Michael Hercher

Bio: Michael Hercher is an academic researcher from The Institute of Optics. The author has contributed to research in topics: Fabry–Pérot interferometer & Laser. The author has an hindex of 5, co-authored 8 publications receiving 344 citations.

The Spherical Mirror Fabry-Perot Interferometer

Abstract: The theory, design, and use of the confocal spherical mirror Fabry-Perot interferometer (FPS) is described in detail. Topics covered include performance of an FPS for small departures from the confocal mirror separation, optimization of the (resolution) x (light gathering power) product, factors limiting realizable finesse, mode matching considerations, alignment procedures, and general design considerations. Two specific instruments are described. One is a versatile spectrum analyzer with piezo-electric scanning; the other is a highly stable etalon with fixed spacing. Examples of the performance of these instruments are given.

Tunable single mode operation of gas lasers using intracavity tilted etalons.

Abstract: The use of a tilted solid etalon inside the resonator of a gas laser, for the purpose of obtaining a tunable single mode output from the laser, is described and analyzed. This technique is illustrated by single mode spectra and gain profiles obtained with various argon ion laser transitions.

Stable multipass Fabry-Perot interferometer: design and analysis.

Abstract: A multipass plane parallel Fabry-Perot interferometer (FPP-M) can give extremely high contrast (in excess of 106) over a wide range of finesse values without reducing the transmission significantly. Curves and tables are provided along with a brief outline of Chabbal’s analysis for the residual defects of the Fabry-Perot mirrors to aid a quick assessment of the optimum parameters for a desired spectrometric work. The exploitation of the advantages of an FPP-M depends upon the maintenance of its stability. So, we have constructed a passive interferometer of low thermal expansion material, Cer-Vit, along with nonkinematic design and thermally compensated mirror mounts to achieve long term stability without the use of a servo control device.

Relationship between the Near Field Characteristics of a Ruby Laser and Its Optical Quality

Abstract: It is shown, theoretically and experimentally, that there is a correspondence between the near field distribution of light from a ruby laser and its interferogram. Specifically, it is shown that, in general, filaments occur in ruby lasers but that these are not present for good quality crystals. An interferometric method for assessing crystal quality is described. The results of preliminary investigations of the spatial distribution of coherence in the near field of a good laser are given, and it is shown that there is a high degree of coherence between points separated by as much as 3.2 mm on the face of a ruby laser.

Method for obtaining gas concentration with a phase-based metrology system.

Abstract: A new technique is presented for obtaining gas concentration by measuring the slope of the anomalous dispersion at a resonance. We describe the equations that govern this process using a Lorentz model and show that the slope of the anomalous dispersion is directly related to the absorption coefficient. The slope is obtained from an interferometric setup and a frequency modulation spectroscopy technique. Experimental data are presented that illustrate this technique for two different sample cells containing water vapor.

Optical Detection of Ultrasound

Abstract: A review of the various optical methods to detect ultrasound (bulk and surface waves) at the surface of opaque solids is presented. The most useful techniques are thoroughly analyzed. Their performance when nonideal conditions are encountered, such as vibrations, air turbulence, and rough light scattering surfaces is evaluated. This review includes a description of knife-edge techniques, optical heterodyning, differential interferometry, and velocity (time-delay) interferometry methods, plus a mention of various less-important tech-

Optical parametric oscillator threshold and linewidth studies

Abstract: This paper presents a detailed study of the optimum design parameters for the LiNbO 3 parametric oscillator. Theoretical and experimental studies of the optical parametric oscillator (OPO) threshold parameters and of linewidth control are presented. Consideration is given to practical factors that limit OPO performance such as laser beam quality and crystal damage mechanisms. In addition, stable single axial mode operation is reported.

Observation of the resonant Stark effect at optical frequencies

Abstract: The spectrum of resonantly scattered light at right angles to a sodium atomic beam is reported. The light source was a cw dye laser tuned to resonance with a hyperfine component of the Dz line, and incident at right angles to the atomic beam. The spectrum, with the Stark effect sidebands, was recorded as a function of both the laser intensity and its detuning from resonance. The overall resolution is better than 20 MHz.

Advances in acoustic microscopy

Abstract: Characterization of Electronic Components by Acoustic Microscopy G. Pfannschmidt. Interaction of Acoustic Waves with Solid Surfaces Y. Tsukahara, et al. Scanning Acoustic Microscopy with Phase Contrast W. Grill, et al. Ultrasonic Focusing with Time Reversal Mirrors M. Fink, C. Prada.