Minimum Deviation Technique Research Articles

NaBa12(BO3)7F4 (NBBF) dichroic crystals: optical properties and dielectric permittivity.

Three NaBa12(BO3)7F4 crystals were grown in the BaO-BaF2-B2O3-Na2O system from three different compositions of high-temperature solution. With the use of optical spectroscopy, energy-dispersive X-ray spectroscopy, and the Schering bridge method it was found that the crystals revealed sharp differences in their optical and dielectric properties. The relative permittivity of the crystals in direction perpendicular to the optical axis reached 319(5). The minimum deviation technique was used for refractive index measurements.

A dynamic goniometer-spectrometer with angle-to-time conversion

We present a dynamic goniometer–spectrometer for measuring the refractive index (RI) of transparent triangular prisms by converting the beam deviation angles into time intervals. The proposed measuring scheme allows the automatic determination of the RI simultaneously for several different wavelengths by measuring the time intervals between the moments of autocollimation of the reference and refracted rays reflected from a mirror continuously rotating around the object with constant angular speed. This makes it possible to avoid the use of an expensive ring laser or encoder for angle measurements and to use relatively inexpensive instruments for time measurements, which reduces the cost of measuring equipment. To calculate the RI value, we used the minimum deviation technique. A functional diagram of the measuring equipment is given. A reference prism made of NBK-7 Schott optical glass was experimentally studied and the measurement errors were estimated. The proposed measuring scheme can be used for automated RI measurement and to study the dispersion characteristics of triangular prisms made of optically transparent materials and liquid optically transparent substances filling a hollow triangular prism.

The modified minimum deviation method for measuring the refractive index

We present a modified method for measuring the refractive index (RI) based on the minimum deviation technique, which allows us to determine the RI of transparent triangular prisms with unknown apex angles. In the proposed method, the angles of light deviation are measured on three faces of the prism, and RI of the material and prism angles are determined from the solution of a system of equations. A high precision dynamic goniometer was used to implement the proposed method. A set of reference prisms made of optical glass were experimentally studied and the measurement errors were estimated. It is shown that the modified method can be used for high-precision measurements of the RI in cases when the prism angles are unknown, or their measurement is associated with technical difficulties. The method of measuring RI proposed in the article was implemented using the State Primary Standard of the Refractive Index Unit GET 138–2021 of the All-Russian Research Institute for Optical and Physical Measurements. This standard is intended for storing, reproducing, and transmitting the unit size of the RI of solid and liquid substances.

A high precision VIS/NIR dynamic goniometer-spectrometer

We present a method for measuring the refractive index (RI) and spectral characteristics of transparent triangular prisms based on the minimum deviation technique. The proposed method has been developed to automatically measure RI simultaneously for three different wavelengths to determine the spectral dependence of RI. A high precision dynamic goniometer with a He-Ne ring laser and continuously rotating autocollimation mirror was used to implement the proposed method. A set of reference prisms made of optical glass were experimentally studied and the measurement uncertainty budget was estimated. The obtained values of the expanded measurement uncertainty did not exceed 4.6 × 10−6 for near-infrared and 1.2 × 10−5 for visible wavelength ranges with a coverage factor k = 2 (95% level of confidence). It is shown that this method can be used for high-precision measurements of the RI and determine the spectral characteristics.

Crystal Growth and Optical Properties of Beryllium-Free Nonlinear Optical Crystal K3Ba3Li2Al4B6O20F

A beryllium-free nonlinear optical (NLO) crystal K3Ba3Li2Al4B6O20F (KBLABF) with sizes up to 18 × 13 × 8 mm3 was successfully grown by the top-seeded solution growth method using LiOH-H3BO3–BaF2 flux. The key limiting factors on the crystal morphologies and sizes were carefully analyzed. Meanwhile, by using the minimum deviation technique, the refractive index dispersion was measured and fitted well by the Sellmeier equations. The results suggest that KBLABF is a negative uniaxial crystal with moderate birefringence of 0.06050–0.06834 at a wavelength range from 363 to 852.1 nm. Furthermore, the type-I phase matching range for fundamental (second harmonic) light is down to 486 (243 nm) in theory, which indicates that KBLABF crystal could achieve 532 and 266 nm light generation by direct second-harmonic generation. As compared with the famous NLO crystals β-BaB2O4 and CsLiB6O10, KBLABF crystal exhibits a smaller walk-off angle and larger acceptance angle at the wavelength of 532 nm while having a comparable...

