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Department Library

2019

Jarom Silver Jackson (PhD Dissertation, June 2019, Advisor: Dallin Durfee )

Abstract

A method of lensless, single pixel imaging is presented. This method, referred to as MAS-IPSII, is theoretically capable of resolutions as small as one quarter of the wavelength of the imaging light. The resolution is not limited by the aperture of any optic, making high resolutions (including subwavelength) feasible even at very large (greater than a meter) distances. Imaging requires only flat optics and a coherent source, making it a good candidate for imaging with extreme wavelengths in the UV and x-ray regimes. The method is demonstrated by the imaging of various test targets. Both real and complex imaging (i.e. holography) is demonstrated.

Paige Price (Capstone, April 2019, Advisor: Dallin Durfee )

Abstract

External cavity diode lasers can mode hop unexpectedly. Based on previous measurements by others in the field, we have theorized that a substantial amount of phase noise occurs when a laser is about to switch modes. By monitoring this phase noise and making necessary adjustments, laser stability could possibly be maintained. We have developed an experiment to measure the phase noise to test our theory and determine the feasibility of this stabilization technique. However, the first step in this process is locking the laser to a reference cavity. The locking system currently being used does not work. This paper outlines the current progress and the steps that will be needed to finish testing whether phase noise increases before a mode hop.

2018

Ethan Welch (Senior Thesis, April 2018, Advisor: Dallin Durfee )

Abstract

I seek to make injection locking a more reliable tool in atomic physics by active stabilization. An injection-locked diode laser can be actively stabilized by monitoring either the laser's frequency spectrum or the overall intensity. I used the transmission of a Fabry-Perot cavity to measure the frequency spectrum of an injection-locked laser. When the injection lock is about to break, the intensity of the dominant spectral mode decreases while the overall intensity increases. Similarly, a photodiode measures the overall intensity of the laser. Under certain conditions, the injection-locked laser's intensity corresponds to how strong the injection-lock is. To prevent the injection-lock from breaking, an Arduino Uno measures either the amplitude of the main spectral peak or the overall intensity while simultaneously adjusting the current of the injection-locked laser. By so doing, an injection-lock that has an average lifetime of a few minutes can be stabilized to have a lifetime of several hours.

2017

John Chorak (Senior Thesis, August 2017, Advisor: Dallin Durfee )

Abstract

Previous work by T. Jones, et al., showed that a TCS3414 color sensor could be used to measure the wavelength of a laser accurate to within 10 picometers. This paper explores the potential of a webcam, specifically the Raspberry Pi Camera Module 2, to measure laser wavelength by using a larger array of photodiodes, which unlike those in the TCS3414, have not been averaged together. This is predicted to increase both etalon effects and achievable precision.

2016

Jarom Silver Jackson (Masters Thesis, June 2016, Advisor: Dallin Durfee )

Abstract

We present a novel method of in situ magnetic field mapping related to the Hanle effect. This method uses the change in spatial radiation pattern of scattered light, which we call a 'directional Hanle effect,' rather than the loss of polarization more commonly associated with the Hanle effect. It is particularly well suited for fields in a magneto-optical trap (MOT), requiring only the addition of a narrow slit and a camera to typical MOT components. The use of this method is demonstrated by measuring the gradient through, and location of, the zero-point of the field in our strontium MOT.

McKinley Pugh (Senior Thesis, April 2016, Advisor: Dallin Durfee )

Abstract

Extended cavity diode lasers (ECDLs) have a number of useful applications, but they mode hop. We have observed an increase in frequency noise before mode hops in ECDLs. A feedback system using frequency noise instead of amplitude noise has been developed

2015

Lawrence Archibald (Masters Thesis, December 2015, Advisor: Dallin Durfee )

Abstract

This work reports on the construction of a 408 nm laser system designed to drive stimulated Raman transitions between the F = 4 and F = 5 2 S 1/2 states of 87 Sr + using the 2 P 3/2 state as the intermediate state. This laser system will be used as part of a 87 Sr + ion interferometer. This work also includes a discussion of relevant theory describing the interaction of the ions and laser, along with a calculation of the transition rates as a function of laser power and detuning.

