F. V. Kowalski

Colorado School of Mines · Department of Physics

A two-body quantum correlation is calculated for a particle reflecting from a moving mirror. Correlated interference results when the incident and reflected particle substates and their associated mirror substates overlap. Using the Copenhagen interpretation of measurement, an asynchronous joint probability density (PDF), which is a function both o...

Most engineers and scientists would readily agree that the ability to ask and pursue productive questions can lead to a more globally competitive workforce; students with this ability can also enrich the STEM classroom learning environment. Through demonstration, active learning, and small group activities, this special session explores how we can...

This paper first provides an overview of the pedagogical role of formative assessment in the undergraduate engineering classroom. In the last decade, technology-facilitated implementation of the collection and analysis of student responses has reduced the clerical burden on educators, making the practice more widespread. We discuss some of the reas...

A two-body quantum correlation is calculated for a particle and an infinite potential well in which it is trapped or either a barrier or finite well over which it traverses. Correlated interference results when the incident and reflected particle substates and their associated well or barrier substates overlap. Measurement of the particle in this r...

A two-body quantum correlation is calculated for a particle reflecting from a mirror. The joint probability density, which is a function both of the different positions and different times at which the particle and mirror are measured, is derived assuming that no interaction occurs between the time each is measured. Correlated interference results...

One major puzzle of science today is why quantum effects are not apparent in our macroscopic world even though they are manifest microscopically. The quintessential example is double slit interference where the fringe spacing becomes imperceptibly small with increasing mass. However, reflection of a microscopic particle from a macroscopic `mirror'...

InkSurvey is a free, web-based software designed to facilitate the collection of real-time formative assessment. Using this tool, the instructor can embed formative assessment in the instruction process by posing an open-format question. Students equipped with pen-enabled mobile devices (tablet PCs, iPads, Android devices including some smartphones...

InkSurvey is free, web-based software designed to facilitate the collection of real-time formative assessment. Using this tool, the instructor can embed formative assessment in the instruction process by posing an open-format question. Students equipped with pen-enabled mobile devices are then actively engaged in their learning as they use digital...

There is general agreement that creativity and innovation are desirable traits in the toolbox of 21\textsuperscript{st} century engineers, as well as in the future workforce in general. However, there is a dearth of exemplars, pedagogical models, or best practices to be implemented in undergraduate engineering education to develop and nurture those...

This paper describes results from a project in an undergraduate engineering physics course that coupled classroom use of interactive computer simulations with the collection of real-time formative assessment using pen-enabled mobile technology. Interactive simulations (free or textbook-based) are widely used across the undergraduate science and eng...

Students' curiosity often seems nearly nonexistent in a lecture setting; we discuss a variety of possible reasons for this, but it is the instructor who typically poses questions while only a few students, usually the better ones, respond. As we have developed and implemented the use of InkSurvey to collect real-time formative assessment, we have d...

Increasingly affordable mobile computing devices can be used effectively to facilitate real-time formative assessment. Students equipped with pen-enabled Android devices, iPads, iPhones and/or tablet PCs can use digital ink to reveal their thinking as they construct new understandings of concepts. InkSurvey is free, web-based software (ticc.mines.e...

Creative thought and the ability to innovate are critical skills in industrial and academic careers alike. There exist attempts to foster creative skills in the business world, but little such work has been documented in a physics context. In particular, there are few tools available for those who want to assess the creativity of their physics stud...

An innovative pedagogical method of coupling interactive computer simulations (sims) with real-time formative assessment using pen-enabled mobile technology was used to improve learning gains in two core Chemical Engineering courses - Fluid Mechanics and Process Dynamics and Control. Students' understanding of concepts, calculations, etc. demonstra...

Moshinsky's problem is formulated and solved as a convolution integral. The initial data are discontinuous, giving the possibility of non-uniqueness. Asymptotic properties of the solution are deduced, using variants of the method of stationary phase. Comparisons are made with solutions of analogous problems for the one-dimensional wave equation and...

Solutions to the Schroedinger and Klein-Gordon equations for retroreflection of a nonzero-rest-mass particle from an accelerating mirror are determined using a retarded-phase method. The output of a Michelson interferometer, in which one mirror moves, reveals differences between the predictions of these two equations in the nonrelativistic limit wh...

We present a description and preliminary results of our use of Tablet PCs to strengthen problem-solving skills in an upper-level course. This design is a modification of well-established steps used to teach increased competency in problem-solving strategies in engineering courses. Novelly, however, these steps are facilitated by the use of Tablet P...

