The last few months in a nutshellThe last few months have been so busy. I was barely in the lab room after September. Here's a summed up liste of what I've done up to recently.
If you would like to see some photos of the symposium in San Jose, please visit the main website for the Laser Teaching Center. Click on the Symposium tab, and browse down to the newwest symposium entry, 2007.
2007.08.08Entry #: 011
Accomplished!I coupled my first fiber from start to finish earlier this evening. The fiber is use to set up the light mask. I did my victory dance...and giggled a whole ton. Excitement!
2007.02.08Entry #: 010
IssuesOur source decided to have issues by glowing but not lighting up. The water froze around it and now we're baking for the fish. Yay.
2007.07.31Entry #: 009
Yance and Brookhaven National LaboratoryThree things worth mentioning since the las entry.
2007.07.23Entry #: 008
Complete 2Today is a beautiful day...minus the lousy weather. Jason and I have finally completed collimating the +kv line, though that was because we gave up after 9 iterations of recollimation. It was a pain and I think I was begining to have hallucinations.
After having settle on the +kv alignment issues, we explored the mystery of the fiber amplifer problem. I don't quite remember if I had mention this in earlier posts, but the fiber going into the -kv line decided to crap out sometime last week. It would not work and despite our effort in reviving it, it just "died". Today, however, after a full day of bea, profiling, the fiber decided to work. Jason tested it with many different methods, such as hooking the patchcord up and what not... and it amazingly worked wonderfully during each test. We hope the fiber will be good tomorrow so that we can realign bichro smoothly. It would be terrible if the fiber suddenly decides to act up again.
ABout my Fabry-Perot... Hal has yet to solder the the wire to the outside of the PZT, but I'm not too worried or desperate for it. I'm still trying to mend the optics after my last mishap. While we're on the subject of soldering, Hal suggested that I take the mechanics workshop...which I thought is only offered to graduate students. I think I'll look deeper into this.
Random thoughts of the moment:
OH!!I made a visit to Christina Chu's Lab (Matt Durham's Lab) so that she, Mallory and I could get lunch together. I love that lab because it's so clean! On a bad note, everything in there requires one of taller height. Unfortunately being someone not so tall, I was unable to help crank the cathode (?) or look into the vaccum system without some sort of assistance. I realize from this that I've definitely picked the right field and lab group to join this summer. Most things inside the lab are around my height, and if I needed the assistance (though very rarely), there's always a stool somewhere within my reach.
ANDI started compiling information for my california poster. I'm excited and nervous because:
2007.07.20Entry #: 007
CompleteSo it's been a while. I have finished building the Fabry-Perot. I took some measurements and indeed, we have the beautiful peaks. The peaks were such a pain to get at first because the laser needed to be perfectly aligned, i.e. the retro beam needs to be aligned to the original. After 3 days of hard work, many frustration rants, I completed and I got these wonderful peaks that I will put up someday.
Now, the next task is to realign the +kv and -kv lines of the experiment. Jason and I finished the -kv last night (thursday) so now we have the -kv to do. This is the painful one because the beam waist of the +kv needs to be exactly the same as the -kv (requirememnt for bichro to work). Jason and I anticipate at least a full day's worth of beam profiling and what not. I think we're still taking off early though because I made plans to go out with my friends tonight, and Jason has swim practice.
Anyhow, going to go now. Ta-ta.
To sum it all up, I messed up the mirror alignment in our experiment...which set the group back for two weeks or so. We need to realign the two telescope and all the tiny little troublesome mirrors.
Suddenly optics seem like a pain.
2007.07.05Entry #: 005
Today, I started to assemble the Fabry-Perot resonator together. I glued on the Piezoceramic Tube (PZT) onto the Invar, as Hal instructed. I will post up a diagram of how to do so in the next few days or so. The Epoxy was being such a pain. I had to stay put to hold the PZT in place for nearly 30 minutes. The direction said only 15 minutes is needed for the epoxy to set, and an additional 15 minutes to dry. The epoxy did not set after 15 minutes, nor did it set after an additional 15 minutes. By that time, I placed a level indicated ontop of it to keep it in place, and to make sure the PZT is mounted on evenly. After lunch, the PZT setted in place and I skipped off to congratulate myself.
Returning, I mounted on the first mirror. It is the one mounted ontop of the PZT. This mirror will be variable as we sent current across the PZT...which reminds me, I still need to solder another wire onto the outside of the PZT so that a potential difference is created. The second mirror will be assemble later today, or if not, early tomorrow morning. That one will be a tad more difficult as I will have to vary it to find resonance before I can secure it onto the invar. Wish me luck!
2007.06.29Entry #: 004
Fridays are the hardest to work during the week. This morning, Jason and I quickly finish taking photos of our beam on the two screens, MCP and Phosphorus. The two sets seem to be alright. We took for each set, a full collimation, one with bichro and hiigh intensity molasses, two of just bichro and dopplere separately, and one background.
We had to reset the phase on the lock, which was interesting yet a bit of a pain. Jason had difficulties locating the phosphor screen with the camera, and I was unable to extract the beam intensities by subtracting the background from the others. Overall, it's been quick, but since we don't have the lab for the rest of the day, we're not going to get much else done.
My Fabry-Perot will have to wait for another week before I am able to assemble them together. I need to scan the invar and the PZT to locate the peaks. I'm excited. Hal also showed me how to assemble them together. I hope it'll be done by next week so that Claire will have it to use.
