3/5$-2 AUTOMATIC POLARIMETER OPERATING INSTRUCTION Please read through these operating instruction before using MRC.VER.01-. CONTENTS I. APPLICATIONS………………………………………………….1 II. PERFORMANCE…………………………………………………1 III. CONSTRUCTION AND PRINCIPLE……………………………2 IV. HOW TO USE…………………………………………………….4 V. MAINTENANCE……………………………………………….....6 VI. COMMON BREAKDOWN AND HANDING…………………...6 I. APPLICATION The polarimeter is a kind of instrument for measuring the optical rotation of a substance. Through measuring the optical rotation, the polarimeter can be used to analyze the concentration, content, and purity of a substance. The 3/5$-2 automatic polarimeter utilizes the photoelectric detection automatic balance principle and the results are displayed by LCD. It not only preserves the advantages of 3/5$—1 polarimeter, but also overcomes the shortcoming of inconvenience in reading. 3/5$-2 automatic polarimeter is characterized by its small size, high sensitivity, human error-free, easy reading, and so on. Furthermore, this instrument is also suitable to the sample of low optical rotation which is difficult to be analyzed by visual polarimeter. Therefore, it can widely be used in various fields of the organic chemical industry. Agriculture: use in contents analyses of agricultural antibiotic, hormone, microbial agro-pharmaceuticals and agricultural products. Medication: use in analyses of antibiotic, vitamin and glucose and in pharmacological research of Chinese medicinal herbs. Food: use in analyses of sugar, monosodium glutamate and soy sauce, in inspection of their final products and determination of sugar content in food. Petroleum: use in analyses of mineral oil and in control of oil ferment process. Essence: use in analyses of essential oil. Health: use in analyses of diabetics’ urine. II. PERFORMANCE Measuring range: ±45° Accuracy: ±0.02° (-15° ≤optical rotation ≤+15°) ±0.05° (optical rotation<-15° or optical rotation>+15°) Minimum sample transmittance: 10% Repeatability: ≤0.01° Minimum indicating value: 0.002° Monochromatic light source: LED (589.44nm) Sample tube: 200mm, 100mm Power supply: 220V±22V, 50Hz±1Hz Outer size: 600mm × 320mm × 220mm Weight (net): 30kg RS232 interface III. CONSTRUCTION AND PRINCIPLE The polarimeter utilizes LED, a small aperture stop and a lens to make up a collimated point light source as shown in figure 1. The parallel light passes through polarizer and becomes a polarized light whose vibration direction is denoted by line OO in figure 2a. When the polarized light is passing through the Faraday modulation coil, its vibration direction will generate a β angle swing (50Hz), as shown in figure 2b. Then the polarized light passes through the analyzer and is projected onto the photomultiplier, an ac signal will be produced. The optical zero point of the polarimeter is obtained when the polarization plane of the polarizer is perpendicular to that of the analyzer (i.e. OO⊥PP), and at the time α = 0 (see figure 3). A photo-signal of 100Hz will be obtained at the optical zero point, due to the β angle swing which is generated by the Faraday coil, as shown in curve C. But in the case where samples α 1 ° and α 2 ° exist, two 50Hz signals with inverse phases are obtained, as shown in curve B’ and D’. Therefore, this will enable the servomotor with an operating frequency of 50Hz to be driven. The polarizer will be turned through α angle ( α = α 1 , or α = α 2 ) by means of a worm-worm wheel. Now, the polarimeter has returned back to the optical zero point. At the frequency of 100Hz the servomotor keeps stationary and the optical rotation of the sample is indicated. 1.LED 2.Condenser 3.Lens 4.Polarizer 5.Modulator 6.Collimator 7.Sample Tube 8.Analyzer 9.Lens 10.Filter 11.Aperture 12.Detector 13. Auto H.V 14.Pre-AMP 15.FREQ-Selection 16.Power-AMP 17.Non-Linear control 18.Speed-Feedback 19.Servo Motor 20.Drive Gear 21.Coder 22.Display Fig.1 Block Diagram A D' B' t t a -90° B a C ββ a 0 a t +90° a a D ββ C' t ββ Curve A: light intensity varied with the magnitude of optical rotation α Curve B,C,D: optical rotation αvaried with time t due to Faraday effect (βswing) Curve B',C',D': photo-current varied with time t—photo-signal Figure 3 IV. HOW TO USE Operation The instrument can be operated under normal illumination, temperature and moisture. Extreme heat, excess moisture and corrosive gases may cause damage to it. The instrument should be placed on a sturdy and roughly level support. Insert the power plug of the instrument into the 