Model J257 has a range between 1.26 to 1.72RI and 0 - 100Brix. The accuracy is +/- 0.0001RI / +/-0.1Brix. The resolution is 0.0001RI and 0.01Brix. The temperature control range is between 15 deg C to 70 deg C. The communication interface is through 2 RS232, one parallel printer port and one auxiliary port.

Upto 100 User Programmable Scales can be built in this machine. The setup can be done in a few minutes by entering 2, 6 or 10 data points of concentration and corresponding RI value. Then we need to press Compute and the instrument creates a new custom scale. The customs scale could also include Butyro which is a calculated value from RI.


Rudolph Research Analytical, working together with refractometer users from the polymer, petroleum, pharmaceutical and essential oil industries, has developed the J257 Wide Range Automatic Refractometer. The J257 Refractometer features include electronic cooling and heating with an extended refractive index range.


The J257 is designed as a multi purpose refractometer for a broad range of refractive index applications. The wide refractive index range of 1.26-1.70 means that this instrument can measure many materials that a refractometer with a food refractive index range of 1.33-1.53 cannot.


Operating the J257 is as simple as placing a sample on the prism, closing the cover and reading the answer — all in just a few seconds. There are no shadow lines to match and there is no eyepiece requiring any kind of operator determination or manual adjustment. When the "measure when stable" mode is selected, the J257 automatically waits until the sample has been heated or cooled to a predefined temperature before initiating a measurement.


A large 7.5cm x 10cm cold cathode fluroescent back lit graphics LCD allows the scale, sample temperature, set temperature, air temperature, time, date, and temperature correction status to be easily viewed. All functions are activated through a touchscreen panel that will not wear out or get misplaced like traditional or detachable keyboards. The touchscreen is resistant to fingernails, sharp objects, chemicals, and acids.

Dual Temperature Control System

Unlike other temperature controlled refractometers, the J257 has temperature control from both above and below the sample. The sample cover is controlled to the same temperature as the prism and, when lowered, is designed to provide a temperature controlled micro environment that provides unrivaled temperature stability, fast measurement time and minimal evaporation. Depending on options, the sample cover can also be used to initiate measurement. This means that the operator doesn't even need to touch the refractometer screen on a day to day basis, simple lower the cover and measurement starts automatically.


Optional Sample Presser

The J257 is available with an optional Temperature Controlled Sample Presser that touches the sample. Compared with the standard temperature controlled Cover, the optional Presser reduces the empty volume of the measurement area thereby decreasing evaporation and at the same time helping to evenly spread semi solid materials over the measurement prism. These features offer improved performance on many samples.



The J257 Refractometer offers 1 pt, 2 pt, or a full multi-point calibration. Calibration can be done at 20°C, 25°C or any user selectable temperature within the available range. Regardless of how many times the refractometer has been calibrated, it can always be restored to the initial factory calibration if required.

User Configurable

alt Versatile instruments have the advantage of being able to display a lot of information, however this versatility can also lead to confusion, with extra buttons and by forcing the operator to interpret extra information that may have no relevance to their application. The J Series customizable display allows the instrument to be configured to exactly what is required for each application. The customizable keypad can be "locked out" or just a few keys can be operable, i.e. the measure key, print key, zero key, customer specified sample keys or any combination thereof. The lockout function, calibration and other functions are all password protected.


The J Series refractometer offers a sapphire prism for high mechanical and chemical durability. The sample well is made of acid resistant 316 stainless steel with a techtron sealing ring. There is no lamp to change, the LED light source is guaranteed for 1,000,000 measurements.

Options and Accessories

  • NIST traceable calibration liquids
  • IQ/OQ/PQ package
  • Acid resistant sample well and plate
  • Printer
  • Pre-programmed custom scale
  • Data capture software
  • Small volume sample well
  • Different measurement wavelengths
  • Barcode reader


J257 Refractometer Specifications

Measurement Scales Refractive Index (RI)
BRIX (% sucrose)
Temperature Corrected BRIX
Temperature Corrected RI
100 User Programmable Scales
Measurement Range 1.26 - 1.70 RI,
0 - 95 BRIX
Resolution 0.0001 RI
0.01 BRIX
Reproducibility ±0.0001 RI,
±0.1 BRIX
Accuracy ±0.0001 RI,
±0.1 BRIX
Optical Wavelength 589.3nm (other wavelengths available)
Prism Artificial Sapphire
Light Source Light Emitting Diode (est. life: >100,000 hrs.)
Response Time Continuous readout or user programmable delay (i.e. a 25ºC sample can be cooled to 20ºC and measured in 20 seconds)
Communication Interface Two RS232 ports
One parallel printer port
One auxiliary port
Analog Control 0-10 volts, 4-20 mA
Temp. Control Range 15ºC - 70ºC
Temp. Sensor Accuracy ±0.05ºC
Ambient Temp. Limit 10ºC - 40ºC
Temp. Correction Range 18ºC - 95ºC (for pure sucrose solutions)
Temp. Measurement & Control Prism surface and presser
Calibration 1, 2 or full multi-point calibration
Operating Dimensions L: 15.25" W: 10"  H: 4.5"  / 23 lbs.
Shipping Dimensions L: 26" W: 21"  H: 16" / 30 lbs.
Power Requirements 100-240 volts, 50 Hz - 60 Hz
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