Hal showed me how to assemble the PZT onto the Invar. It's not difficult, but we do have a slight issue. We need to glue the PZT onto the Invar without the PZT touching the invar completely. He suggested that I slip a small piece of paper in between the two and then glue the PZT to the invar. After the glue dries, remove the piece of paper. It seems like a good idea, but we happy that the paper is not stuck to the PZT because that may cause some sparks.
Other than that, during group discussion, the groupd decided that the back mcp-phosphor screen needs to be re-engineered. I think it'll be a fun project for Christina and I. Yay!
2007.06.27Entry #: 003
Optical Tweezers and Geometrical Optics
Short recap of what has happened so far in the week.
On Tuesday, a fellow REU student, Dan D'Orazio gave an informal lecture on geometrical optics. He started off with Fermat's principle and then from that, derived some of the known laws in optics. I believe the one he derived on the board is the law of reflection. He also derived the lens maker's equation. He started briefly on thick lens geometry, and touched a little bit on optics matrices. He will finish the rest of his presentation tomorrow, Thursday June 28th at around 10:30 AM. I'm excited because I actually have no educational background on this subject. We glossed over it during classical physics and didn't bother much with it in the 300 Optics course. It doesn't seem very intricate, except for the nodal areas (I think that's what they call it). I'm just excited to learn more. -- A detailed entry will follow the second addition of Dan's presentation.
On Wednesday, I missed the early part in the morning because I was working on the lithography experiment with my labmates, Claire and Jason. They had me do some beam alignment (only the retro beam) and locking the laser. Both were very successful! Ontop of that good news, Claire, Jason and I are ecstatic that we didn't have to do too much of realignment for the molasses or the bichro. The beams seem to be fine and so we had a fresh start today with gathering the data. I will provide images of these in the near future in, once again, a detailed entry dedicated solely to Lithography.
In the afternoon, I went to a couple of presenations on optical tweezers by Dr. Urszula Golebiewska and Hamsa Sridhar, fellow highschook Kaser Teaching Center (LTC) students. Dr. Golebiewska recieved her PhD on Optical Tweezers and Hamsa Sridhar recieved many awards for her research on optical tweezers.
In general, optical tweezer is a method of trapping particles through the use of forces exerted by light such as lasers. Hamsa has a very detailed page on this particular sibject, which you can find here. I will write down my thoughts on these two presentations, by Hamsa and Dr. Golebiewska in a more organized entry.
Other methods of trapping such as laser cooling, which I've been doing for quite a while in Hal's group without great knowledge, and Bose-Eistein Condensate (BEC) by Dr. Dominik Schneble. I went to a small presentation by Dr. Schneble and will write what I've absorbed on BEC over the next week or so when time permits.
I seem to be making a lot of promises for future entries and very slow pace at materializing them. I apologize. On another note, please feel free to send in emails if you've discovered something wrong within my entries, i.e. misunderstanding of the concept on my part. I will only learn when I'm told I'm wrong.
Till next time, cheers!
2007.06.23Entry #: 002
Read, Learn, Teach
For the past weeks, I've been doing a lot of research and I also have been
doing a lot of explaining, (Hal believes that in order to grasp the
material one must be able to teach it.) Once again, the topic is the
difference in the free spectral range of the confocal Fabry-Perot and
the non-confocal Fabry-Perot. As Clair, one of my labmates, questioned
in the month, geometrically the distiction between the non-cofocal and
confocal is very fuzzy. Under paraxial approximation, the path lenth of
the light beam in a spherical confocal resonator would be the same as the
path length of the light beam in planar resonator if the light beam
in the planar resonator travels an extra 2 path length of L, the
cavity. Note the diagram below:
The question: Suppose the beam is perfectly aligned and is transmitted through the spherical mirror on the axis, will the free spectral range in the confocal resonator be c/4L or c/2L?
I do have an explantion, but after work today.
On a side note, I did find a book on Laser Speckles, which I pesonally think is one of the most phenomenal discoveries in optics. Mainly, because now I know I'm not going blind and I'm not going insane. I will talk more about this phenomena in a few entries. If you want to do your own reading, please check out Topics in Applied Physics - Volume 9, Laser Speckle and Related Phenomena
2007.06.14Entry #: 001
Michelangelo Chipping At the Slab of Marble, (or was it granite?).
Problems Presented by Hal:
1.) Why is the Free Spectral Range for the confocal Fabry-Perot interferometer different than the non-confocal fabry-perot?
2.) At the right frequency but the wrong modes, what will the intensity peaks look like?
Answer: After having chipping away at the mountains of information, I have yet to arrive at an appropiate answer, one that Hal and the group approve.
So far, we've talked about the Gouy Phase Shift and the frequency equations along with the stability parameters. From that, Hal drifted into a new set of questions, mainly dealing with the intensity peaks. Jason and I are lost lambs at this moment, but we were suggested to read articles by "A.G. Fox and Tingye Li." Their article, "Resonant Modes in Maser Interferometer" has been referrenced over 500 times in the last 40+ years. However, it is a well hidden paper. Jason and I spent hours looking for the article online this morning but we were challenged with the heaps of references instead of the actual literature. In the end, Claire suggested the library a few levels up, and we found it compiled along with other articles in the Advanced Quantum Electronic. Excited we are.