April 20, 2018 | News & Notices High-Accuracy Multi-Wavelength Digital Refractometer with the V-Block Method, Optimal for Measurements of Optical Materials Release of the KPR-300 Kalnew Precision Refractometer


Shimadzu Corporation has released the KPR-300 Kalnew precision refractometer in North America. This instrument can measure the refractive indices of transparent samples for optical applications, including lenses and prisms, to an accuracy of ±4 x 10-5.

The V-block method (also called the Hilger-Chance or Vee-Block method) has been adopted in this product as the measurement method, which enables measurements of refractive indices with excellent accuracy and repeatability. This instrument was developed for use in quality control applications during mass production of glass and lenses, especially molded lenses, by customers who to date have not used Shimadzu precision refractometers.

Shimadzu will gradually expand sales regions of this product.


Background to the Development

In recent years, increasingly higher functionality and performance have been pursued with respect to lenses, prisms, and other optical elements, which are made of glass and plastic materials. In addition, demand has been increasing in applications such as personal cameras, smartphones, in-vehicle cameras, and head-up displays. In such applications, variance in the refractive index of lenses and prisms in the manufacturing process will have an impact on performance. Accordingly, the necessity of measuring refractive indices has become critical not only during research and development, but also during mass production.

The KPR-300 Kalnew precision refractometer uses the V-block method, which provides excellent accuracy and repeatability, with a measurement accuracy of ±4 x 10-5, and repeatability of ±1 x 10-5. The instrument is equipped with spectral lamps, and can perform automatic refractive index measurements and automatic calculations of Abbe numbers at three wavelengths, the d-line (587.6 nm), C-line (656.3 nm), and F-line (486.1 nm), making this instrument a highly practical refractometer. A wide range of refractive index measurements can be accommodated by replacing the sample holder V-block prism, enabling materials even with a high refractive index of 2.0 to be measured.

This product was developed to expand sales for applications such as research and development and quality control with respect to glass molded lenses (which vary in refractive index and dispersion depending on the molding conditions), functional glasses (such as small lenses with a diameter on the order of 3 mm and a thickness of 1 mm, which are used in smartphone and in-vehicle equipment), and functional resins.


1. Adopting the V-Block Method Enables Simple, High-Accuracy Measurements

With the V-block method, samples finished to a 90 degree angle are measured. The finished surface of the sample does not require the finished accuracy of general spectrometer prisms, and a grinding finish is enough instead of polishing, so sample preparation is not time consuming. The instrument is capable of high-accuracy measurements, with a measurement accuracy of ±4 x 10-5, and a display resolution of 0.1 x 10-5. The instrument can also measure resin lenses and glass several millimeters in diameter, which are typically used in smartphones and in-vehicle cameras.

2. Capable of Three-Wavelength d-, C-, and F-Line Automatic Multi-Wavelength Measurements, and Measurements of Samples even with a Refractive Index of 1.8 or Higher

The instrument is equipped with two spectral lamps, and is capable of measuring refractive indices at the three wavelengths required for optical design, and performing calculations of scatter (Abbe number (nd)). In addition, a wide range of refractive indices from 1.20 to 2.05 can be measured by replacing the sample holder V-block prism.

3. Special Software Enables Automatic Measurements

With a single click, the user can switch the lamp lit and measurement wavelength, calculate the refractive index, and calculate the Abbe number. The refractive index for the D-line (589.3 nm), often used for resin materials, is calculated from the results measured at the three wavelengths of the d-line (587.6 nm), C-line (656.3 nm), and F-line (486.1 nm).

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