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.