Large Birefringent Materials, Na6Te4W6O29 and Na2TeW2O9: Synthesis, Structure, Crystal Growth, and Characterization

A new d0 transition metal tellurite, Na6Te4W6O29, was synthesized by solid-state methods. The material crystallizes in monoclinic space group P21/c (No. 14) with the following values: a = 7.3297(3) A, b = 21.9057(9) A, c = 10.2871(3) A, β = 133.490(2)°, and Z = 2. Additionally, large crystals of Na6Te4W6O29 (13 mm × 11 mm × 10 mm) and Na2TeW2O9 (23 mm × 5 mm × 3 mm) were grown by the top seeded solution growth method. In addition to the crystal growth, refractive indices were measured, and the Sellmeier equations were fitted by using the minimum deviation technique. Interestingly, the two reported compounds exhibit relatively large birefringences: Δn3 = nz – nx = 0.0828–0.1248 from 1062.6 to 450.2 nm for Na6Te4W6O29, and Δn3 = nz – nx = 0.1471–0.2069 from 1062.6 to 450.2 nm for Na2TeW2O9. The results indicate that Na6Te4W6O29 and Na2TeW2O9 may have uses in applications involving birefrigent materials.

Application of the Minimum Deviation Technique to Liquid Concentration Measurements

Application of the Minimum Deviation Technique to Liquid Concentration Measurements

Linear and Nonlinear Optical Properties of K3B6O10Br Single Crystal: Experiment and Calculation

The experimental and theoretical analysis of linear and nonlinear optical properties of K3B6O10Br (KBOB), with a moderate birefringence that is suitable for UV coherent light generation and optical parametric oscillators, is presented in detail. The second-order nonlinear optical coefficients were measured by the Maker fringe method and the refractive indices dispersion curves were deduced by the minimum deviation technique at 16 different monochromatic sources from UV to NIR, and then the type I and type II phase-matching curves of second, third, and fourth harmonic generation (SHG, THG, and FHG) were calculated. Moreover, the correlations of crystallographic and crystallophysical axes were determined. On the basis of the density functional theory (DFT), the first-principles calculations have been employed successfully to study the structural and electronic properties of KBOB. In addition, to gain further insight into the structure-property relationship, the SHG density method was adopted to analyze the origin of the nonlinear optical response of KBOB.

New Nonlinear Optical Crystal: NaBa4Al2B8O18Cl3

Single crystals of NaBa(4)Al(2)B(8)O(18)Cl(3) have been grown with sizes up to 34 × 34 × 16 mm(3) from the NaF-LiCl flux by the top-seeded solution growth method. The compound crystallizes in the tetragonal system, space group P4(2)nm, with a = 12.0480 (16) Å, c = 6.8165 (11) Å, α = β = γ = 90°, and two formula units per cell. The NaBa(4)Al(2)B(8)O(18)Cl(3) compound is built up of infinite anionic groups of [AlB(4)O(12)](9-) formed by two BO(4) tetrahedra, one AlO(4) tetrahedra, and two BO(3) triangles. Optical properties including ultraviolet transmission, IR spectrum, and second-harmonic generation of NaBa(4)Al(2)B(8)O(18)Cl(3) crystals were reported. Refractive indices were measured by the minimum deviation technique and fitted to the Sellmeier equations. Thermal properties such as the DSC and thermal expansion were reported. The mechanical properties including the hardness, density, and chemical stability were also reported.

Refractive index of sodium iodide

The refractive index of sodium iodide, an important scintillator material that is widely used for radiation detection, is based on a single measurement made by Spangenberg at one wavelength using the index-matching liquid immersion method (Z. Kristallogr. 57, 494 (1923)). In the present paper, we present new results for the refractive index of sodium iodide as measured by the minimum deviation technique at six wavelengths between 436 nm (n = 1.839 ± 0.002) and 633 nm (n = 1.786 ± 0.002). These six measurements can be fit to a Sellmeier model, resulting in a χ2 of 1.02, indicating a good fit to the data. In addition, we report on ellipsometry measurements, which suggest that the near-surface region of the air sensitive NaI crystal seriously degrades, even in a moisture-free environment, resulting in a significantly lower value of the refractive index near the surface. First-principles theoretical calculations of the NaI refractive index that agree with the measured values within 0.025-0.045 are also presented and discussed.