Worldwide, higher education instructors are exploring ways of enhancing classroom learning experiences with their Tablet PC-equipped students. To collect real-time formative assessment, instructors pose an open-format question to the class and the students utilize the digital ink of Tablet PCs to respond with answers in the form of handwriting, dia...

We report the spectral characteristics of a frequency-shifted feedback laser using a semiconductor optical amplifier as a gain medium in a free-space ring cavity configuration. Oscillation bandwidths as broad as 130 GHz have been measured. Using self-delayed heterodyne interferometric experiments, we confirm the generation of a comb of chirped freq...

This panel discussion will highlight emerging best practices in the use of Tablet PCs to transform learning and teaching in college and university engineering and computer science related courses. Faculty from four institutions will share their experience in redesigning a key course to improve student outcomes, and demonstrate how their innovative...

Generation of a chirped comb with chirp rate of 85PHz/s across 130GHz from a frequency-shifted feedback ring laser with semiconductor optical amplifier as gain medium is reported. Electronic tunability from 1535 to 1580nm was measured.

Diffraction from gratings moving at constant speed is calculated for electromagnetic, Klein-Gordon, and Schrodinger dispersion relations. Applicability of the results to relativistic and superluminal grating speeds is discussed. Negative total energy solutions for particles of non-zero rest mass are obtained along with static and near static inhomo...

We describe a unique K-14 outreach program of Colorado School of Mines, a public engineering university. This program is centered on Classroom Communication Systems (a.k.a. student response systems), in which every student uses a handheld, wireless IR remote device to transmit a response to a question posed by the instructor. The responses are reco...

The use of tablet computers for teaching and real-time assessment of conceptual understanding of engineering students is discussed. This progress can be divided into two main categories which include, one is content enhancement while the other is feedback on student understanding. The combination of student-directed content enhancement and real-tim...

Using frequency shifted feedback lasers, noise waveforms repetitive in phase but not amplitude are generated. The time correlation function is quasiperiodic, while the power spectrum is broadband and exhibits no structure. To illustrate potential applications of this source, a multiple access communication method is described in which the noise rep...

By use of frequency-shifted feedback lasers, noise with a stationary amplitude and a periodically stationary phase is generated. The ensemble-averaged time correlation function is periodic, whereas the power spectrum is broadband, resulting in a waveform that does not obey the Wiener–Khintchine relations. An application to multiple-access communica...

When modulated through the harmonic motion of one mirror, the counterpropagating waves in a ring laser oscillate out of phase. A solution to the wave equation is presented that satisfies both the time-dependent boundary condition and the resonance condition. This theoretical prediction is confirmed experimentally to leading order in terms that are...

The temporal behavior of a frequency shifted feedback laser is studied on a time scale comparable to the round trip transit time. Two possible models are considered: a continuous chirp or a discrete chirp which increases by the frequency shift each transit time. The consequences of these two predictions on heterodyne and homodyne experiments are an...

The properties of a frequency-shifted feedback (FSF) laser using a translated grating as the frequency-shifting element are investigated. FSF operation is attained by feedback of the first-order diffracted light from a grating coupler, which is translated in a direction perpendicular to the grating normal. A diode-pumped Nd:YVO4 gain medium is used...

The behavior of light clocks which undergo constant acceleration in flat space-time is considered. Time dilation, the Doppler shift, and clock synchronization are shown to be different from that of comoving unaccelerated clocks. These results are discussed in relation to the nature of time in accelerating systems.

A response is given to the work of Guangda et al. in which they criticize the paper ‘‘Phase Invariant Clock Hypothesis.’’ © 1996 The American Physical Society.

Using a transit-time technique, the phase difference is calculated for a neutron traversing an interferometer accelerating in flat space-time. The result differs from that calculated in a gravitational setting by an amount five orders of magnitude smaller than that resolvable by current experiment. However, when identical slabs of matter are insert...

Properties of lasers with frequency-shifted feedback are discussed. The analysis concentrates on the passive characteristics of the cavity. Particular emphasis is given to the case in which the frequency shift is small compared to the free spectral range of a normal Fabry-Perot cavity with no frequency shift.

The energy of a neutron propagating through a slab of material fixed in a gravitational fields is analyzed using the equivalence principle. Conservation of energy constrains the group transit time and/or the energy shift through the accelerating slab. This constraint is different from that predicted by an adiabatic approximation to the motion at co...

