SU603261A1 - Device for verification of differential refractometers - Google Patents

Description

The device contains a glass wedge 1, a frame 2, a housing 3, a regulating device 4. Structurally, each wedge 1 from a set is mounted into a frame 2, which, in a failure condition, is inserted into the housing 3, corresponding in shape and size to a measuring cell of a rotatable dispersive a refractometer and having a regulating device 4 for orienting the refracting edge of the Kliya and fixing it to the B frame of the selected floor: epia. In the general case, a wedge consisting of two glasses of different grades with different refractive indices and a perpendy; by a 1k entrance of the wedge, the incidence of the light beam of rays (Fig. 1) is calculated using the system of equations WIG sin 5: - П-2С sin ( b - mustache); / i2csin (p - 7-) sin (p - KC); /ii.FSin 9: / g2 / - sin (6 - 7 /) "2 / - sin (p -: - (p - IFJ, (1) where riic, Pzs, n, i- are the refractive indices of the first and the second part of the wedge, respectively, for the wavelengths Ac and kp; 9 is the refractive angle of the first part of the wedge; p is the angle between the last face of the second part of the wedge and the plane perpendicular to the optical axis; Tc, F are the angles between the refracted the boundary of the two parts of the wedge by the beam and the optical axis, respectively, for wavelengths and L. For a single rectangular wedge, Pu (air) and p is absent, therefore the system of equations (1) takes the form II; - COS 7 .; calculating vie d tg6 -. (3) Ls - cos as llF - COS a /. where "from l" are the angles of deflection of the light rays by the wedge, respectively, for the lengths of the will AC and / .. For the wedge, which consists of two parts, whose input and output edges parallel to meleda by themselves and perpendicular to the optical axis (), expression (1) takes the form CL-rx-sin-a /. - Pg, and warrant for calculating V P - 2C -. - P {C ii--, F - siii-a /. On the basis of the indicated dependencies, the angles are calculated and the glasses are selected for the set of wedges required for the calibration of a refractometer that simultaneously measures the differences of the refractive indices A from the front Spurs D (). Both single and double dial wedges allow the calibration of the differential refractometer with a positive and negative deviation of the monitored parameter by turning them 180 degrees around the optical axis. The wedges' requirements for the lmatad are no higher than the second category in DLS and D (n / - - Ps), and the accuracy of making a refractive angle is no higher than –3 arc minutes. Such wedges have stable parameters, a small error from the change in ambient air temperature (1 X of the refractive index unit by 1 ° C) and are convenient in abrasion. This allows them to be used as a calibration tool for differential refractometers having a measurement error (Al s) to 1 U units. and A (l / --- Yas) up to 2 10-5 units. The wedges are certified using a goniometer for the deviation angles for the selected wavelengths i) g. The angles are engraved on the body of the wedge, and the adjustment device is sealed. The certified set of wedges becomes the main calibration tool for the serial production of devices and is stored at the manufacturing plant. To test refractometers working with liquids, a set of wedges is certified by B using the values of the difference between the refractive index Alc and the mean dispersion A () according to a dispersion refractometer, previously calibrated with the help of liquids. Thus, each wedge is certified in the angles of deviation of ac and in the values of the differences of the refractive index and the average dispersion, taking into account the quality of manufacturing the differential juvet and the parameters of the refractometer. An example of the calculation and application of the proposed device. The initial data for the calculation are: the measurement range Alc and A (); angles of deflection of the cuvette used in the differential dispersion refractive meter, corresponding to the measuring ranges. For a differential cuvette of the triple hollow prism type with a measuring part angle of 90 ° | without autocollimation, the range of measuring the difference of the refractive indices DLs 0–200 units corresponds to the angle of deflection of the rays of the cu AC 0 -2 ° 16, the range of measuring the difference of the mean dispersions A (np - Lc) - 0-200 units: q corresponds to the angle D (a / -ac) 0-1336.

To test a differential non-perverse refractometer, a set of nine wedges is needed, selected by refractive indices, dispersions and deflection angles so that the angular deflection of the rays with a wedge ensures simultaneous calibration of the average dispersion for each refractive index point at the beginning, middle and end scales. The initial values of the beam deflection angles for calculating the set of wedges should correspond to the data in Table. one.

Table 1

The refraction of the wedges, the angles of the wedges, the glass marks from which the wedges are made, the angles of deflection of the rays and Лс, the turning points of the refractive index scales and the type of each wedge are presented in Table. 2. Table 2

The wedges 1, 4, 7 are calculated according to the formulas (2) and (3), 5, 8, 9 - according to the formulas (4) and (5), 2, 3, 6 - according to the control system (1).

The verification of the dispersion refractometer is performed as follows.

Using a regulating device, zero values of ps and (nf-Ps) are set on the scale of the recording instrument. Instead of a measuring cuvette, a wedge is inserted into the device, corresponding to the certification of the end of the scales of differences of the refractive indices and average dispersions. Perform setting of the "scale range according to the readings of the recording instrument.

Alternately, certified wedges are installed, corresponding to the combination of differences in the refractive index and average dispersion according to Table. 2, and compare the readings of the recording device with the wedge rating data. According to the test results, the metrological certification of the differential refractometer according to the accuracy class is performed.

A device for testing differential dispersive refractometers that simultaneously measure the refractive index and average dispersion makes it possible to quickly detect possible systematic errors of the device and either eliminate them or introduce appropriate corrections to the measurement results, provides a comprehensive calibration of the device simultaneously on two scales, which important when using a dispersion refractometer to analyze the composition of light petroleum products. In this case, ensuring the specified accuracy class of the dispersion refractometer in the entire measurement range of the average dispersion and refractive index is the basis for accurately determining the group composition of light oil products, which is important for catalytic reforming processes in oil refining.

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Claims (2)

1. Pogarev GV. Adjustment of optical devices. M., 1968, p. 115-127. 2. Instructions 279-66, developed by the Committee of Standards, Measures and Measuring Tools at the Council of Ministers. USSR, 1966. ////////////// Л (/// 7/7 ///// Fig. 2