High Resolution 
Automatic Lab Refractometers

Features of ATR-SW Automatic Refractometers

• Quick readout - one key press for instant high resolution reading
• Fully Automatic - simply load a small sample and press one button.
• Digital readout of refractive index, Brix and sample temperature.
• Temperature compensated Brix readings for samples from 15 to 40 Degs C.
• Only a small volume (0.3ml) sample needed
• Many optional configurations for temperature control and automatic sample handling with funnels, peristaltic pumps, vertical door etc...
• RS232 data port.
• Built in diagnostics

Introduction to Automatic Digital Refractometers

Refractometers are widely used to measure the amount of dissolved substances in solutions containing mainly sucrose. The relationship between refractive index and the amount of dry substance content is well known for sucrose and is the basis of the Brix scale which is measure of the number of grams of sucrose present per 100 grams of aqueous sugar solution. (50 Brix means 50 grams of solid per 100 gms of solution) This relationship holds for a large number of similar substances and so the Brix scale is widely used in the food industry. The refractive index of a sugar solution changes with temperature while its solid content remains the same. ( The same refractive index at different temperatures correspond to different Brix values.) Manual "Abbe" refractometers do not compensate for this temperature effect and manual correction tables are used to adjust the readings to a standard temperature.

The Schmidt and Haensch range of automatic Refractometers supplied by Topac measure both the refractive index and the temperature of the sample in order to evaluate the Brix value. They read out both the actual refractive index and the actual sample temperature, but they automatically correct the Brix value to what it would be at 20 degs C. regardless of the actual sample temperature. ( In the range 15 - 40 C)

The ATR SW is a high accuracy  refractometer having a resolution of 0.00002 refractive index and 0.02 Brix. The refractometer prism and sample holder are external to the electronic unit and can be used in either the horizontal position or in a vertical position with a flow through cell and funnel. The sample holder is fitted with re-circulating temperature control circuit for stabilizing the sample temperature with re-circulating fluid from a temperature controlled bath. The sample door used in the vertical flow through version may also be hooked into the temperature control circuit providing a highly stable thermal mass all around the sample. The vertical mode of operation is very useful for monitoring a continuous flow of sample liquid. In this case the electronics can be set up to make measurements at predetermined intervals from 1 to 99 seconds. The vertical orientation is also useful for samples where solid particles may settle during measurement - in the vertical mode such particles do not settle on the measuring prism.
The ATR S is a continuous flow through version of the above, for use as a cane sugar purity analyzer in combination with the SACCHAROMAT polarimeter. This unit includes a stainless steel flow through cell, vertical prism orientation and RS232 interface.