Today in lab, we studied electric charges.  In the picture, two of the Principles of Physics students are using the Van der Graaff generator to try to levitate a small conducting ball above their hands.  Their hair is standing on end because of all the charges built up on them.

Levitating a small ball was not part of the lab procedure but it consumed more of the lab period than the required work.  The required work was by comparison less exciting.

In the previous entry, our rockets for the projectile lab are discussed.  Sometimes the weather is Walla Walla is too rainy for an outside lab in late fall.  Our solution is to shoot a small metal bearing about 2 meters from a spring powered projectile launcher - certainly not as exciting as the rockets arcing into a blue fall sky but drier if the blue fall sky has been replaced by gray clouds and cold rain.

The launchers came with a black metal table clamp made of very soft metal shown in the left panel of the picture.  That clamp bends easily and needs to be replaced.  Like many other lab projects, the first try was to 3d print a clamp from PLA. That part bent just like the black metal and was unless for the application.  Back in the days before 3d printing, we used metal for these jobs.  Dusting off the metal cutting tools, the clamps were made from ½" thick aluminum as shown in the right panel of the picture. 

Dr. Roy Campbell held a moon viewing event for kids at Frog Hollow Farms this month.  The moon was so big and bright that waiting for darkness wasn't even required.  For this event, he used the Celestron NextStar 8 inch telescope with a 40mm eye piece.  This hardware combination gives a magnification of about 50 times.

In many classes including Conceptual Physics, General Physics, and Principles of Physics, we use pen lasers for several experiments during spring quarter.  These diode based lasers are convenient to use but wear out AAA batteries at a frantic pace.  This spring, we designed and built an alternative laser system.  14 sets were constructed just after graduation this year and are ready for use in classes next year.

The laser system is made up of a housing, circuit board, and lasers.  The housing is printed on our 3D resin printer.  A simple circuit board distributes power from the USB plug to the three lasers through a dedicated slider switch for each laser.  The three diode lasers (445 nm for blue, 520 nm for green, and 620 nm for red) are purchased and screwed into the housing.  In the picture, the blue almost looks purple but to the eye, it is very blue.

During the Department Community this month, we heard from two physics majors about their research.  Chris (standing in the picture) gave a talk about his REU summer research project involving solid state refrigeration.  Nathan (sitting in the picture) talked about the nanotechnology work he has been doing during the school year.

In a number of labs over the past number of years, we use dedicated or embedded processors.  A number of these processors are expensive and hard to program.  This year, we have continued the transition to the cheap and very capable Raspberry Pi universe.  The Pi Pico is a $4 processor that can be used in our digital logic labs (in place of the Xilinx FPGAs) and for a stepper motor controller (in place of the National Instruments DAQ boards).  We designed a simple shield shown at the right in the above picture to connect switches and LEDs to the Pico.  These elements are used to test a digital logic circuit in Experimental Physics lab.

Near the end of October, the WWU Physics Department was privileged to have one of our graduates, Spencer, come back to campus and give a talk on his PhD research.  He is working on twisted graphene layers and some of the data he presented was only 48 hours old.  While his talk had some technical aspects, the combination of cool science, humor (the word "twisted" got used and misused), and a small bit of movie trivia kept the audience engaged. 

This spring we purchased a second laser engraver.  This xTool semiconductor blue laser (465nm) joins the CO2 gas IR laser (10,600nm) in our shop and adds the ability to cut thin metal which the IR laser doesn't have.  It also can mark silicon wafers so the plan is to integrate it into the Physical Electronics lab.

Over the past five years, we have boosted our shop capacity with a number of these new tools.  Each one of these computer run tools - both laser engravers, two filament 3d printers, and one resin 3d printer - has their own niche that they fill in our lab classes and equipment building.  However, if we had to select just one tool for everything, the large filament 3d printer is still the most useful.

