diy Physics Blog

Author Archives: David Prutchi

OpenQuantum’s DIY Open-Source Magneto-Optical Atomic Trap

Posted on by Posted in Magneto-Optical Trap, Vacuum System
Open-source magneto-optical atomic trap by OpenQuantum

Image Credit: OpenQuantum

Last weekend, Max Shirokawa Aalto presented his OpenQuantum project at the 2023 Hackaday Superconference.  OpenQuantum’s platform is a fully open-source magneto-optical trap which can be used to collect, control, and manipulate ultracold rubidium atoms.

The design is fully open-source, and includes all the CAD files, machining instructions, electronics schematics, PCB files, firmware, and software necessary to build the apparatus for around $8k, which is significantly cheaper (by two orders of magnitude) than commercial solutions.

In his excellent talk, Max introduced the principle of atomic cooling and trapping using magnetic fields and lasers.  He then discussed the 3D-printed laser and system for observing the absorption spectrum of atoms, and touched on the high-vacuum system needed for a fully-operational trap.

Max envisions OpenQuantum to be a platform that can be used for teaching Quantum Mechanics, as well as the basis for developing new quantum technologies.  Max is looking for collaborators for his exciting project.  You may contact him at: team@open-quantum.org

The following YouTube video shows the talk that Max presented  at the Quantum Village at DEFCON 31:

In Memoriam: Robert (Bob) Iannini (1938-2023)

Posted on by Posted in Administrative, High-Voltage Power Supply, Instrumentation, Lasers, Marx Generators
Robert (Bob) Iannini, inventor, author, and founder of Information Unlimited

Image Credit: Information Unlimited

I recently learned the saddening news of the passing of Robert (Bob) Iannini on April 3, 2023, just shy of his 85th birthday. Bob, an extraordinary inventor, celebrated book author, and the mastermind behind “Information Unlimited,” succumbed to pneumonia, leaving a void in the world of amateur science and electronics.

From my high school days, Bob’s innovative paper plans and kits were my constant companions. They were more than just gadgets and devices; they were a gateway into the magical world of out-of-the-ordinary electronics, a world where possibilities seemed endless. Those kits, along with his captivating books, were my stepping stones into understanding the nuances of the ever-fascinating realm of high voltage, ultrasonics, and lasers. They nurtured my curiosity and fueled my passion.

Bob’s genius was evident in every project he conceived and every kit he designed. But beyond his brilliance, he had an innate ability to inspire young minds like mine. He made these very complex topics approachable, fun, and endlessly intriguing. With each of his creations, he imparted a sense of wonder that drove many of us to push boundaries and think beyond the conventional.

“Information Unlimited” was more than just a business; it was Bob’s legacy. It was a beacon for those with an insatiable thirst for knowledge, serving as a treasure trove of information, ideas, and inspiration for enthusiasts of all ages. In light of Bob’s passing, his wife Ann informed me that “Information Unlimited” had to be temporarily closed. However, with resilience and hope, Ann aspires to reopen its doors in just a few months, ensuring that Bob’s legacy continues to shine brightly and inspire many more.

As I reflect upon his remarkable journey, I can’t help but feel an overwhelming sense of gratitude. Bob Iannini’s indelible impact on amateur scientists, hobbyists, and curious minds across the world will forever resonate.

To Bob, thank you for igniting the flames of curiosity in countless souls. You may have departed from this world, but your legacy will continue to inspire generations to come.

A Custom Base for using the EMI/Thorn 9816B Photomultiplier Tube with the Products for Research Model TE-182 Thermoelectrically-Cooled PMT Housing for Ultra-Low Light Level Experiments

Posted on by Posted in Photomultipliers, PMT/Scintillation Processor

For a detailed writeup in pdf format please CLICK HERE

I’ve been planning some experiments with single-photon and ultra-low light levels. For these experiments I want the collection area to be large and for the detector to have very broad spectral response, so my preference is to use a photomultiplier tube (PMT) instead of a “silicon photomultiplier” avalanche single-photon detector.

I found a brand new EMI 9816B PMT on eBay® which meets my requirements. The 9816B is a 51 mm (2”) diameter end-window photomultiplier, with an S20 infrared-sensitive photocathode, and 14 BeCu dynodes of linear focused design. This tube features a very high gain of 25×106 A/lm under nominal conditions (2,200V) with a quantum efficiency of 21% at the peak response wavelength.

Integration time, and ultimately resolution and sensitivity for detecting single-photons or ultra-weak light levels are dependent on the noise floor (dark counts) which is a function of temperature. Cooling the PMT dramatically reduces its dark current and counts.

