| 摘要 |
1301082 Measuring refractive index photo-electrically; measuring state of charge of a battery RICHMOND ELECTRONICS (MARKYATE) Ltd 13 Feb 1970 [14 Nov 1968] 54169/68 Headings G1A and G1U [Also in Divisions G2 and G4] The refractive index of a fluid is measured, in order to determine the specific gravity thereof, by means of a probe comprising a translucent block 1, means 4 for directing light towards a surface 2 of the block which forms an interface with the fluid, and means for receiving light distributed along a line 6 reached by the light after internal reflection at the interface, the extent of illumination along the line being dependent on the refractive index of the fluid. The probe may monitor flowing fluids or designed for use in testing inaccessible fluids, for example, in a battery, the state of charge of which is to be checked by determination of the specific gravity, Fig. 4. The light source which may be a permanent emitter of the type employing a beta source and which may be monochromatic may be mounted at one corner of block 1, which may be of plastics or glass, a shield member 5 being provided internally of the block, to prevent light passing direct to detection surface 6. One or more photo-cells or photodiodes may be mounted adjacent face 6 to provide an analog or digital measure of the illuminated part y of face 6. Alternatively, Fig. 2 (not shown), light may be conducted to the corner by a fibre optic guide (7) and a row (8) of fibres be mounted at face 6, these being associated with an equal number of photo-cells at a remote location for digital measurement or with a single photo-cell sensing the total intensity issuing from the fibres of Y. A single fibre or cluster of fibres may be used to determine refractive index changes in a very narrow range and may be associated with a further single fibre to sense the direction of change. In an alternative form of block, Fig. 3 (not shown) face 6 is at an obtuse angle to the interface, for greater sensitivity. Circuit Fig. 5 for a multi-cell battery monitor, has probes for each cell of the battery producing refractive index and temperature indications. Various summing circuits and a comparator are used to produce a temperature compensated measure of mean charge which is indicated and/ or used to control charging. |