Cassi Burton (Capstone, September 2015, Advisor: Dallin Durfee )

Abstract

In music, consonance is the quality of sound sought after by musicians to create pure-sounding, pleasant music. The governing laws of physics behind consonance dictate that a guitar cannot have perfect consonance across all chords. To make all chords reasonably consonant, the equal temperament scale is accepted as the standard tuning scheme today. Its downfall is that it does not provide the best possible consonance in any one song. Since a song is comprised of only a few chords, creating consonance across all chords is not necessary—only across the chords being used in a song. With physics, we can calculate the frequencies to which each of the strings on a guitar should be tuned in order to optimize consonance across any set of chords. This report discusses the calculation used to optimize consonance and the Android app that I’ve developed to perform that calculation.

Tyler Jones (Senior Thesis, April 2015, Advisor: Dallin Durfee )

Abstract

One type of color sensor made for consumer electronics uses an array of optically filtered photodiodes. The filters cause the photodiodes' measurements to depend on the wavelength and the intensity of the incident light. The relative amounts of light measured by each photodiode can then be used to determine the light's color. These sensors are made for use with broadband light, but the data sheet for one such sensor, the TCS3414, lists very few limitations on its capabilities, indicating that the sensor may be useful in laser spectroscopy. This document explores the TCS3414's performance in laser spectroscopy. Considerations such as algorithmic method, intensity, bit noise, and temperature dependence will be discussed. Measurements show that the sensor's measurements are repeatable and accurate to within less than 10 picometers for time scales on the order of a day. While this is not precise enough to directly find atomic transitions, it is precise enough to get the laser close enough to the transition that it can then be scanned to find the transition without mode hopping. It is also comparable to many mid-grade interferometers. Therefore, the sensor is viable as an alternative method for measuring laser wavelength for short time scales.

Adam Kingsley (Senior Thesis, December 2015, Advisor: Dallin Durfee )

Abstract

Using the classical Hanbury Brown and Twiss effect, students will measure correlation at two detectors in order to discover the diameter of an aperture. The light source will consist of a laser, spatially modulated so that the effect can still be observed and measurements can easily be made. The students will gain an increased understanding of angular size, spatial coherence, interference, and the Rayleigh criterion.

Nils Otterstrom (Senior Thesis, April 2015, Advisor: Dallin Durfee )

Abstract

Many physics laboratories rely on accurate wavelength meters for metrology applications. Unfortunately, traditional instruments for laser spectroscopy tend to be expensive and fragile. We demonstrate a method for laser wavelength metrology using a simple and inexpensive color sensor made of an array of filtered photodiodes. The photocurrents from photodiodes under four colors of filters are measured digitally using an external microprocessor. With this data, we calculate the wavelength of a laser using a set of calibrated spectral response curves and a least squares error algorithm. After analyzing and controlling thin film interference effects in the sensor, we report an accuracy of 0.0053 nm (on the range of 460.79 nm to 460.89 nm) and a stability of 0.0039 nm over 41.5 hours (at 460.85 nm).

2014

Enoch Lambert (Senior Thesis, April 2014, Advisor: Dallin Durfee )

Abstract

Extended-cavity diode lasers (ECDL's) are an important tool in atomic, molecular, and optical physics. Preventing ECDL's from mode-hopping can enable further advances in these fields. The research described in this paper seeks improvements in the frequency stability of a diode laser by using feedback techniques. The diode laser is locked to a frequency reference, in this case a simple optical cavity. Radio-frequency (RF) noise is measured at various points in the combined laser-cavity system and used to generate an additional feedback signal to help control the laser. The added feedback system improved the laser's stability range by a factor of three when the laser was scanned.

2013

Jeffery Anderson (Capstone, June 2013, Advisor: Dallin Durfee )

Abstract

Jarom Jackson (Senior Thesis, April 2013, Advisor: Dallin Durfee )

Abstract

This thesis describes the work done to set up two external cavity diode lasers to be used in an ion interferometer. These lasers will be used to trap and cool atoms and to manipulate and probe their energy states. The main cooling laser is generated using a doubled IR laser, but is very unstable due to the various stages—diode, external cavity, doubling crystal and cavity—that all need feedback to lock the frequency. The probe laser is much simpler because the wavelength needed matches that of a readily available laser diode. The stability and scanning ranges of both lasers are presented.

