The LSC Model 725 Process Control Refractometer is a two piece optical/electronic measurement instrument. An in-line sensing head is employed, whereby a sensing window (commonly known as a prism) is wetted by the product to be measured. The electronics and read-out are housed in a separate enclosure located at some nominal distance from the sensing head and coupled to the sensing head by an interconnecting cable.
A unique digital microprocessor is employed which provides a truly linear digital display output regardless of the customer-product non-linearity between refractive index and the read-out terms. Virtually any non-linear refractive index curve can be corrected for, or any shape can be simply produced. For example, the micro-processor can be programmed so that the output terms are the reverse of refractive index. The output units, calibration, and correction curves can all be selected and changed easily by the customer, at will, if desired. The 4-20 mAdc output is affected in a fashion identical to the digital display.
Eliminating downtime and maintenance was the major objective of the Model 725, offering the highest level of reliability. As a result, a sapphire hemisphere is utilized for the "prism," an infrared diode is used for the light source, a dual silicon
detector performs the actual measurement, and a silicon diode is used for temperature sensing. The dual silicon detector, as utilized in the Model 725, offers a fine continuous and stable reading ...eliminating the inherent problems evident with an "incremental step" detection system.