For the last 14 years, we have been using a Scanning Electron Microscope (SEM) that uses secondary electrons for producing the image.  That SEM as been ideal for the student labs because it is cheap to maintain and robust in operation.  This past summer, we were able to find a used SEM that uses backscattered electrons to produce the image.  This SEM is more expensive to maintain but produces a different type of image which is useful for a number of labs.  In the image, a fruit fly's eye is shown magnified by 4000 times.  The left half of the image is taken using the secondary electrons and the whiskers are very bright.  The right half of the image is taken using the backscattered electrons and the surface of the gold coating over the eye is more more detailed.

There are other things going on in the department but this quarter Optics Lab is making the news since optics has pretty colors and new experiments.  As one part of the final optics lab, we tried to build a TEA (Transversely Excited Atmospheric) laser based on the designs shown in several Youtube videos.  We did not get it to work during the lab time period.

However, several of us worked on it a bit more after lab and by the second day of spring break, the laser was working well.  A picture of the laser firing is shown at the left.  The arcs between the two rods are seen nearly the length of the rods.  The very bright arc at the lower right suggests that the rods could be aligned a bit better.  The laser beam is invisible (UV) but we can see it as the green/yellow light in the Rhodamine B dye in the upper left of the picture.  We could make a dye laser using this design.

Fall is here but leaves aren't the only thing falling to the ground.  Projectiles are launching into the crisp fall air and falling back to earth as part of labs in all of the introduction classes.  In the picture at left framed by colorful trees, the Conceptual Physics Lab students are launching rocket-shaped projectiles and measuring their range as a function of angle.

As mentioned back in December of 2021, the telescope is mounted on a metal pier that reaches down through the third story of Kretschmar and shakes like a leaf in the wind.  The December vibration reduction update added air legs between the pier and the telescope.  It did reduce vibration a bit but added tracking problems.  During the past two months, the air legs were removed from the system and a tuned mass damper (TMD) was added.  As shown in the picture, the TMD is mounted near the top of the pier and is made of 6 lead bricks floating on sorbothane.  The major vibration peaks at 6 and 10 Hz have a reduction of about 5 dB in each axis.

During the summer between the junior and senior year, we strongly encourage the physics majors to participate in a Research Experience for Undergrads (REU).  A number of universities and labs participate in the program so most majors are able to enjoy this learning opportunity.  This summer we have one major and one minor doing research at different universities.  In addition to research, students and faculty are able to participate in conferences.  Both Dr. Campbell and Dr. Ekkens are attending conferences this summer.  As COVID restrictions continue to wane some conferences now have in-person options.

Raman Spectroscopy is a topic that we cover very heavily in Nanotechnology (and a bit in optics).  We have two older Raman spectrometers that we have been using for lab but we really have needed a third one based on the number of students in lab.  This year we bought one that is quite different from the two we already have.  It is green (532nm) instead of IR (985 nm) and it is sold as a number of discrete components instead of a single box.  Fortunately, a plastic file folder box is about the right size and we were able to zip-tie the components in place as shown in the picture at the left.  It will be interesting over the next few years of labs to see which wavelength works the best with our carbon nanotube samples.

The quarter of Physical Electronics lab is coming to an end.  We have made a lot of devices in lab this quarter - pn junctions, SBDs, Hall probes, and two types of transistors.  Most of them worked, but the prettiest of them all was a solar cell.  The picture shows a 2 mm view of the cell without any changes to the color.  The surface of the cell is totally dry but looks like oil on water.

The quarter of Nanotechnology is finishing up this month.  Our next-to-last lab covers magnetism so we looked at the unique shapes we could make in the fluid with magnets - both permanent and electro.  This year we set a local record from the amount of mess made with ferrofluid.  This picture was taken a few minutes before "the event."

It is once again Winter quarter so the PVC scanning tunneling microscopes are being built by the Nanotechnology class.  New for this year is a better holder for the borescope and a new power supply for the amplifiers.  The power supply is shown in the picture at the left.  It is based off a bipolar kit from Jameco and is housed in a 3d-printed box.  The new power supply replaces four 9-volt batteries for the amplifiers and a small 12-volt supply for the motor.  So far there doesn't seem to be difference in performance between the power supplies apart from ease of use.