Brix is used in the food industry for measuring the amount of sugars in fruits, vegetables, juices, wine, soft drinks and in the starch and sugar manufacturing industry. For fruit juices, 1.0 degree Brix is denoted as 1.0% sugar by mass. This usually correlates well with perceived sweetness. Modern optical Brix meters measure critical angle and caculate Brix. The critical angle (the angle beyond which light is totally reflected back into the sample) is a function of the refractive index and the sensor detects this critical angle by noting where a dark-bright boundary falls on a CCD camera. The critical angle value then will be calibrated in Brix or refractive index. Our digital refractometer finds the critical angle, but the light path is entirely internal to the prism so that the critical light beam never penetrates the sample. This makes it easier to read turbid samples. The light/dark boundary, whose position is proportional to the critical angle, is sensed by a CCD array. The prism mount contains a thermometer which is used to correct the Brix to 20°C.