refractoRudolph's J series Digital Refractometers are automatic, digital systems with an LCD screen. Refractive Index being highly temperature-sensitive the sample's temperature from models J57 and above is controlled by the electronic heating and cooling Peltier technology. Through the keypad the temperature of the sample can be set thus avoiding the use of water-baths which are clumsly, cumbersome and costly.


  • RI Range: 1.26000 to 1.72000
  • Accuracy: up to 4th decimal & 5th decimal depending on application
  • Temp Control: by Peltier electronic heating & cooling, without the need of water bath (from J-57 model)
  • Wide Temp control Range: 10 to 120 deg C
  • Top cover for avoiding sample evaporation
  • Heating & cooling from top & beneath to ensure quick & accurate analysis
  • Inbuilt embedded Windows 7 OS & inbuilt data storage upto 8GB
  • 21 CFR Part 11 inbuilt
  • Smart Measure facility, in case there is previous traces of samples remaining the machine will not allow to load the next sample, so avoidance of cross contamination.
  • The Prism is ultra-flat , so there is no temp gradient & cleaning is very easy. Prisms can be cleaned with paper towels.

J-47: This is the simplest of the models. The HA variant would have a range of 1.32-1.53RI and the WR between 1.29-1.66. Both models would have a Brix range between 0 – 100 Brix and thus is the most suitable one for Food companies which predominantly want to check sugar in their process. The accuracy of J-47HA would be +/- 0.00003RI and that of WR +/- 0.0001RI.

Both the variants would be equipped with a built-in Temperature Correction for Sucrose between 4 to 95 Deg C.

J-57: This model also has the HA and the WR variants. The WR variant has an RI range of 1.30 to 1.7 and the WR-VT variant comes with a temperature control range of 10 to 65 Deg C. The top-cover would be an EP which protects the sample from the environment.

J-157: This model has four variants – HA, HA PLUS, WR & WR PLUS. The HA models would have a range of 1.32 to 1.53RI and the WR 1.29 to 1.66RI. The HA would have an accuracy of +/- 0.00002 RI and the WR models +/- 0.0001 RI. There would be a difference between the model with Plus and without. The Plus variant would have a temperature control range between 10 to 80 Deg C.

J-257: The J-257 has an RI range of 1.26 to 1.72 with an accuracy of +/- 0.0001 RI. The temperature control range would be 10 to 90 Deg C. J-257 comes with the Smart measure feature and Trend Analysis. The Trend Analysis feature is a very important tool in a modern factory that the users want to be aware of fact the moment the results go out of their set limits.

J-357: This machine which is very similar to features to that of J-257 and the difference is in the accuracy levels. The 357 has a accuracy of +/- 0.00002 RI and +/- 0.015% Brix.

J-457: This is the top-of-the line of Rudolph J series Refractometers. The system is packed with many advance intelligent features like SmartMeasure – it finds out if there are any sample residues left on prism surface, if insufficient amount of sample is covering the prism, if there are any sample contamination or improper calibration, if there are any air bubbles in the sample etc.

The RI range is 1.26 to 1.72 and the accuracy is +/- 0.00002RI and +/-0.015% Brix.

The Temperature control range of the samples is 10 to 110 Deg C (120 Deg C with Temp Boost option) and the temperature would be controlled from the Prism and also the cover. The temperature range is very important for a few samples like Petroleum or Petrochemicals where the samples need to be analysed in 100 or higher Deg C.

This model can also have an option of Hastelloy measurement surface if the samples are going to be very acidic.

The models 257 / 357 / 457 can also have an option of RI measurement kit for Solids, Semi-Solids and Films. The kit consists of a punching device and a holder for solids. This punching device is used to punch a sample out of films. This is useful for testing plastic packaging films directly.

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