignment is performed with respect to a reference, and the alignment precision is determined by the precision of the reference. Since a reference needs to be chosen, the first step is to determine exactly how close to 90° the angle is really required to be. When that is known, a reference that provides that level of precision must be identified.
In our video, the holes in the optical table were the reference we used to define straight paths parallel to the table. Then we relied on the machining tolerances of the bases, post holders, posts, and irises to define beam height. In many cases, that level of precision is enough, but in many other cases it is not.
The precision could be increased when the optical path is confined to a cage system ( www.thorlabs.com/navigation.cfm?guide_id=2002 ). Another step could be custom tightly-toleranced baseplates with alignment pins to set the post (www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=9079) locations.
Hello. Is there a equipment available to buy to make the process more "direct"? I work on a molecular fluoresce group in my country and we have been suffering to align the laser in the proper way for it to enter on the microscope correctly. When I went to a laboratory to do a Raman spectra of my material the had the laser (cobalt 473 nm and other to lasers), and the were all connected to a piece that directs the laser to the microscope perfectly. I have been search for that equipment name but I cannot find it. Could someone tell me? Thank you.
@henrique76170 Thorlabs integrates a device like this into some of our microscopes, but we do not currently offer a beam aligner or stabilizer as a standalone product. However, the possibility of developing this type of product is being discussed. It would help us if we better understood the laser alignment and/or stability challenges of your application, as well as the operating environment. For example, whether your setup is mounted on an optical table and in a temperature and humidity controlled room, or is being operated under different conditions. Would you be willing to share some more information about the specific requirements of your application? Please also consider contacting our Imaging Tech Support team (imagingtechsupport@thorlabs.com) to discuss your application.
Thank you so much for answering. I will give more details on the e-mail you sent me. I would love to explain all my difficulties at the lab, and if possible, buy equipments that can solve those problems. Again, thank you.
Why do you put mirrors between the laser source and the Irises instead of introducing light directly from the laser source to the Irises?
It could be possible to align the laser source to the irises if you have 4 axes of adjustment on your laser (horizontal translation, vertical translation, pitch angle, and yaw angle). However, there are often times when it is not possible to provide that adjustment to the laser. There are also times when the beam path requires some tweaking due to small misalignments of components within the system. As a result, the two mirror approach demonstrated in the video is a common way to ensure the laser beam travels in a straight line, but it is definitely not the only approach.
@@thorlabs Thanks for your guidance. It is very helpful for me.
In this alignment polaris is best to adjust the beam directionality
@rumadebnath48 The Polaris mirror mounts definitely have their advantages, especially when it comes to maintaining alignment after temperature swings. We are really glad you like them. Definitely let us know if there are additions to the Polaris family you would like to see.
much more i need
Please let us know if you have an idea for a video that would be helpful to you. We always welcome topic suggestions!
can i know about the product name under the mount?
Each of the mounts was screwed to a 0.5" diameter optical post that was held by a post holder. Two types of post holders were used in the demonstration. The laser and irises were held by post holders designed to be screwed into an optical table, breadboard, or base. The irises' post holders were screwed into BA2 bases. The mirrors were held by a different type of post holder, which has a built-in swiveling base.
Optical Posts: www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1266&YVI=1
Post Holders: www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=1268&YVI=1
BA2 Bases: www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=47&pn=BA2&YVI=1
Post Holders with Swiveling Bases: www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=1982&YVI=1
We've recorded a couple of Video Insights filled with tips and tricks that we've found helpful when working with posts, post holders, bases, and mounts. If this sounds interesting, please check them out!
Mounting Your Optomech: Bases, Post Holders, and Posts (th-cam.com/video/4xZmGyMsQNo/w-d-xo.html)
Tips for Bolting Post Holders to Optical Tables, Bases, and Breadboards (th-cam.com/video/HyUXsH1zuIk/w-d-xo.html)
Thanks for your reply. Also I'm wondering that IR laser light by your product such as M780F2 or M1050F2 can be seen by our eyes.
@@zaehyuk The longest visible wavelength is different for everyone, but it is around 700 nm. The 780 nm light from the M780F2 may or may not be faintly visible to some people. The 1050 nm light from the M1050F3 is invisible to people.
