Here is the link to where I posted my thesis paper + the manual.
https://sites.google.com/site/anyakash87/physics/optical-tweezers
It is written specifically for our equipment, so I don't know if it would be much help. Also it is written for college sophomores/juniors with no experience...
Ah I was meaning to thank everyone who helped me build mine. That was extremely nice and finally allowed me to graduate :D
@hopeful: If you are an undergrad, I can probably help you out. I have written a manual on how to build a tweezer. But if you are a grad/have some optics experience...
Oh and the cluster of the particles on the bottom is where a beam used to be before I moved it. I can also use the beam to grab particles one by one and arrange them in shapes.
Hi Andy! Thank you a lot for your pictures. They were really helpful, since now I had a better idea of what I was looking for, looking at the beam. I finally got trapping! It was really really exciting. The trap was very strong and kept literally sucking in the particles from within of like...
Oh okay, so that's just diffraction? I do send a beam through a small circular lens that I put into the diode module for collimation. Where shall I keep the telescope then? At the position that gives me a more pronounced diffraction pattern (far away from the laser) or near the laser where I get...
Also I am sorry the pictures of the beam are so huge. I tried making them smaller on the host website and then add them in here again. but they wouldn't change
And here is the beam pattern that I see when beam comes out of the laser and hits the first lens after the focal point (this one is when the path length of the beam is rather short). I am not sure why I get the rings.
Here is how the beam profile changes as it travels longer distances. At...
Here is the image of my whole setup. I am using a diode laser. 100x oil immersion objective and the telescope lenses I currently use are 50mm and 250mm focal length.
And here is where I am trying to trap them. I am planning on making sort of a flow cell once I can actually trap something...
My setup is very simple ( it is inexpensive for one and then my professor wants me to set it up and write a manual so students in the advanced physics course would be able to set it up themselves --- so it has to be simple). It is all in one plane - horizontal. I personally think that the...
And I did figure out the mirror had nothing to do with the pattern :D it was all in the path length difference... Thank you ! I still don't know why the path length difference matters so much but it's nice to narrow it down :)
Andy, that's strange that we can see the beam then. Maybe our diode is not 780 nm after all :/ That's what the specs say though... (By the way I did not find out that I can see the beam until one day I forgot to put the safety glasses on...) I always wore the glasses and used to use cheap cell...
Yea, I look at the beam when it hits a white piece of paper. It is red. Since I turn the power down to 2-3 mW it shouldn't be harmful right. Usually when I am working at the high powers I use glasses.
Thank you both again very very much. I didn't expect to receive that much useful information and advice!
I think my mirror is the front surface. I have seen both front surface ones and non front surface ones and and the ones I tried look like front surface. Is there a way to check it?
The...
The beam is an 80 mw diode laser... pretty cheap one. I think the diode only cost $30... It is supposed to give out an elliptical beam.
I have it collimated and the beam looks pretty circular (to within you can't tell that it's not circular) and about 1.5-2 mm in diameter. I was going to use 2...