Partial Internal Reflection Research Articles

The use of the stationary phase method as a mathematical tool to determine the path of optical beams

We use the stationary phase method to determine the paths of optical beams that propagate through a dielectric block. In the presence of partial internal reflection, we recover the geometrical result obtained by using Snell's law. For total internal reflection, the stationary phase method overreaches Snell's law, predicting the Goos-Hänchen shift.

Analysis of Gibbs Monolayer Adsorbed at the Toluene/Water Interface by UV−Visible Partial Internal Reflection Spectrometry

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis(4-sulfonatopheny)porphyrin adsorbed at the liquid-liquid interface have been analyzed by UV-visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles (thetaERB and thetaIRB) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection-absorbance of UV-visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over thetaIRB. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid-solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.

Analysis by partial reflection spectrometry of protonated tetraphenylporphyrin adsorbed at a liquid-liquid interface.

Visible reflection spectra of diprotonated meso-tetraphenylporphyrin adsorbates spontaneously formed at a dodecane-aqueous sulfuric acid interface have been measured using a home-made device comprising a prism-cell and variable-angle optics. The tilt angle of the pyrrole ring plane was estimated to be 47 degrees from the interface normal by use of an experimentally evaluated molecular density (1.20x10(-10) mol cm(-2)) of the diprotonated molecule in a monolayer form at the liquid-liquid interface. Positive and negative bands have been observed in the p-polarized partial internal reflection (p-PIR) spectra, whose band locations correspond to those in p-polarized external reflection (p-ER) spectra. Nevertheless, the bands in the p-PIR exhibited reversed sign to those of p-ER spectra. These suggest that the surface selection rule of the p-PIR spectrometry has a reversal rule of p-ER and p-PIR can also be used for the analysis of molecular orientation.

Attenuated partial internal reflection infrared spectroscopy.

A new method for the spectroscopic study of absorbing films is proposed. In contrast to the well-established methods that take advantage of the attenuation of total internal reflection (ATR) to obtain spectra, we intentionally arrange the optics to permit partial internal reflection from the sampling prism face. Attenuated partial internal reflection (APR) spectroscopy is introduced through theoretical calculations and experimental demonstrations. The calculated APR spectra in the infrared region were generated from the Fresnel and Airy equations. Experimentally, APR spectra of water films on a NaCl prism were obtained. APR is more sensitive than ATR, and can easily distinguish water films at the monolayer level (310 pm). The determination of film thickness from interference fringes in APR spectra is also illustrated. It is shown that APR can be used for film thickness measurements that can span 6 orders of magnitude. The limitations of APR are also discussed.

Blue spot on the parhelic circle

We develop a theory for a new effect on the parhelic circle. We show that there is a colored segment on the parhelic circle at a certain large azimuth that depends on solar elevation. The color segment appears at solar elevations below 32 degrees and is explained as a transition between total and partial internal reflection in the main ray paths of the parhelic circle in oriented ice crystals. Based on our simple refraction theory and computer simulations, we find that the color of the segment is mainly green and blue. The theory is tested with available photographs of the effect.

Self-pumped phase conjugation in Bi 12 TiO 20 crystal without external cavity

We present an experimental study of the self-pumped phase-conjugate-mirror (SPPCM) recording in a Bi12TiO20 sample due to the partial internal reflection of the pump beam from the rear face. SPPCM has been recorded under an external alternating electric field of a square-wave form with response time equal to 170 s at the pump beam intensity of 520 mW/cm2. The mechanism of the SPPCM formation is similar to that of photorefractive double-phase-conjugate mirrors. The most effective SPPCM is recorded at the much larger pump-beam-incident angle than it could be supposed from the typical angular dependence of the two-wave-mixing gain factor. Strong dependence of the gain distribution on the pump-beam-propagation angle is observed. It is found that the response time strongly depends on the preliminary history of the sample.

Internal reflection beneath capillary water waves: a method for measuring wave slope

Ray-tracing simulations were performed to explore total internal reflection of light rays beneath capillary water waves. A vertically oriented light ray, scanned laterally below the wave surface, is mapped to a position that oscillates at a frequency f. It was found that f varies over 2 orders of magnitude as the dimensionless wave height a/lambda varies from 0.34 to 0.73. This presents a possible frequency domain method for wave slope measurement in wave tank experiments. A linear relationship between the maximum displacement of the mapped ray and a/lambda is also demonstrated for a/lambda between 0.54 and 0.73, presenting a second wave slope measurement approach. The consequences of partial internal reflection are considered.

On Certain “Ghost” Lines Observable with a Prism Spectrometer, and Their Use in Precision Refractometry

When a prism with three polished faces is used on a spectrometer, because of partial internal reflection, light eventually emerges from all three faces of the prism. It is shown that, in general, there are only two directions of emergence from each face. From the face of incidence one of these directions is uniquely that of the externally reflected light. The two emergent beams from any face are unequally dispersed, and in certain circumstances one may be undispersed (one of the beams from the face of incidence is always of this character). In such circumstances the undispersed beam coincides in direction with each component of the dispersed beam when that component is at minimum deviation. This property provides an accurate method of adjustment for minimum deviation. When this method is used in practice, there are important advantages to be gained by heavily silvering two of the prism faces and making observations on the spectrum observed in a telescope directed towards the unsilvered face of incidence.

LONG DISTANCE V.H.F. FIELDS: I. PARTIAL REFLECTION FROM A STANDARD ATMOSPHERE

Reliable propagation of V.H.F. waves and microwaves from high power transmitters to distances of several hundred miles beyond optical range has been demonstrated by an ever increasing number of experiments during the last ten years. The fields which have been observed have consistently been many times greater than the field strengths predicted by the "effective radius" theory. The present paper will be published in two parts. In Part I the theory that the phenomenon can be explained solely in terms of "partial internal reflection" from elementary layers of a dielectric distribution where the rate of decrease of (μ – 1) with height is everywhere continuous and of the same order of magnitude as in a "standard" atmosphere is carefully examined and found to be untenable. In Part II, the case where the distribution contains "sharp layers" (i.e., local regions where (μ – 1) changes relatively rapidly with height) is examined and it is found that these could cause the phenomenon. However, in view of the other characteristics of the observed field, it is concluded that the effect in question is probably more usually due to scattering of the electromagnetic waves from atmospheric turbulence.