I bought a surplus thermoelectrically-cooled housing by Products for Research (Model TE-182) which is made for 2” end-window PMTs. I could not find a surplus base for the EMI 9816B 14-dynode PMT, so I decided to buy a surplus base for a different tube and modify it for the 9816B.

Products for Research TE-182 Thermoelectrically-Cooled Housing for 2″ PMTs

Clearing the inside of the base was a very messy affair. This is because the dynode voltage divider chain is partially potted in silicone, and the rest of the base is filled with expanding thermal-isolation foam. Part of the base is made of plastic, so the use of harsh chemical solvents or heat to remove the silicone rubber and expanding foam were not possible. I thus had to use a scalpel and dental picks to remove all this insulation and be able to disassemble the tube socket.

I built a new divider on a piece of phenolic breadboard . The base is wired for high voltage (-2,300V) applied to the cathode (through a 33kΩ resistor). The dynode_1-to-dynode_14 divider is built with 330kΩ resistors. As suggested by EMI, the cathode-to-focus (and dynode_1) is set at a fixed 300V difference using two 150V Zener diodes in series.

Results from a characterization run are shown in the following table. The room-temperature dark current agrees with the specified value. A very dramatic drop in dark current and dark count rate can be observed when the PMT is cooled.

For a detailed writeup in pdf format please CLICK HERE

Elegant Experiment to Measure Planck’s Constant using Photons from Distant Star

Posted on by Posted in Chapter 2 - Light as Particles, PMT/Scintillation Processor

Javier De Elias Cantalapiedra from Madrid, Spain posted the YouTube video above to show his very elegant experiment in which he measured Planck’s constant using photons from a distant star.  As in the e/m measurement he had previously shared with us, his experimental technique is very rigorous, which yielded Planck’s constant with just 5% error.  This is remarkable given the method he applied.

Javier is an industrial engineer who works in the telecommunications industry.  However, his passion is physics, which he pursues at a (very high) amateur level.

Thank you Javier for sharing!

Febetron/Fexitron Marx Bank Module

Posted on by Posted in High-Voltage Power Supply, Marx Generators

I have kept on making space in my lab for new projects, and came across 3 new-old-stock Marx generator modules that were made for the Fexitron and Febetron flash X-ray sources and electron accelerators. The Fexitron and Febetron devices were made in the 1970s by the Field Emission Corporation, a division of HP, which is now L-3 Pulse Sciences.

Each module contains two complete 30 kV Marx stages. In the Febetron/Fexitron pulsers, modules were stacked to form Marx generators of up to 2.3MV output. The spark gap distance is adjustable. These modules are designed for use under 20-70 psi air or nitrogen.

My intention was to build a 180 kV fast Marx with these, so I had reverse-engineered the schematic for these modules. I’m putting it here in case that someone is interested.

The following are interesting links related to Fexitron/Febetron units:

 

Wade Holcomb’s (W1GHU SK) “Try NMR with your old CW rig”

Posted on by Posted in Nuclear Magnetic Resonance NMR
Wade G Holcomb's NMR magnet www.diyPhysics.com

Wade G Holcomb’s diy NMR system. W1GHU became a Silent Key in 2015. Click on the picture for a full-resolution image

Many years ago I corresponded with Wade G Holcomb (W1GHU, SK 2009) about his home-brew NMR spectrometer and MRI experiments.  Going through my files I found the documents that he had sent me back then (1996), including a picture of his diy NMR setup with a big surplus magnet and a copy of the article “Try NMR with your old CW rig” which he had published in the Winter 1996 edition of Communications Quarterly.

I looked Wade up today, and found that he became a silent key in 2009.  His article is nowhere to be found on the internet, so I decided to scan it and make it available so this part of his legacy doesn’t get lost.

Click here for a scanned version of the paper (this is the best I got.  It’s a photocopy of the original that Wade sent to me).

Click here for an OCR version of the paper.

UPDATE 16 Oct 2020:

Peter Brown sent me an e-mail telling me:

“Thank you for scanning and placing on the web Wade’s article from Communications Quarterly on turning your HF rig into a spectrometer.
I was fortunate to have had Wade’s mentoring over the years for making RF tuned circuits for NMR systems.
I have attached a jpg of Wade’s obituary on the off chance you may want it.
He was very proud of that article. He first tried submission for it in “73”, and “CQ”, and I believe in “QST”. He said they sent him rejection letters because they felt it was beyond the scope of their readership, and then tried Communications Quarterly, in which it was accepted.
I joked with him that his next publication should be “Try ham radio with your NMR spectrometer”, to entice the NMR scientists world wide to be interested in ham radio.  He didn’t think my joke was as amusing as I thought it was.”

