• Automatic refractometer for full Abbe range.
• High accuracy +/- .00001 ( +/- 0.00002 at high temperature).
• Accessories for flow through operation
• Digital readout of index, temperature, concentration sample ID, time and date
• Only a small amount of sample needed. (0.3 mL)
• Internal menu for customized operations
• User programmable for custom scales.
• Manual or automatic measurement interval.
• Option for up to 30 pre-loaded scales
• Run 2 refractometer heads from one controller
• Membrane keyboard for cleanliness
• RS232 included.
• Data sheet pdf format 

Introduction to high resolution automatic refractometers
The DUR series refractometers from Schmidt and Haensch are sophisticated, microprocessor controlled, critical angle refractometers for measuring the optical density of a wide range of liquid media from low to high viscosity, and independent of opacity and color. The DUR series offers very high accuracy and a wide range of measurable refractive index. There are two different refractometers in the series. The DUR - SW is the very high resolution unit covering the range 1.32000 - 1.53000. The DUR - W2 covers the full Abbe range of refractive index. Both instruments share the same powerful microprocessor based electronics. Each unit can store up to 30 different scales and you can program special scales to suit your own requirements. Optional standard scales include Brix, Ochsle, Zeiss, Beaume, Serum, Protein, alcohols in water and many others. The bright back lit LCD display has 8 lines of 30 characters each. The index, temperature, sample ID, time and date, can be displayed simultaneously. The software also provides for configuration of the printout, formatting of the display and data export.

Refractive Index & Temperature
The refractive index of a substance changes with temperature. Standard references for refractive index are given at a certain temperature - typically 20 degs C. Refractometers are frequently used to measure concentrations or density of solutes by inferring the concentration from the refractive index. Even though the refractive index changes with temperature the concentration of a given solution will remain the same. Temperature compensation scales are used to correct the concentration for the change in refractive index due to temperature.

Concentration & Special Scales
There are many ‘standard’ scales such as the Brix scale where the relationship between refractive index, concentration and temperature are well known for the substances being measured. (Sugars for the Brix scale). For other substances this kind of data may be proprietary or may not exist at all. For some materials such as waxes the refractive index is used as a qualitative standard and temperature corrected index scales are used to standardize the refractive index readings. The DUR refractometer is a microprocessor controlled instrument which can easily be programmed with scales that correct for temperature or concentration or both. The scales are entered via the keyboard and menu structure of the unit. Standard scales such as the Brix, Ochsle, Ethanol or Methanol in water scales are usually pre-loaded into the refractometer, on request, at the factory. But you can program up to 30 standard or proprietary scales using the key-panel to enter the set up menu of the refractometer.

Sophisticated but easy to use
The DUR refractometers are very sophisticated instruments, suitable for advanced research or quality control applications, yet they are very easy to use. A measurement is initiated with a single key stroke. The index data is returned within a couple of seconds. Alternatively the DUR can be set up to automatically take a reading at programmed intervals. The data can be stored, printed or passed to a PC via the RS232 interface.

Engineering Quality
The DURs are manufactured in Berlin by Schmidt and Haensch a company with a long history of innovation and engineering quality in the design and production of polarimeters, refractometers and other optical instruments.