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Digital Refractometer – J157 High Accuracy for Food, Beverage, Water Based Chemicals, & Sugar Industries.

Rudolph Research Analytical, working together with refractometer (Refraktometer) users from various countries and disciplines, has developed the J157 Automatic Digital Refractometer. The Rudolph J157 benchtop combines features and accuracy that meet the most demanding applications both in and out of the laboratory and shares many features with the Rudolph Research line of Laboratory Refractometers.

Application – Food and Chemical Labs

The J157 is designed as a high accuracy automatic refractometer for food and water based chemical applications. The instrument can read to ±0.00002 RI / ±0.01 BRIX making it more accurate and reproducible than 4 decimal place wide range chemical refractometers.

Refractometer Operation

Operating the J157 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 type of operator determination or manual adjustment as necessary with ABBE type refractometers. When the “measure when stable mode” is selected, the J157 automatically waits until the sample has been electronically heated or cooled to a predefined temperature before initiating a measurement.

Dual Electronic Temperature Control System

Unlike other temperature controlled refractometers, the J157 has electronic 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 an automatic measurement.

Optional Sample Presser

The J157 digital refractometer 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 greatly reducing evaporation and at the same time helping to evenly spread many types of materials including semi solids, and pastes over the measurement prism. This feature offers improved measurement performance on many samples.

Auto Measure Option

The Rudolph Auto Measure Option allows the closing and opening of the presser to start and end a measurement. The operator just closes the cover to start measuring and lifts the cover to stop measuring. The closing and lifting of the lid functions as the start/stop in the measurement process without ever touching the measure button.

Easy to Clean Refractometer Sample Well

No matter how great the refractometer is, accurate results will only be obtained if the prism is clean. All Rudolph J Seriesrefractometers offer a flat, easy to clean prism that makes the cleaning process between measurements simple, even with sticky samples.

User Defined Scales

The J157 can be supplied with a large range of standard and customized scales. Scales can be customized in a few minutes. Simply enter 2, 6 or 10 points of concentration vs. corresponding RI data, and the instrument calculates the custom scale automatically.


The J157 offers 1 point, 2 point 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

Versatile laboratory instruments have the advantage of being able to display significant amounts of information, however this versatility can also lead to confusion, with extra buttons and by forcing operators to interpret extra results that have no relevance to their application. The Rudolph J Series customizable display allows the refractometer to be configured to exactly what is required for each application. The customizable digital 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.

High Durability Sapphire Prism

The J series refractometers offer 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.

Digital LCD Touchscreen

Refractometer Screen

The J157 Refractometer’s large 7.5cm x 10cm cold cathode fluorescent back lit digital LCD screen allows the scale, sample temperature, set temperature, air temperature, time, date and temperature correction status to be easily viewed. All functions are activated through the digital, touchscreen panel which will not wear out or be misplaced like traditional or detachable keypads. The rugged touchscreen is impervious to sharp fingernails, sharp objects, chemicals, and acids.

Simple Yet Flexible

Operating the J157 can be as simple as placing a sample on the prism, closing the presser and reading the answer – all in just a few seconds. The entire 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, like calibration and other functions are all password protected.

Refractometer Sample Presser


J157 Refractometer Specifications
Measurement Scales Refractive Index (RI)
BRIX (% sucrose)
Temperature Corrected BRIX
Temperature Corrected RI
Urine SG
30 User Programmable Scales
Measurement Range 1.33 – 1.53 RI,
0 – 100 BRIX
1.0000 – 1.0400 Urine SG
Resolution 0.00001 RI
0.01 BRIX
0.0001 Urine SG
Reproducibility ±0.00002 RI,
±0.01 BRIX
Accuracy ±0.00002 RI,
±0.01 BRIX
Optical Wavelength 589.3nm
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 – 50ºC
Temp. Sensor Accuracy ±0.05ºC
Ambient Temp. Limit 10ºC – 40ºC
Temp. Correction Range 18ºC – 95ºC (for pure sucrose solutions)
Temp. Control Prism surface and in the cover
Calibration Using water or NIST traceable standards
Operating Dimensions L: 15.5″  W: 10″  H: 5″  / 23 lbs.

L: 39.5cm  W: 25.5cm  H: 13cm / 10.4kg

Shipping Dimensions L: 26″  W: 21″  H: 16″ / 30 lbs.

L: 66cm  W: 53.5cm  H: 41cm / 14kg

Power Requirements 100-240 volts, 50 Hz – 60 Hz



Calibration liquids from 1.33 – 1.70 (available with 4 decimal & 5 decimal accuracy).
Continuous Flow and Pour-ln Style Pressers allow samples to be continuously monitored or poured directly from a beaker. The J157 standard presser is easily removable with a captured hinge pin and replaced with a Pour-In presser as shown at right or a Continuous Flow presser with an inlet and outlet port. In all cases, volume required for measurement is less than 5ml. Please contact the factory or use our Information Request Form for more details.

Refractometer Sample Delivery Options

Scientific Solutions

Scientific Solutions have been providing carefully selected laboratory and analytical equipment to Australian Industries such as Environmental, Pharmaceutical, Food and Beverage and Research markets of the Science Industry for over a decade.

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