 

 

F. Alzofon’s 1994 experiments DO NOT prove his model of gravity

Posted on by Posted in Nuclear Magnetic Resonance NMR, Theoretical Physics, Uncategorized

NOTE:  A detailed critique with high-resolution figures is available in pdf format at: Prutchi Critique of Alzofon Gravity Control Experiments

Lately, most of my ham radio activity has been in the microwave bands, and I was thinking about developing a demonstration Electron Paramagnetic Resonance (EPR) apparatus to combine my amateur radio and experimental physics hobbies. The inspiration was a 1990s paper on building a Nuclear Magnetic Resonance (NMR) spectroscope using an amateur radio HF rig which was published in one of the ham radio magazines [Holcomb, 1996]. My idea was to come up with a modern version of the concept by performing Electron Paramagnetic Resonance (EPR) at the amateur microwave bands by taking advantage that low-cost SDR transmitter/receivers up to 6GHz, powerful large neodymium magnets, and affordable transistor-based amplifiers are now widely available.

EPR, also known as ESR (Electron Spin Resonance) is an analytical spectroscopy method for studying materials with unpaired electrons. EPR is conceptually similar to NMR, but it is electron spins that are excited instead of the spins of atomic nuclei.

I have the math in the pdf white paper, but putting it simply, the sample is placed under an external magnetic field with a strength measured in Tesla [T]. The resonant precession frequency for free electrons happens at approximately 28 GHz/T.

In EPR systems commonly used in chemistry analytical labs, using a magnet with a field strength of 0.335 T (3,350 Gauss), the EPR frequency for free electrons is thus around 9.4 GHz. ONLY at around one right frequency will electrons precess for a given magnetic field strength.

So, it was researching for the DIY EPR project that I landed on a YouTube interview with David Alzofon. In it he discussed his father’s work on “gravity control” through Dynamic Nuclear Orientation, which could be achieved by applying pulsed EPR on a high-purity aluminum sample.   I would usually not bite onto antigravity claims, but it intrigued me because of Dr. Fredrick Alzofon’s reported understanding of physics, and mainly by the claim that he had experimentally demonstrated his theory using a standard laboratory EPR system.

The interview was very interesting, so I purchased David Alzofon’s book “Gravity Control with Present Technology” and read it carefully. Dr. Alzofon’s gravity theory is very elegant. However, I’ve seen many beautiful, but wrong explanations of gravity before, so I looked forward to the claimed experimental proof. His claim of positive results from an experiment conducted in May of 1994 using a Chemistry Department’s EPR system looked promising, so as I was reading the book, I was already planning to design my EPR device to work within the 10 GHz amateur band (for which I have the necessary equipment with power capabilities of up to 10.5W) and to add a precision scale to try to replicate Dr. Alzofon’s results.

The experiment consisted of monitoring the weight of the sample using a precision scale connected to a computer while the microwave field was pulsed on for 6 ms, followed by a 6 ms off period, and on again for 6 ms. Recording and averaging by the computer was started 1 ms prior to the first microwave pulse, but in the first set of experiments the recording seems to have started 5-6 ms prior to the first pulse [Page 138].

The figure below shows my analysis of results from the best run of Alzofon’s first experiment. It’s easy to see that the measured weight loss correlates with the presumed delivery of microwaves into the EPR instrument’s cavity.

All was going well, until I saw the results of Experiment 3, Test 4, labeled “Control” [Page 157] which shows that the exact same “weight loss” results were obtained with the magnet off!

Based on Dr. Alzofon’s model, weight loss should not have occurred with the magnetic field OFF, since dynamic nuclear orientation couldn’t happen if the EPR resonance condition was not satisfied during the microwave ON periods!

To this effect, in the third paragraph of page 133 Alzofon writes:

“Could the weight alteration be caused by anything other than the configuration of the fields? … Microwaves alone would have no effect on weight, either.”

According to the book, Experiment 3 was conducted as a demonstration for a potential investor, and I can just imagine Dr. Alzofon and his colleagues playing their version of “Pay no attention to the man behind the curtain” trying to distract their guests when the AF2004 graph appeared on the screen.

The book provides the following explanation to accompany the AF2004 (Control) graph:

“The current supplying the electromagnet to produce a constant magnetic field was switched off for Test No. 4 in order to test the role of the constant magnetic field in the correlations noted above. There remained a weak residual magnetic field whose magnitude was not measured. The correlation between the microwave field intensity and weight increments is still present.

It is felt that a plausible explanation for this persistence is that the fractional alteration in resonant microwave frequency is equal to the fractional variation in the constant magnetic field. Since the resonant frequency is so large (about 9.5 GHz), the bandwidth must also be very large, corresponding to alterations in the magnetic field. Plot AF2004 illustrates the correlation observed.”