220V power source. [It is required to use an AC electronic voltage regulator (1 kVA).] And connect the grounding terminal to the earth reliably. Put the test tube containing distilled water or other blank solvent into the sample chamber, and close the cover. After the indicating value has got stabilized, press the “clear” button. If there are air bubbles in the test tube, the first thing should be done is to make the air bubbles float on the protruded tube-neck. The atomized water-drops on the both ends of the test tube should be wiped dry. The screw-nut of the test tube should not be screwed down too tightly, so as to avoid stress, otherwise, the readings may be affected. When placing the test tube, care should be taken for the marked position and direction. Take out the test tube, then, inject the sample to be measured into the test tube. According to the same position and direction, put the test tube into the sample chamber, then close the cover. Now the instrument will indicate the optical rotation of the sample, “1” will shows on the LCD. Remark: use the sample to wash the tube (inside) three or five times before measurement. Press the “Re-M” (repetition- measurement) button once, “2” will shows on the LCD, the instrument display the result of 2nd measurement, press the “Re-M” button again, “3” will shows on the LCD, display the result of 3rd measurement, press the “1 2 3” button, shift display the values of measurement each time, press the “Average” button, display the value of average, the diode “AV” light. If the polarized angle of the sample exceeds the measuring range, the instrument will be oscillating at ±45°, at this time, the test tube should be taken out, then the instrument will reset to zero automatically. After diluting the sample, measure again. Temperature correction After taking the temperature of the sample, correct the measured result by calculation. V. MAINTENANCE The polarimeter should be placed in a dry place with good ventilation and kept from corrosion. The instrument should be handled with care and vibration is not allowed. The light source can be cleaned or changed if it is dirty or faulty. If the instrument mechanism is operated in great friction, it is advisable to put some oil into the bevel gears, the worm gear as well as the worm through the rear door. If the instrument is damaged or some other parts are in failure, please ask professional to check or contact with our repair department. 1. LED 2.Faraday Coil 3.Digital Display 4.Sample Chamber 5.Worm Gear 6.Correcting Slide 7. Holding Screw 8.Photo-Detector 9.Pre-A.M.P 10.Supply Transformer 11.Power Socket 12.Coder and Motor 13.Digital Board 14.Phase Potentiometer 15.Non-Linear Potentiometer 16.Freq-Selection Board 17.Power AMP. Board 18.Gain Potentiometer 19.Damp Potentiometer 20.H.V. Potentiometer 21.Current adjuster of sodium lamp 22.Light Source & H.V Board 23.Fan 24.Heat Sink 25.Servo motor Fig.4 Inside View The instrument was calibrated before leaving our factory. If test values deviate from the correct ones, the instrument should be regulated with our standard quartz test tube (available to customer’s order) or with the sample whose Optical Rotation is accurately known. Fig4 is the inside view of the instrument after taking off its top cover Undo the holding screw shown in Fig.4, correct the test value by slightly moving the correcting slide until the standard value is obtained. Then tighten the holding screw. If the procedure above doesn’t succeed somehow, send the instrument back to our factory for a thorough inspection. VI. COMMON BREAKDOWN AND HANDING Breakdown Appearance ANALYSES FOR REASON Handling method After turning on the power The LED or the fuse is Change source (AC), the lamp doesn’t break. light up. After turning on the power The LED is break. Change source (DC), the lamp doesn’t The power board is break. Send to our repair light up. department. The instrument can’t balance The light can’t go through Clear sundries. automatically. the sample chamber. The lamp is not lit up Waiting. completely. The high voltage or Send to our repair servosystem has problem. department. No display or display not Display circuit has problem. Send to our repair completely department. The sound is too loud. Mechanical friction Open the rear door, moving parts oiling. Repeatability is bad and value is The lamp is aging. Change deviating. Send to our repair The optical system has dust. department.
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