2012

Mark Cunningham (Senior Thesis, August 2012, Advisor: Dallin Durfee )

Abstract

Michael Hermansen (Capstone, April 2012, Advisor: Dallin Durfee )

Abstract

I built a piezoelectric amplifier for a laser system used in a matter-wave interferometer. The piezoelectric driver is an essential part of each laser feedback system that controls the lock of each laser in the matter-wave interferometer. The lasers that we are building require extremely stable laser locks, therefore the piezoelectric amplifier I built must also be very quiet. I built this piezoelectric driver to be a lot less expensive and quieter than commercial units.

2011

Christopher Joseph Erickson (PhD Dissertation, December 2011, Advisor: Dallin Durfee )

Abstract

I present the construction of a low-velocity intense source (LVIS) of laser-cooled neutral strontium using permanent ring magnets. The LVIS consists of a magneto-optical trap from which cold strontium is extracted in a well-collimated beam. I also present the development and implementation of a full suite of low-noise, high-bandwidth laser control electronics including a microcontroller unit. This microcontroller remotely controls and monitors the current driver, temperature controller, and PID lock circuit for each diode laser simultaneously. The current driver output is accurate to within 2 µA and repeatable to with a few nA. The noise spectral density of the current driver hits a floor of 10−10 A/√ Hz at ∼ 50 Hz and has a modulation bandwidth of ∼ 50 MHz. The PID lock-circuit includes a scan-balancing option that we have used to scan an AR coated laser diode ∼ 30 GHz mode-hop free. I describe the construction of an 80 mW frequency doubled 461 nm laser system using PPKTP for cooling and trapping neutral strontium in the LVIS. The LVIS, the electronics systems, and the 461 nm laser system represent major milestones on the way to producing a matter-wave interferometer using 87Sr ions. The interferometer is based on an optical Raman transition between the hyperfine ground states of 87Sr+. The ions will be produced by exciting the strontium LVIS beam to an auto-ionizing state in the continuum. In the interferometer two π/2 pulses of light and one π pulse will be delivered to the ions to split and recombine their wave functions. I present calculations of the predicted sensitivity and a discussion of the possible applications. I present a method for locking a 407.8 nm laser to the 5s 2S1/2 to 5p 2P3/2 strontium ion transition in a neutral vapor. I present calculations for the necessary vacuum levels for the experiment and describe the preparation and assembly of the vacuum apparatus. The major vacuum system consists of two connected elastomer sealed chambers: one at 10−7 Torr and the other at 10−10 Torr separated by a region of low conductance. I present a Sr vapor cell constructed from standard CF fittings that allows the strontium to be heated to ∼ 730◦ C, which can also be run as a thermal beam. I present a method for protecting the viewports on small-form alkali-earth vapor cells using lead or indium foil during the evaporation of oxide layers. Finally, I report on the current status of the experiment as well as detail future work on the apparatus.

2010

Aaron Bennett (Senior Thesis, August 2010, Advisor: Dallin Durfee )

Abstract

I discuss a high speed, low noise homodyne photo-detector. This detector will be used to better implement laser locking techniques such as the Pound Drever Hall method or saturated absorption with lock-in amplification. I present a basic explanation of these methods and their benefits. I discuss aspects of the detector which allow it to operate with low noise over a high bandwidth.

Daylin Troxel (Senior Thesis, August 2010, Advisor: Dallin Durfee )

Abstract

Our lab designed special low-noise electronics in order to stabilize lasers for use in our atom and ion interferometers. The current driver was based on the Hall-Libbrecht design but included updated components, extra filters, and digital control. My work focused on characterizing the noise spectrum of our electronics. In this thesis I give an overview of noise measurements in general and present the procedure I used to measure the noise and the results of the measurement for the current driver and PID controller. I also characterize the measurement noise floor and the PID controller bandwidth.

2009

James Archibald (Senior Thesis, August 2009, Advisor: Dallin Durfee )

Abstract

We discuss work towards construction of a neutral-Ca atom interferometer. One component of this system is a frequency-doubled laser. We present an introduction to the concepts of second-harmonic generation that is intended to be accessible. We discuss various calculations related to the construction of the system.