The “plausible explanation” doesn’t make any sense to me, since any residual remaining field would be significantly lower than the field strength necessary to satisfy the conditions for EPR at 9.5 GHz. This would be especially true for the type of EPR spectroscope used in Dr. Alzofon’s experiments, since these use a very narrow frequency band to be able to look at the fine differences in a sample’s electron g-factor.

Given that experiment AF2004 is labeled as “Control,” I believe that the proper way to use it would be to subtract AF2004 from AF2003. In the following I present an overlay of the AF2003 (magnetic field ON) and AF2004 (magnetic field OFF). I fail to see any difference between the two outside the noise limit of the system, so I have to conclude that there is absolutely no variation that could be legitimately attributed to a reduction in weight of the test sample.

Next during Experiment 3, both the constant magnetic field and the microwave field were switched off. The graph labeled AF2005 showed no significant variation in weight, just a low-level noise baseline. This confirms to me that something in the switching of the microwave source produced an artifact in the weight measurement system which was incorrectly attributed by Dr. Alzofon as a valid signal.

In conclusion, I believe that the graph of AF2004 (Control, with magnetic field turned OFF) completely invalidates the claim that Dr. Alzofon’s model has been “experimentally proven.”

In his book and interviews David Alzofon invokes the usual suppression conspiracies to explain the lack of interest by Academia, Industry, the Military, and even Hollywood in pursuing his father’s model. However, I believe that the actual reason is much more mundane – any physicist or engineer who saw AF2004 would have immediately realized that the experimental data shows absolutely no effect on the gravitational pull experienced by the sample.

I laud David Alzofon for his honesty in including the AF2004 graph, because it not only invalidates the alleged experimental demonstration of the effect, but actually provides negative evidence against it.

I tried contacting David Alzofon via email at gravity@gravitycontrol.io seeking comments regarding this matter, but received no response.

REFERENCES

Alzofon F, and Alzofon D, Gravity Control with Present Technology, CreateSpace Independent Publishing Platform, 2018.

Holcomb W., “Try NMR with your old CW rig”, Communications Quarterly, Winter 1996, 23-28, 1996.

Murakami A, Live Call with David Alzofon on Gravity Control, 2019-04-21, https://youtu.be/C5I0yOxUEeQ

A detailed critique with high-resolution figures is available in pdf format at: Prutchi Critique of Alzofon Gravity Control Experiments

Published data are NOT protected by copyright!

Posted on by Posted in Administrative

I was cleaning my desk today, and came across a folder containing correspondence about a legal threat that I received a few years ago from someone accusing me of copyright infringement.

The accusation was that I had used his published data in one of the figures in one of my books without his permission, and had thus violated his copyright.

For my figure, I had drawn a stylized graph which matched the data presented in his graph, but I didn’t copy his figure. He acknowledged the fact that I had “changed the colors and style,” but insisted that the fact that he had placed a copyright notice meant that the data were his, and that anyone publishing a graph that matched these data would be infringing on his copyright.

Although presenting and contrasting previously published data are the basis for academic discussion, which is why it didn’t even cross my mind that I would be doing something unethical or illegal by presenting my version of the graph, I wanted to make sure. Indeed, I was right – in the US, as in most parts of the world, ideas, procedures, and data that can be independently retrieved or replicated (i.e. which are not specific to the subjective viewpoint of their creators) are not subject to copyright.

I also checked with the European Copyright Code, which states that the following are not to be regarded as “expressions within the field of literature, art, or science” that can be protected by copyright:

  • Facts, discoveries, news, and data;
  • Ideas and theories;
  • Procedures, methods of operation, and mathematical concepts.

Furthermore, hearings regarding the US Database and Collections of Information Misappropriation Act of 2003 show that data are not protected under copyright. It is clearly stated that while certain databases may qualify for copyright protection if they exhibit some modicum of creativity in the selection, arrangement, or coordination of the data, in no case are the data themselves copyrightable.

Bobby Glushko, now the Head of the University of Toronto Scholarly Communications and Copyright Office wrote a very nice article about this very question while the Copyright Program Manager at the University of Michigan. The article is available online at:

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/83329/copyrightability_of_tables_charts_and_graphs.pdf

Based on the explanations in the article, even if I had taken each single point of data in his chart, and just because it took him effort to acquire these data, it doesn’t mean that the data are subject to copyright protection. This is because:

“Facts, data, and the representations of those facts and data are excellent examples of things that require much “sweat of the brow” to create, but yet still do not receive copyright protection.”