A method for calculating phase shifts in neutron interferometry which utilizes the transit time of the wavefunction is described. This method is used to determine the phase shift for neutrons interacting with moving matter and for neutrons traversing a rotating interferometer. In both these cases there has been some question about the correct use o...

The phase velocity of the free particle wavefunction is often presented as having two values, one associated with the relativistic expression for the energy and the other with the non-relativistic expression. The assumption is that the difference between these two is indistinguishable. It is shown that one of these phase velocities is inconsistent...

The effect of an intracavity accelerating dielectric on the frequencies of counterpropagating waves in a ring laser is calculated and measured. These circulating waves, which are neither harmonic nor propagating in a direction parallel to the motion of the dielectric, have their frequencies determined by the phase velocity in the dielectric. For a...

Experimental results are presented for a frequency shifted feedback dye laser for small shift frequencies. The laser system supports many frequency components simultaneously even though the gain medium is homogeneously broadened. The laser spectrum consists of a chirped comb of frequency components which, for low pump powers, are separated by the c...

A measurement of the phase of light reflecting from parallel mirrors which are fixed to a linearly accelerating platform is described. The angle of incidence of the beam on these mirrors is varied from 4° to 65°, and the acceleration is 0.05 m/s2. It is shown, for terms proportional to c−2, that the phase of the wave is independent of the accelerat...

We study spatially separated clocks that are Einstein synchronized in one inertial frame and then rigidly accelerated into another inertial frame. It is assumed that the clocks remain Einstein synchronized in the new frame in which they are now at rest. The consequences of this assumption are analyzed with respect to the experiments discussed in th...

The phase of an electromagnetic wave propagating through a dielectric, which is fixed in a gravitational field, is analyzed. This interaction results in a gravitationally dependent phase shift proportional to c-3. The size of this effect is briefly discussed with regard to a dielectric in Mach-Zehnder and Sagnac interferometers. The effect depends...

Frequency shifted feedback cavity (FSFC) lasers can generate continuous broadband radiation or periodic picosecond pulses. To better understand these two different regimes a passive FSFC is modeled and its output in the time and frequency domains is calculated. Calculations of the FSFC output indicate that peaks observed using a Fabry-Perot spectru...

A change in the RF frequency driving an acoustooptic modulator causes a change in the deflection of the diffracted light beam. It is found that for a certain angle of incidence upon multiple transducer acoustooptic modulators one can obtain diffracted beams which show no change in deflection for a change in acoustic frequency. However, the change i...

We present data on the optical response time of avalanche photodiodes as a function of the irradiance for two detectors: Newport model 877 and Antel model AR-S5.

A pulsed ring dye laser is constructed in which the light is shifted in frequency before being fed back into the gain medium. The active medium is R6G dye pumped by a continuous wave argon‐ion laser. An acousto‐optic modulator is used to shift the frequency of the light inside the ‘‘cavity.’’ With this device, we have generated optical pulses with...

A cw ring dye laser is constructed in which the light is shifted in frequency before being fed back into the gain medium. The active medium is R6G dye pumped by an argon-ion laser. An acousto-optic modulator is used to shift the frequency of the light inside the cavity. A continuous distribution of energy in a 0.75-nm bandwidth is observed in the o...

The behavior of the first-order diffracted beam of an acousto-optic modulator is investigated under rotation of the acousto-optic crystal about an axis perpendicular to the plane of the incident and diffracted beams. It is found that the diffraction efficiency as a function of this rotation is not symmetric about the Bragg angle of incidence. A uni...

A multipurpose optical-printhead evaluation device was designed that is capable of quantifying the performance of an optical printhead. A charge-coupled device (CCD) linear array measures the energy distribution produced by the printhead at the surface normally occupied by a photoconductive drum. From these measurements various mathematical entitie...

A train of pulses is generated by coupling the cw output of a single frequency He‐Ne laser into a passive ring ‘‘cavity’’ which contains an acousto‐optic frequency shifter. Each cavity pass shifts the frequency of the wave by 80 MHz. This results in an intensity pattern which is an Airy function in time. For a single frequency input, the output pul...

A new method for testing both refractive and reflective optical components using beam deflection is presented. For a beam with a 80-μm waist, 1-μrad deflections are detectable from a reflecting test surface. This corresponds to an average height resolution in the reflecting surface of eight-tenths of an angstrom over the dimensions of the beam.