Different tools can be used when working with invisible beams. A common tool is a laser viewing card. When the card's active area is put into the beam path, the card will glow at the spot where the beam is incident. The fluorescing material used in IR cards is also used to make alignment targets for general use. Another option is to image the beam. For the wavelengths you are referencing, you can try using a cell phone camera. IR viewers are also useful for imaging visible and IR light up to approximately 1700 nm.
Laser Viewing Cards: www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=296&YVI=1
Alignment Targets: www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3201&YVI=1
IR Viewers: www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=14844&YVI=1
What about infra red lasers where its not visible to the eye?
When the laser light is not visible to the eye, IR cards ( www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=296 ) can be used to perform the alignment. When an IR card is inserted in the beam, the card will glow at the spot where the light is incident. One approach to aligning an IR beam is to use the IR card to track the beam from the source, to each mirror, and then to the first iris to minimize the chance of stray invisible reflections. Then the card can be used while tuning the mirror mount adjustors to align the beam to through the irises.
Another option is use an IR viewer ( www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=14844 ). A person views the scene by looking through the eyepiece of the IR viewer. The IR viewer images the scene using visible and near-IR light up to 1700 nm, so it is possible to see the beam spot on the optical components.
Would it be helpful to see a Video Insight demonstrating the alignment with IR light?
@@thorlabs I would appreciate a video on alignment with IR light. One of the main experiments in my lab uses light in the mid-infrared regime generated from the signal and idler beams of a femtosecond pulse laser and I will eventually be teaching how to use it. Like you mention, I use a combination of a guide beam (laser diode module), IR card, and IR viewer. I also use a power meter to check the MIR beam throughout the path, finally ending in a pinhole with a photodetector. There are certainly a lot of parts to a complicated experiment and you sometimes don't realize it until you have to teach someone else!
I just started training new master's students in my labs (using some of your excellent videos!) and this week is beam alignment and common optical components. It is great to have these videos for students to refer back to or to see an alternative explanation, so I would love videos on any of the steps I mentioned above!
@@garrek Thank you very much for sharing your topic ideas! Not only is it great to know what demonstrations you would find most useful, but it is also helpful to have an idea of the situation in which the techniques are used. Do you have any unique tips or tricks that you like to use? One that we’ve found people appreciate in the MIR is using the table to cool the liquid crystal IR card.
We remember from a previous comment that you were considering folding these videos into your master's students' training. We’d love to hear how that goes and if there is anything else that would help complete the list.
@@thorlabs I also use the table to cool my IR card. Another tip if you're using a phosphor-coated sensor card (for NIR beams): sometimes the beam can appear diffuse on the card, making it difficult to know where the beam center is. I will sometimes open and close an iris repeatedly to see which side of the beam the iris cuts first and adjust the path until the beam is cut by the iris evenly, or until it looks like the brightest point is in the center. It's kind of hard to explain in text, and these cards can be a little tricky to use.
So far the students I'm teaching are still learning the basics. Also, I'm in Japan so English is not anyone's first language (except mine!), but it's really helpful that the presenters in the videos talk slowly and clearly point to each object they are talking about.
@@garrek The iris-adjustment technique is also a good one!
We try to film the videos with an international audience in mind, and we're happy to hear that our presentation style is helpful to your students. It's important for us to hear what approaches students find to be effective to ensure we continue to include them. We understand if your students use the videos to learn English-language terminology, but are they aware that we also upload our own closed captions in various languages, including Japanese, in an effort to help bridge the language gap? Some of the newest videos may still have auto-generated captions, but we replace these with corrected captions as soon as we can.
Can it go to 100 yards far?
@Koobmeejyaj3143 After alignment, the beam should ideally travel parallel to the table’s surface and along a line of holes in the optical table. In a perfect world, the beam would continue to be at this height and follow this line for 100 yards or more. However, the irises, the holes in the table, and a human’s ability to precisely position each component are all imperfect to some degree. The errors contributed by each will result in a beam that is slightly off from the ideal beam path, and the amount will be more obvious at farther distances. The error can be reduced by placing the two irises as far apart as possible when performing the alignment.
Info
Make sure your beam is traveling in a straight line. 😂
Thorlabs, can you people make a real life wishing machine that can grant all wishes like the one in the science fiction movie "Invisible Dad" and let it be on the market?
where are your glasses young man?
We absolutely recommend wearing laser safety glasses as directed by your facility's laser safety guidelines. We chose not to wear glasses during this demonstration, since we used a class 2 laser with power