Please note that I’m not a lawyer, so don’t take any of the above as legal advise. However, I hope this will be a good starting point for anyone who is threatened by a bully with a false claim of misappropriation of intellectual property based on use of published data.

 

 

OT: EmotiGlass Project Submitted for The Hackaday Prize 2018

Posted on by Posted in Uncategorized

Jason Meyers and I submitted our project “EmotiGlass” as our entry in The Hackaday Prize 2018.

All augmented reality devices so far provide an interactive experience of the real-world environment that is enhanced by computer-generated perceptual information.  In contrast, the EmotiGlass project explores ways in which a computer can modulate the user’s EMOTIONAL perception of reality.  Our projects aims to develop the first “Modulated-Emotion Reality” device.  EmotiGlass enables completely new applications in the field of augmented reality in which emotional biases can be manipulated by computer applications. Additionally, EmotiGlass has potential therapeutic applications as an aid to help control stress and anxiety.

To demonstrate and develop the EmotiGlass concept, a wearable prototype was designed and constructed.  This open-source project was designed from the beginning to be easy to build using tools and materials widely available to makers and hobbyists.  Full design files and detailed build instructions are available at the hackaday.io project page so that anyone can reproduce or extend the EmotiGlass design.

NOTE: The potential therapeutic applications for EmotiGlass have not been reviewed by FDA or any other regulatory agency.

A complete whitepaper is available at: EmotiGlass – v4.1 PUBLISHED –

 

Converting a 1980s Video Camera into a Real-Time Polarimetric Imager

Posted on by Posted in Polarimetric Imaging

Real-time polarimetric imaging camera by David Prutchi Ph.D.

Three years ago I developed the DOLPi polarimetric cameras  based on the Raspberry Pi. One used an electro-optical polarization analyzer, while the other used discrete polarization filters mounted on a filter wheel. The only issue with their performance was lack of speed.  I mentioned back then that high-speed polarization imagers have been built using multiple sensors, each with its dedicated, fixed-state polarization analyzer.  I finally got around to converting a 1980s-era three-tube camera into a real-time polarimetric imager.  The full whitepaper with detailed step-by-step instructions is available for download in pdf format at:  Converting_the_JVC_KY-1900_into_a_Real-Time_Polarimetric_Imager_-_Prutchi_2018

Continue reading→

Rebuild of my diy Image Intensifier System for QP Experiments

Posted on by Posted in Chapter 2 - Light as Particles, Single-Photon Experiments, Single-Photon Imaging, Two-Slit Interference

After many years of use, the image intensifier tube (IIT) in the image intensifier system that I use for my experiments in quantum physics developed some nasty half-moon shadows in the periphery, so I decided to rebuild it with another MX-10160-type IIT.  I documented the build in the following document: diy Image Intensifier System Prutchi

Thermal Camera diy Macro and Telephoto Converters Posted to UVIRimaging.com

Posted on by Posted in Medium Wave Infrared Imaging, Thermal Camera

I recently purchased a Seek RevealPro Thermal Camera, which boasts a 320 x 240 thermal sensor with >15 Hz frame rate at an incredibly affordable price.

One of the only issues that I have with this camera is that it comes with a fixed 32° field-of-view lens. This is OK for general thermal inspection, but it’s a real disadvantage when trying to use the camera for close-up work to assess dissipation on printed circuit boards, or for identifying a faulty or undersized component. On the opposite side of the distance range, the 32° FOV lens makes it difficult to see and measure the temperature of objects at a distance, or of smaller objects at normal distances.

I thus decided to build magnifying (“macro”) and close-up (“telephoto”) converters for the RevealPro. I’m passing along information on my designs in hopes that others will find it useful.  Detailed instructions in the following whitepaper: Diy-Thermal-Camera-Telephoto-Converter

DOLPi Camera Wins Gadget Freak of the Year Award!

Posted on by Posted in Uncategorized

Gadget Freak of the Year AwardDavid Prutchi won Design News’ prestigious “Gadget Freak of the Year” award for his development of the DOLPi diy Polarimetric Cameras.

David will present the DOLPi project at MD&M West in February 2017. The award will be presented at the Golden Mousetrap Awards Ceremony during the show.

Design News’ Golden Mousetrap Awards are part of UBM’s broader Anaheim event, North America’s most comprehensive design and manufacturing tradeshow and conference. Comprised of six shows and interrelated conferences from the company’s portfolio, the event includes Automation Technology Expo (ATX) West, Electronics West, Medical Design & Manufacturing (MD&M) West, Pacific Design & Manufacturing, PLASTEC West, and WestPack, and attracts more than 20,000 attendees.