Growth, thermal and optical properties of a novel nonlinear optical material K3B6O10Cl

A high quality single crystal of K3B6O10Cl with dimensions up to 25 × 11 × 7 mm3 was successfully grown by the top-seeded solution growth method for the first time. Morphological analysis reveals that the growth of the crystal is anisotropic. By the minimum deviation technique, the refractive indices of the crystal were measured and fitted to the Sellmeier equations. The limit of type-I phase matching second harmonic generation wavelength was calculated to be 255 nm. The transparency spectrum shows that the as-grown crystal is transparent in the wavelength range of 180–3460 nm. The thermal properties and laser damage threshold have been investigated. The two principal coefficients of thermal expansion along a and c axis were measured to be 3.08 × 10−6 and 28.4 × 10−6 K−1.

Crystal growth and optical properties of a noncentrosymmetric haloid borate, K3B6O10Br

A high quality single crystal of K3B6O10Br has been grown with sizes up to 14 × 12 × 7 mm3 by the top-seeded solution growth method. It crystallizes in a noncentrosymetric trigonal system, space groupR3m with cell parameters a = 10.1153(8) A, c = 8.8592(14) A, Z = 3, V = 785.02(15) A3. K3B6O10Br has a three-dimensional network consisting of B6O13 units, which are surrounded by a K–Br framework. A transmission spectrum of the K3B6O10Br crystal was reported. Its refractive indices were measured by a minimum deviation technique and fit to Sellmeier equations. Nonlinear optical measurements demonstrate that the material has second harmonic generation properties, with efficiency approximately three times that of KH2PO4.

Measurement of the refractive index of the LAB-based liquid scintillator and acrylic at RENO

In this paper, we describe the first measurement of the refractive index of the linear alkyl benzene (LAB)-based liquid scintillator and acrylic used at the Reactor Experiment for Neutrino Oscillation (RENO). The refractive index of a material is an important optical property and the prism spectrometer is the most common device for measuring the refractive index. Using the minimum deviation technique, which requires an exact measurement of the apex angle, we determined the refractive indices at six different wavelengths and then fitted them. We also compared the refractive index of the LAB-based liquid scintillator with the refractive indices of other liquid scintillator solvents commonly used in reactor neutrino experiments.

Growth and Properties of Single Crystals of Noncentrosymmetric Na3VO2B6O11

A new nonlinear optical crystal, Na3VO2B6O11, has been grown by the top-seeded solution growth method using a Na2CO3−V2O5 flux. The structure of the compound was determined by single-crystal X-ray diffraction. It crystallizes in the noncentrosymmetric orthorhombic system, space group P212121, with cell parameters a = 7.7359(9) Å, b = 10.1884(12) Å, c = 12.5697(15) Å, V = 990.7(2) Å3, and Z = 4. Na3VO2B6O11 has a three-dimensional structure consisting of hexaborate groups connected by VO4 tetrahedra with the sodium atoms distributed in channels through out the three-dimensional network. The refractive indices have been measured by the minimum deviation technique and fit to the Sellmeier equations. Nonlinear optical measurements on the compound demonstrate that the material has second harmonic generation properties, with an efficiency approximately the same as that of KH2PO4.

Growth, Structure, and Optical Properties of a Congruent Melting Oxyborate, Bi2ZnOB2O6

A single crystal of Bi2ZnOB2O6 has been grown with sizes up to 18 × 13 × 6 mm3 by the top-seeded growth method for the first time with high quality. It crystallizes in the orthorhombic system, space group Pba2 with unit-cell parameters a = 10.8200(7) Å, b = 11.0014(7) Å, c = 4.8896(3) Å, Z = 4, V = 582.03(6) Å3. Bi2ZnOB2O6 has a three-dimensional network consisting of ZnB2O76- layers alternating with six-coordinated Bi3+ cations along the c axis. Transmission spectrum of Bi2ZnOB2O6 crystal was reported. The refractive indices of the crystal were measured by the minimum deviation technique and fitted to the Sellmeier equations. The powder second-harmonic generation (SHG) properties measured by the Kurtz−Perry method indicate that Bi2ZnOB2O6 is phase-matchable.

