User:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2009/05/22/Laser diode

Koch meeting

Koch and I had a meeting on Wednesday that illuminated lots of things. One thing in particular was the fact that I do not write negative results in my notebook. I'm not sure why I do this but it could be that I don't think I should write negative results in a public notebook. This of course is silly because I could not remember what I did and redo something that is wrong. So, I will change this and today's entry will be a culmination of lots of negative things I've done of the past few weeks with the laser.

Also, this is a bit esoteric and may not mean anything to anyone but me but, for some reason I don't ask for help enough. I believe this stems from my belief that I need to be able to do everything on my own before I feel like I can graduate. This is of course a silly mentality and can only lead to wasting time.

That's pretty much all we talked about.

Laser

I emailed the people at PLT with some questions. Here are the questions and answers.

• What type of grating is used in the diode if any? What is the pitch?
  • No grating, no pich this is one stripe. The chip 600um wide.
• What type of lens is used for the FAC collimation?
  • GRINC cylindrical lens, N/A=0.5, 250um diameter
• What type of antireflection coating if any, is on the lens?
  • 600 to 800nm Optical AR coating
• Where is the diode element located with respect to the front face of the package?
  • Sorry no measurements
• How large is the diode element?
  • 600umX1200umX110um
• Do you have a typical spectrum for the diode we have?
  • No, Sorry.
• We are getting striations in the diode beam, what is causing this?
  • Could you send picture?

The guy that responded is named Peter and his number is:

• 805-962-1266

Mistakes

I'll post some of the mistakes I've made here. Hopefully I will have time to list them all.

• I have never worked with high powered lasers. Because of this, I've never worn goggles when I've worked with lasers before. When I went to work with this laser, I was wearing my goggles and I thought that the beam I saw through them was the correct beam lasing from the diode. It turns out this was wrong. The beam looked orange and in fact, it is an orange beam I was trying to fuss with for so long. In fact, this was the wrong thing to do. The beam coming from the laser is supposed to be red and I should have seen a red beam through the goggles if it was powerful enough to bleed through them.
  • Take home: Wear goggles but never think that what you see through them is the correct beam.
• Because I never realized that the beam I was looking at was not the correct beam, I did an insane amount of optics to try and collimate it and send it through the microscope to tweeze. This proved to be very trying on me because I did everything I could to make it work but it never did. The following are notes on what I did and hopefully I will return to fill them in later.
  • Aspheres
  • Cylindrical lenses
  • Objectives
  • Building an objective
  • High NA condenser
  • Spatial filtering
  • Failed collimation attempts

Diode basics

Fill in what I learned.