Daniel Merrill (Senior Thesis, August 2009, Advisor: Dallin Durfee )

Abstract

I discuss a 657 nm, high stability, high power diode laser realized by injection locking a high power slave diode laser to an ultra-stable external cavity master diode laser. This laser system will be used in a thermal beam calcium atom interferometer. A method is also discussed for determining the linewidth broadening between master and slave lasers. The master laser beam is beat with the slave laser beam whose frequency is shifted by 200 MHz. The measured broadening between master and slave lasers was less than the 30 Hz resolution of our RF spectrum analyzer.

2007

Jeremiah Birrell (Senior Thesis, December 2007, Advisor: Dallin Durfee )

Abstract

In this thesis I determine the optimal parameters for maximizing second harmonic generation of 423 nm light for use in an atom interferometer. The analysis is done using the nonlinear crystal Beta Barium Borate. Both critical and noncritical phase matching methods are considered. The optimal beam size for a Gaussian beam profile is calculated. Build-up cavity design is analyzed in order to maximize the intensity in the crystal. An optimal setup, one that maximizes the output power of the 423 nm beam, is proposed.

Daniel Christensen (Senior Thesis, August 2007, Advisor: Dallin Durfee )

Abstract

This thesis presents two projects connected by a similar element of atom interferometry. First I describe the development of a stable and high-flux thermal atom-beam source to be used in an improved atomic time standard. Preliminary measurements have shown that this source produces an atomic beam with a flux >= 3.422 × 10^12 atoms per second with a most probable velocity of 750m/s. Then I present calculations verifying the feasibility of a proposed ion interferometer capable of setting a new lower limit on the mass of a photon. Our group’s initial model assumed an ion interferometer inside an infinite cylinder with no fringing fields. The calculations I present show that the infinite cylinder assumption is a viable approximation and that the classical fringing fields are negligible.

Christopher Joseph Erickson (Masters Thesis, November 2007, Advisor: Dallin Durfee )

Abstract

I describe the construction of a calcium matter-wave interferometer. The interferometer is based on a Ramsey-Bord´e scheme, and uses a thermal beam of atoms excited by an optical-frequency transition in calcium. In our experiment four π 2 pulses of light are delivered to the atoms, which split and recombine the wave functions of the atoms. Our experimental design minimizes first-order Doppler shifts, and allows for the cancellation of systematic errors including phase shifts due to rotation and acceleration. I describe the individual components of the interferometer and its assembly. The requirements for the electronics used in the experiment as well as their design and performance are described in great detail. I also give an overview of the techniques used to passively stabilize the laser and optical components. Finally, I report on the current status of the experiment as well as detail future work to be done on the apparatus.

Marshall van Zijll (Senior Thesis, April 2007, Advisor: Dallin Durfee )

Abstract

I created a digital potentiometer to be used for the stable control of the current in a laser current controller. This digital potentiometer consists of a microcontroller used in conjunction with a digital to analog converter (DAC). I selected a DAC that is appropriate for our design, I programmed a micro- controller to manage the DAC, and I designed the digital circuit board for the microcontroller. Our digital potentiometer is more stable, more accurate, has better repeatability, and picks up considerably less noise than a manual potentiometer.

2006

Greg Doermann (Senior Thesis, August 2006, Advisor: Dallin Durfee )

Abstract

n/a

Brian Neyenhuis (Senior Thesis, April 2006, Advisor: Dallin Durfee )

Abstract

I am designing a narrow linewidth 657 nm diode laser for use in an atom interferometer. I will discuss both passive and active stabilization of diode lasers as well as a new grating stabilization scheme developed in our lab with its advantages and disadvantages. I have constructed a high speed lock circuit with a bandwidth of 4 MHz that is used with the Pound Drever-Hall method to lock the diode laser to a cavity with a ¯nesse of 30,000. The laser's current linewidth is approximately 3 kHz.Future work and a plan to achieve a Hz level linewidth are presented

Justin Paul (Senior Thesis, August 2006, Advisor: Dallin Durfee )

Abstract

n/a

2005

Christopher Erickson (Senior Thesis, June 2005, Advisor: Dallin Durfee )

Abstract

n/a

2004

Rebecca Olson (Senior Thesis, January 2004, Advisor: Dallin Durfee )

Abstract

2003

Rebecca Merrill (Honors Thesis, March 2003, Advisor: Dallin Durfee )

Abstract