Irving H. Malitson

Interspecimen Comparison of the Refractive Index of Fused Silica

The index of refraction of optical quality fused silica (SiO2) was determined for 60 wavelengths from 0.21 to 3.71 μ at 20°C. The dispersion equation n2-1=0.6961663λ2λ2-(0.0684043)2+0.4079426λ2λ2-(0.1162414)2+0.8974794λ2λ2-(9.896161)2.where λ is expressed in microns was found to yield an absolute residual of 10.5×10−6. The variation in index between 12 specimens was determined. Dispersive properties of the material and thermal coefficient of index are graphically presented. A comparison with previous NBS index data is discussed.

Refraction and Dispersion of Synthetic Sapphire

The refractive indices of synthetic sapphire (Al2O3) were measured at selected wavelengths and the values of index range from 1.834 at 0.265 μ in the ultraviolet to 1.586 at 5.58 μ in the infrared. A three-term Sellmeier dispersion equation of the form n2-1=∑iAiλ2λ2-λt2was fitted to the experimental data. Dispersive quantities were computed which estimate the optical performance to be expected from sapphire.

A Redetermination of Some Optical Properties of Calcium Fluoride

This paper gives refractive-index values at 24°C for a synthetic and a natural prism of calcium fluoride. Measurements were made by the minimum-deviation method at 46 calibrated wavelengths from 0.23 μ in the ultraviolet to 9.7 μ in the infrared. The indices of the synthetic prism were fitted to a three-term Sellmeier dispersion formula of the form: n2 − 1 = ∑Ajλ2/(λ2 − λj2). Dispersive quantities were computed which estimate the expected relative dispersion, chromatic aberration, and resolution of CaF2 as a function of wavelength. Values of dn/dt are also given. The results of this work are compared with previously reported data.

Refractive Index of Arsenic Trisulfide

The refractive index of a sample of As2S3 was determined at three temperatures near 19°, 25°, and 31°C for selected wavelengths in the range 0.57 μ to 11.8 μ. A five term Sellmeier type dispersion equation was fitted to the averaged data reduced to 25°C; four of the constants were chosen to approximate an absorption continuum in the ultraviolet and visible while the fifth term was arbitrarily chosen as beyond the infrared absorption edge. The indexes of refraction in the visible region of two other samples were obtained for comparison.

Refractive Properties of Barium Fluoride

Refractive properties of barium fluoride are discussed. The refractive index, n, was determined at 25°C for 46 measured wavelengths from 0.2652 μ in the ultraviolet to 10.346 in the infrared. The dispersion equation n2−1=0.643356λ2λ2−(0.057789)2+0.506762λ2λ2−(0.10968)2+3.8261λ2λ2−(46.3864)2,where λ is expressed in microns was found to fit the measured values with an average absolute residual of 1.91×10−5. A tentative average thermal coefficient of index dn/dt for the measured spectral range is −12×10−6/°C Dispersive quantities which indicate the expected relative dispersion, chromatic aberration, and the effect of index on resolution are graphically presented. A review of transmittance data from the literature is also presented.

Refraction and Dispersion of Thallium Bromide Iodide

The refractive indexes of a mixed crystal containing 45.7 mole percent thallium bromide and 54.3 mole percent thallium iodide were measured at three temperatures near 19, 25, and 31°C for wavelengths from 0.5770 to 39.38 μ. The data were fitted to Sellmeier dispersion equations and thermal coefficients of index were computed. Dispersion coefficients were determined at 25°. The results were compared with data on a similar crystal.

A Special Method for Precise Refractive Index Measurement of Uniaxial Optical Media

A method was developed for measuring the refractive index of optical glasses and uniaxial crystalline solids when established refractometric methods are not feasible. A synthetic ruby cuboid was contacted to a prism of known refractive index and a spectrometer was used to measure the angles describing the optical path through the ruby-glass combination. Ray tracing equations were derived to compute the refractive index accurate within 3 x 10(-5). Index values for both polarizations of ruby are given at selected wavelengths from 0.4358 microm to 0.7065 microm.

Infrared Dispersion of Some Oxide Glasses

The refractive indices of silicate, germanate, calcium aluminate, and tellurite glasses have been determined in the wavelength range from about 0.4 μ to 5.3 μ. The experimental data for the silicate and germanate glasses were fitted to a Sellmeier dispersion equation of the form n2 = 1 + ∑Ajλ2/(λ2 − λj2). Dispersive curves were plotted which indicate the expected dispersion, contribution to chromatic aberration, and resolution of the glasses as a function of wavelength.

Survey Of Refractive Data On Materials For High-Power Ultraviolet Laser Applications

A literature survey of refractive indices, thermo-optic constants and photoelastic constants has been conducted for materials of potential use in high-power ultraviolet applications. The limiting ultraviolet wavelength for which data exist is given for twenty alkali-halides, sixteen other crystalline solids, and three glasses. The bulk of the materials selected for the survey have band gaps that exceed 7 eV which is twice the photon energy of the XeF laser. There are large gaps in the available data for most of the materials.