A New Promising Nonlinear Optical Crystal for Ultraviolet Light Generation: Ca5(BO3)3F

Single crystals of calcium fluoroborate, Ca5(BO3)3F (CBF), have been grown by the flux method with various proportions of LiF. This compound was investigated for nonlinear optical applications and was expected to exhibit an extended transparency window in the ultraviolet. The growth cracking and inclusions in the as-grown crystal boule are discussed. CBF crystallizes in the noncentrosymmetric space group Cm (Z = 2) with a = 8.134(3) A, b = 16.062(5) A, c = 3.5422(9) A and β = 100.88(2)°. The structure is built from [BO3]3− anionic groups and is closely related to the one of calcium oxoborates like YCa4O(BO3)3 (YCOB). The UV absorption edge was measured and compared with the one of YCOB. The refractive indices were measured by the minimum deviation technique and fitted to the Sellmeier equations. The noncritical phase matching (NCPM) wavelengths for harmonic generation are reported.

BaCaBO 3F: A nonlinear optical crystal investigated for UV light generation

A single crystal of BaCaBO 3F (BCBF) has been grown by the Czochralski pulling method in air. This compound was investigated for nonlinear optical applications especially in the ultraviolet. This BCBF material has a hexagonal structure with P6¯2m space group ( Z=3) [D.A. Keszler, A. Akella, K.I. Schaffers, T. Alekel, Mater. Res. Soc. Symp. Proc. 329 (1994) 15]: its cell parameters are a=9.0489(8) Å and c=4.3257(4) Å. Its basic structural unit is [BO 3] 3− [D.A. Keszler, A. Akella, K.I. Schaffers, T. Alekel, Mater. Res. Soc. Symp. Proc. 329 (1994) 15] group. The UV absorption edge was measured at 210 nm. The refractive indices were measured by the minimum deviation technique and fitted to the Sellmeier equations. In this article, second harmonic generation (SHG) and third harmonic generation (THG) phase-matching angle calculations are discussed.

Growth and characterization of a nonlinear borate optical crystal: BaNaB 9O 15

Single crystals of BaNaB 9O 15 (BNBO) have been grown by the Czochralski pulling method in air. This compound was investigated for nonlinear optical applications and was expected to exhibit an extended transparency window in the ultraviolet. The transmission spectrum of the crystal obtained is reported. The refractive indices were measured by the minimum deviation technique and fitted to the Sellmeier equations. The phase matching (PM) angle for type I SHG of 1064 nm Nd:YAG laser was calculated to be θ=58.0°. Because BNBO possesses a very weak effective nonlinear optic coefficient and admits neither third-harmonic generation (THG) nor FHG of 1064 nm laser, it is not interesting as a nonlinear material for UV light generation.

Effects of ion concentration on refractive indices of fluids measured by the minimum deviation technique

AbstractThe prism minimum deviation technique has been used to measure the fluid dependence of refractive indices. Fluids with varying ion concentration (0 to 1.0 M) and varying protein concentration (0.01‐10 mg/ml) have been examined and the measurements show that these parameters influence the refractive index values. Also it is shown by simulations that it is important to take the change of refractive index of the fluid into account when evaluating insitu protein adsorption measurements. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Second-harmonic generations of blue light in nonlinear optical crystals of Gd_1−xLu_xCa_4O(BO_3)_3 and Gd_1−xSc_xCa_4O(BO_3)_3 through noncritical phase matching

Nonlinear optical borate crystals of Gd1−xSCxCa4O(BO3)3 and Gd1−xLuxCa4O(BO3)3 have been grown and characterized. By changing the composition of these crystals, their optical birefringence can be controlled to obtain second-harmonic generations (SHG) in the ranges of 790-824 nm along the Y axis and 920-963 nm along the Z axis through noncritical phase matching (NCPM). The refractive indices of grown crystals were measured with a minimum-deviation technique. The experimental results of NCPM conditions for SHG are in good agreement with the theoretical predictions.