Refractometer – Rudolph’s Digital J57HA Heavy Use, High Accuracy, QC Instrument for Food Quality Testing.

The J57HA is part of the Rudolph Research Refractometer Product Line The Rudolph J57HA refractometer was designed to meet the unique needs of food quality testing where the automatic refractometer is viewed as a quality control (QC) tool rather than a laboratory instrument. A single flat measurement surface, automatic electronic temperature control, and one button measurement capability make it perfect for heavy use food industry applications, where fast, automatic, and accurate Brix readings are required.

Automatic Measuring System

The Rudolph J57HA features a fully automatic measuring system. The operator simply places the sample on the prism, presses a button and the results are displayed on 7.5cm x 10cm back lit LCD. There are no shadow lines to match and there is no eyepiece requiring operator determination or manual adjustment.

Automatic Refractometer With Electronic Temperature Control

BRIX readings are very sensitive to temperature changes while food industry samples tend to arrive at the refractometer either very hot or very cold. Temperature related variations in BRIX readings can be minimized by using the ICUMSA temperature correction for sucrose, but only minimized, not eliminated. The ICUMSA Temperature Correction Table was developed for a sucrose and water solution and the further from pure sucrose and water the sample is, the more inaccurate Temperature Correction becomes. Temperature Correction also requires that the sample temperature remains stable during the measurement. So a room temperature sugar solution measurement works reasonably well, but if a sauce sample or syrup comes from a kettle or a refrigerator, temperature correction will be almost useless. The solution to measuring hot samples has always been to control the sample temperature with a circulating water bath and then clean and maintain the water bath. This is still not ideal as bringing samples to temperature with a water bath is slow and maintaining a water bath is time consuming. The J57HA’s refractometer addresses this issue with a built in, maintenance free, electronic temperature control which provides the best solution for these real world problems: absolute accuracy regardless of sample type and excellent thermo stability no matter what the sample or environmental temperatures are.

High Accuracy

The J57HA was designed for the food industry with a BRIX range of 0 – 100% and a Refractive Index range of 1.33 – 1.53 RI. The J57HA has a ±0.01 BRIX and ±0.00002 Refractive Index (RI) accuracy, which matches the accuracy of Rudolph’s best refractometers. Combined with absolute temperature control the J57HA delivers high accuracy and consistent readings, perfectly designed for rigorous Food Industry applications.

Easy to Clean Measurement Surface

Regardless of the specified instrument accuracy the real world performance will always depend on how well the instrument is cleaned between samples. The J57HA refractometer addresses this issue by providing a very flat easy to clean measurement surface with no corners or crevices that tend to trap sugars, syrups, and other food industry samples.

High Durability Sapphire Prism

When a traditional automatic refractometer is used in a high throughput application, prism replacement becomes a regular task. This is because traditional Abbe refractometers have glass prisms which are much softer than the sapphire prism of the rugged J Series refractometers and thus more prone to scratching and general wear and tear which can result in inaccurate readings potentially unknown to the operator.

Lower Cost of Use over ABBE Refractometers

Traditional industry has used an ABBE refractometer either with or without a water bath. The cost of replacing the water bath and the Abbe dual glass prism over time makes the cost of owning a Rudolph Research J57HA with its single sapphire prism and electronic temperature control, actually less than the cost of an Abbe over their comparable useful lives. The speed and accuracy of readings also increases productivity and reduces costly mistakes that can be potentially caused by inaccurate readings.


The J57HA Automatic Refractometer offers 1 or 2 point calibration. The instrument stores the date and the time of the last calibration in line with ISO and similar standards. Regardless of how many times the refractometer is calibrated it can always be restored to the default factory calibration.

User Configurable

Versatile laboratory instruments have advantages when applications change however this versatility can also lead to confusion during regular production use with extra buttons and by forcing operators to interpret extra results that have no relevance. The J Series customizable digital 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, making for an even faster user learning curve. The lockout function, calibration and other functions are all password protected.

Touchscreen and Digital LCD

All functions of the J57HA Automatic Refractometer are activated through a large digital, touch screen LCD. The 70mm X 75mm measure button on the J57HA is designed to allow an operator wearing gloves to activate measurement with an elbow or side of a hand. The sealed touchscreen is resistant to fingernails, sharp objects, chemicals and acids.

Password Protection

A combination of password protection and being able to lock out specific “keys” enables control over which users can access certain functions. This means that the J57HA can be set up as a one-button instrument for factory environments.

Printer & Computer Output

In today’s highly regulated environment many users find hard copy or computer record keeping essential. The J57HA comes complete with a standard centronics port for a printer and an RS232 port for direct computer connection to facilitate a permanent information trail.

Return to view the entire Rudolph Research Refractometer Product Line

Refractometer J57HA – Specifications

J57HA Refractometer Specifications
Measurement Scales

Refractive Index (RI)
BRIX (% sucrose)

Measurement Range

1.33 – 1.53 RI,
0 – 100 BRIX


0.00001 RI
0.01 BRIX


±0.00002 RI,
±0.01 BRIX


±0.00002 RI,
±0.01 BRIX

Optical Wavelength



Artificial Sapphire

Light Source

Light Emitting Diode (est. life: > 1,000,000 measurements)

Response Time

Continuous readout or user programmable delay (i.e. a 25°C sample can be cooled to 20°C and measured in 20 seconds)

Communication Interface

Two RS232 ports
One parallel printer port
USB adaptor available

Control Temperature

20°C and 25°C

Temp. Accuracy


Ambient Temp. Limit

10°C – 40°C

Temp. Correction Range

18°C – 95°C (for pure sucrose solutions)

Temp. Measurement & Control

Prism surface


1, 2 or 10 point

Operating Dimensions

L: “16  W: 14″  H: 6″  / 13.6 lbs

L: 40cm  W: 35cm  H:15cm / 7kg

Shipping Dimensions

L: 26″  W: 21″  H: 16″ / 30 lbs.

L: 66cm  W: 54cm  H: 40cm / 14kg

Power Requirements

100-240 volts, 50 Hz – 60 Hz