Differential refractometer for liq. chromatography - has interior housing which is temp. controlled to improve accuracy and reduce wt., LED and semiconductor heat source

摘要

The differential refractometer has a light source (12), a lens (13) and a light source slit (14). The optical section (11) has a light path (R) leading from this slit, a collimator lens (18), a measuring cell (19) behind which is a reflecting lens (20) which reflects light onto a light receptor (21). The device is enclosed in a heat conducting casing (22). The novel feature is that the refractometer has a temp. control system (24-28) with a temp. sensor (25), a semiconductor element (28) which acts as a heat source, and a switch (26) which controls the semiconductor element in accordance with the temp. sensed by the sensor. Pref. the light source consists of a light emitting diode, and the housing is covered inside or outside with a thermal insulating foam 1-2mm thick (30) and an Al foil (29). The housing may also consist of an Al block. A slit (16) is located in the light path near the measuring cell, and the housing consists of an Al block. USE/ADVANTAGE - For liq. chromatography. The new device is of light wt., reduced size and higher output. The need to correct the results for variations in internal temp. in the housing is eliminated.