Lab 4 Prep Package
Tuesday, October 6, 2009
Sunday, October 4, 2009
Lab 3 - 5 October 2009
PDF's for Lab 3 are available:
Lab 3 - Plan of the Day
Lab 3 - Laser Beam Conditioning
Lab Self Assessment
Lab 3 - Plan of the Day
Lab 3 - Laser Beam Conditioning
Lab Self Assessment
Thursday, October 1, 2009
Lab 3 Prep Package Available
Lab 3 Prep Package
Note that there is a video to view. It is one of the Feynmann New Zealand lectures on QED where he introduces his theory to a lay audience. The link for this 98-minute streaming video is
Feynmann video: Robb Memorial Lectures Part 1: Photons - Corpuscles of Light
Note that there is a video to view. It is one of the Feynmann New Zealand lectures on QED where he introduces his theory to a lay audience. The link for this 98-minute streaming video is
Feynmann video: Robb Memorial Lectures Part 1: Photons - Corpuscles of Light
Wednesday, September 30, 2009
Lab 2 - 30 September 2009
First off, how cool is the sign on our lab door?
(not the fire extinguisher part)
Lab 2's materials are at these links:
Lab 2A - Optical Table Fundamentals and Component Placement
Physics 492 Self-Assessmment
For convenient downloading you'll need a free Google account. Google is not evil, just demanding.
The class was about the table and putting components on it. We started by getting used to working in gloves with our tools and building up some simple mount bases, then placing them at assigned locations. We finished with full builds of several beam splitters from parts still in their wrappers. A quick design conference between the two teams divided up the table and reached agreements on where beamsplitters will go to provide beam distribution to three separate experiment areas. Here is one of the beam launchers at its assigned location, performing its function. Can you see a piece of Doug?
What, you may ask, is the white and blue stuff? The white is some lens tissue that came with the beamsplitter in its box being used as a compliant load-bearing surface for the beamsplitter to sit on. The tissue in turn is taped down with some small cut pieces of blue painter's tape to keep it from moving as the glass is placed. We don't want metal to touch glass if we can avoid it. Without the paper, the glass would sit right on the anodized aluminum shelf, and very high stresses would be developed at the three (why three?) contact points, leading to microscopic damage. But the paper is compliant - it deforms somewhat - so the load through the glass to the shelf is distributed over some area. It is easy enough to protect the glass in this way (this time!) and a good habit to always be thinking about how the glass is being touched. The beamsplitter cube is held in place by a nylon-tipped set screw threaded through the upper shelf which compresses it against the tissue paper. This set screw must be only snug and not turned down tightly - again to avoid possible damage to the glass.
The layout design conference was an exercise in parallel coordinated work by the two teams. We don't have time (nor inclination necessarily) for everyone to do everything. We need to do some parallel processing. In this case each of the two teams sent 2 representatives to the whiteboard to agree on how to divide the table up and arrange how beams would be delivered to several experiment areas with the beamsplitters. The result:
Lab 3 prep package will be up shortly. Part of the prep will be to watch one of Feynmann's videos. The video itself is over an hour long, so be sure to schedule some time for this. The video is online and streams to your computer like YouTube. Also there will be a narrative with questions for you to work related to the video.
Next week we'll take a little time exploring the concepts in the video and relate them to what is happening on the tabletop.
(not the fire extinguisher part)
Lab 2's materials are at these links:
Lab 2A - Optical Table Fundamentals and Component Placement
Physics 492 Self-Assessmment
For convenient downloading you'll need a free Google account. Google is not evil, just demanding.
The class was about the table and putting components on it. We started by getting used to working in gloves with our tools and building up some simple mount bases, then placing them at assigned locations. We finished with full builds of several beam splitters from parts still in their wrappers. A quick design conference between the two teams divided up the table and reached agreements on where beamsplitters will go to provide beam distribution to three separate experiment areas. Here is one of the beam launchers at its assigned location, performing its function. Can you see a piece of Doug?
What, you may ask, is the white and blue stuff? The white is some lens tissue that came with the beamsplitter in its box being used as a compliant load-bearing surface for the beamsplitter to sit on. The tissue in turn is taped down with some small cut pieces of blue painter's tape to keep it from moving as the glass is placed. We don't want metal to touch glass if we can avoid it. Without the paper, the glass would sit right on the anodized aluminum shelf, and very high stresses would be developed at the three (why three?) contact points, leading to microscopic damage. But the paper is compliant - it deforms somewhat - so the load through the glass to the shelf is distributed over some area. It is easy enough to protect the glass in this way (this time!) and a good habit to always be thinking about how the glass is being touched. The beamsplitter cube is held in place by a nylon-tipped set screw threaded through the upper shelf which compresses it against the tissue paper. This set screw must be only snug and not turned down tightly - again to avoid possible damage to the glass.
The layout design conference was an exercise in parallel coordinated work by the two teams. We don't have time (nor inclination necessarily) for everyone to do everything. We need to do some parallel processing. In this case each of the two teams sent 2 representatives to the whiteboard to agree on how to divide the table up and arrange how beams would be delivered to several experiment areas with the beamsplitters. The result:
Lab 3 prep package will be up shortly. Part of the prep will be to watch one of Feynmann's videos. The video itself is over an hour long, so be sure to schedule some time for this. The video is online and streams to your computer like YouTube. Also there will be a narrative with questions for you to work related to the video.
Next week we'll take a little time exploring the concepts in the video and relate them to what is happening on the tabletop.
Monday, September 28, 2009
Michelson Interferometer
After the scheduled class time was over, some of us went over to another lab to take a look at a Michelson interferometer. This is an iPhone photo taken looking upstream at the fringes formed by this interferometer. Everyone was able to safely put their eye at this location and see the fringes for themselves. Safe because the source was an incandescent light with a narrowband filter and a diffusor screen - never look upstream at a laser. We had a lively discussion on how it is that "which-way" ambiguity having to do with the 2 arms of the interferometer and small tilts in the end-of-arm mirrors give rise to these fringes. For example, the presence of 7 fringes means that the two mirrors are misaligned by 7/2 wavelengths from ideal - each half wave gives one fringe - or by (7/2)*500nm = 3.5 microns.
Lab 2 Prep Package Available
Lab 2 Prep Package
Instructions: do the work in the package, recording in your lab notebook. Be prepared to verbally report out at the beginning of class Sep 30.
Sunday, September 27, 2009
Lab 1 -- 28 September 2009
PDF's for the first lab session are available:
Lab 1A - Introduction to Physics 492
Lab 1B - Lab Safety & Fundamentals
Lab Self-Assessment
A simple demo is on the table reproducing Young's double slit experiment. First the laser beam is expanded and collimated through 2 simple lenses to form planar wavefronts / straight rays. The expanded and collimated beam then passes through a glass slide with a double slit inked on it. Then the beam propagates to the end of the table where it illuminates a simple screen to show the classic interference pattern.
Photos taken with an iPhone in low light - handheld and with its autofocus algorithm trying to sharpen edges so they are a little blurry.
Lab 1A - Introduction to Physics 492
Lab 1B - Lab Safety & Fundamentals
Lab Self-Assessment
A simple demo is on the table reproducing Young's double slit experiment. First the laser beam is expanded and collimated through 2 simple lenses to form planar wavefronts / straight rays. The expanded and collimated beam then passes through a glass slide with a double slit inked on it. Then the beam propagates to the end of the table where it illuminates a simple screen to show the classic interference pattern.
Photos taken with an iPhone in low light - handheld and with its autofocus algorithm trying to sharpen edges so they are a little blurry.
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