We describe a new and highly effective optical frequency discriminator and laser stabilization system based on signals reflected from a stable Fabry-Perot reference interferometer. High sensitivity for detection of resonance information is achieved by optical heterodyne detection with sidebands produced by rf phase modulation. Physical, optical, an...

We analyze the excitation by an electromagnetic wave of a two-level molecule (or atom) within a rarefied gas. This process differs from the excitation of an isolated molecule because there is significant interaction between the molecule and the surrounding gas particles as they are all polarized by the electromagnetic wave. These interactions lead...

Wave-number measurements were made on 10 uranium and 2 thorium transitions using the optogalvanic effect in a hollow-cathode discharge to position a single-frequency, cw dye laser to the peak of a transition. The wave number of the dye laser was measured by comparing it with the wave number of an iodine-stabilized He-Ne laser. The accuracy of the w...

A new method of stabilizing the output frequency of a He–Ne laser in a longitudinal magnetic field has been developed. With simple modifications to a standard He–Ne laser tube we obtain a frequency stability of <1 MHz (<10⁻⁹) for an averaging time of 1 sec and a long term (5 months) frequency reproducibility of ~±1 MHz.

A new method of stabilizing the output frequency of a He--Ne laser in a longitudinal magnetic field has been developed. With simple modifications to a standard He--Ne laser tube we obtain a frequency stability of <1 MHz (<10/sup -9/) for an averaging time of 1 sec and a long term (5 months) frequency reproducibility of approx. +- 1 MHz.

A new method of stabilizing the output frequency of a He-Ne laser in a longitudinal magnetic field has been developed. With simple modifications to a standard He-Ne laser tube we obtain a frequency stability of <1 MHz (<10(-9)) for an averaging time of 1 sec and a long term (5 months) frequency reproducibility of ~ +/-1 MHz.

In two-step polarization labeling, as in polarization labeling, a polarized pump laser is tuned to a molecular transition. This produces an optical anisotropy in the upper and lower levels of the pump transition. A linearly polarized probe laser will experience a change in polarization when it interacts with these oriented levels of the molecule. P...

We describe a precision interferometer calibration technique useful for the measurement of the wavelength of atomic and molecular transitions with megahertz accuracy. Using this technique, the wavenumber of the ith hyperfine component of the ¹²⁷I2 B-X R(73) 5-5 transition, which falls within the Doppler width of the hydrogen Balmer-α line, has been...

We report on a modified version of our previous moving mirror wavelength measuring interferometer. Its accuracy has been experimentally confirmed to one part in 108. The device is simple and seems ideally suited for cw lasers.

The background in saturation spectroscopy is decreased by balancing the probe beam, in amplitude and phase, against a second probe, using a configuration like a Jamin interferometer. This improves the signal-to-noise ratio. If the phase is adjustable to provide best balance while the laser is tuned, the signal is proportional to the square of the a...

We have used two-photon absorption from counterpropagating laser beams of different frequencies to measure Stark shifts and splittings of the 62S, 72S, 82S, 52D, and 62D states in sodium. Beams from a fixed-frequency, single-mode Ar+ laser and a tunable, single-frequency cw dye laser were focussed into a coarse sodium atomic beam and the fluorescen...

The wavelength of light can be measured by counting the number of fringes as an interferometer mirror is moved through a known distance. The known distance is best obtained by simultaneously counting the number of fringes from a standard wavelength source for the same change of optical path length. The arrangement in Fig. 1 permits rapid and precis...

Polarization spectroscopy makes use of the polarization dependence of the nonlinear interaction between two laser beams in a gaseous medium. The laser-induced optical anisotropy is calculated using a rate equation approach, and the effect of this anisotropy on a polarized probe beam is derived. The method is useful for Doppler-free spectroscopy, fo...

The ratio of an unknown laser wavelength to that of a standard is quickly determined by a two-beam interferometer with a corner-cube reflector moving on an air track. Standard and unknown wavelength beams travel identical paths in opposite directions, so refractive index corrections are minimized. Accuracy is about six parts in 108. Absolute measur...

Molecular absorption lines from a common lower level are intensity modulated by chopped-laser saturation of another line from that level. Populations of some other levels are also modulated by subsequent fluorescence. Both types of modulated lines are free of Doppler broadening. Also, collisional depopulation modulates absorption from rotational le...