In this work, we use an Abbe refractometer, the operation of which is based on measuring the limiting refraction angle. The optical diagram of the refractometer is shown in Fig. 4. The test solution is placed between the planes of two prisms - the lighting 3 and measuring 4 , made of glass with a high refractive index ( n = 1.9 ). The large refractive index of the measuring prism allows maintaining the condition n p < n st for a wide range of densities of measured liquids. The instrument scale is calibrated to the value n p =1.7 .From the source 1 a beam of light is directed by a condenser 2 to the entrance face of the lighting prism. Passing the lighting prism 3, light falls on the matte hypotenuse face AB of this prism , bordering a thin layer of the test liquid. The matte surface has irregularities, the dimensions of which are several wavelengths. Light is scattered by these irregularities over the entire surface and, having passed through a thin layer of solution, falls on the “solution-glass” interface at all possible angles of incidence, i.e. the angle of incidence varies from 0 0 before 90 0 .
On the mirror hypotenuse face CD measuring prism 4 light is refracted (the size of the irregularities on this face is less than the wavelength). Due to the fact that n p < n st , the angle of refraction varies from zero to γ etc . At angles γ > γ etc no radiation is observed. Thus, at a refraction angle equal to γ etc , a light-shadow boundary appears. Magnitude n p is determined from the relation sinγ etc = n p / n st , where is the value n st known.
The path of light rays as they exit the measuring prism is easily taken into account when calibrating the device, since light refraction occurs at the glass-air boundary. , Moreover, the refractive indices of both media are known. The angle of light refraction at this boundary does not affect the measurement accuracy n p .
Due to the illumination of the entire layer of solution, the boundary between light and shadow is observed quite sharply. Therefore, when setting up the device for operation, the light from the illuminator must be directed onto the prism so that it evenly illuminates the entire surface of the face. AB diverging prism. To determine the angle at which the rays emerge from the measuring prism, a telescope formed by the lens is used 6 and eyepiece 9, light enters through a system of direct vision prisms 5 . In this case, the property of the telescope is used that the rays coming to it parallel to its axis are collected at the rear focus, where a transparent plate is placed 7 with a grid cross mark on it. The crosshair is exactly in focus.
Rice. 4. The path of rays in a refractometer when measuring the refractive index using the grazing beam method.
Optical design of the device: 1-light source, 2-condenser, 3-illuminating prism, 4-measurement prism, 5-direct vision prism, 6-spotting scope lens, 7-reticle with crosshair, 8-scale, 9-spotting scope eyepiece , 10-field of view of the eyepiece.
Direct vision prisms and the telescope are rigidly connected to each other and can be rotated relative to the measuring prism. The rotation angle is measured using a fixed scale 8, located in the common focal plane of the lens and eyepiece. The scale is graduated in the values of the refractive index of the solution under study based on formula (6). By rotating the telescope, you can set its axis parallel to the rays refracted at the edge CD at extreme angle γ etc. In this case, light and dark areas will be observed in the field of view of the eyepiece, the boundary between which will coincide with the crosshair. The light area is formed by rays refracted at the edge CD at angles less than the limit, and the dark area arises due to the absence of rays traveling at angles greater than the limit. The position of the boundary of light and shadow formed by rays refracted at the maximum angle will indicate on the scale 8 the desired value of the refractive index of the solution.
Light source 1 is not monochromatic. Therefore, due to the dispersion of both the substance under study and the material of the measuring prism (the dependence of their refractive indices on the wavelength of light), the boundary of light and shadow observed through the telescope turns out to be blurred and colored. To eliminate this effect, direct vision prisms are used 5 , forming dispersion compensator. The prisms are designed so that rays with a wavelength λ D= 589.3 nm (average sodium wavelength) did not deviate when passing through them. When one prism is rotated relative to another, their total dispersion changes, which makes it possible to compensate for the difference in the exit angles of rays with different wavelengths from the measuring prism and direct them into the telescope parallel to rays with wavelengths λ D. The boundary between light and shadow is sharp, uncolored and gives the value of the refractive index of the solution under study n D at wavelength λ D .
So, what kind of beast is this refractometer? And what do you eat it with?
The review is a logical continuation of the topic about and belongs to the category “but men don’t know!” :)))
Well, let's get started:
First, a lyrical digression. As you already know, my friends, I am the proud owner of a Chinese moonshine still. It came with a set of three alcohol meters along with a thermometer. And everything would be fine, and everything would be wonderful, if not for one BUT. To measure the percentage of alcohol in a liquid, a decent amount of this very liquid is needed. According to the instructions, it comes out to 300 grams! This is the most important inconvenience. You can no longer measure the degree in a glass.
“Is there such a device,” I asked myself, “that can show the percentage of alcohol using a minimum amount of liquid?” He asked and began to search. It turned out that there is such a device! Almost immediately I came across a device with such a mysterious name - “refractometer”. And my eyes were opened, and I saw that this was good :)
With this miracle device you can measure the percentage of alcohol in a liquid using just two or three drops of it! Refractometers, as it turned out, are a great many. Refractometers for beer, wine, honey, milk, antifreeze, electrolyte, aquarium, etc. But, nevertheless, the principle of operation is the same for everyone. They differ only in their scale and the ability to automatically correct the result depending on the temperature. From 0 to 30 degrees. This is just such a function. There is an ATC sticker and it costs more than a device without temperature correction. It also has a calibration screw, closed with a rubber plug and a screwdriver included.
Now let's turn to Wiki:
“A refractometer is a device that measures the refractive index of light in a medium.
Refractometry is a method for studying substances based on determining the index (coefficient) of refraction (refraction) and some of its functions. Refractometry ( refractometric method) is used to identify chemical compounds, quantitative and structural analysis, determination of physical and chemical parameters of substances. The refractive index n is the ratio of the speed of light in the adjacent media."
Oh how! Neither more nor less, but we are pulling the speed of light itself by the tail! Cool :)))
Once again I am convinced that after drinking moonshine, you can’t pull anyone’s tail! ha ha ha!!!
So how does it work. We take a refractometer. We look through the hole into the light. We focus on the scale. Open the top glass. We put moonshine (vodka, tequila, etc.) into a pipette, drop two or three drops onto the bottom glass and close the whole thing with a clamp with the top glass. Again we look through the hole into the light. Let's smile :)
The scale with uneven graduations looks exactly the same as on the seller’s website. That is, like this. 
The only caveat. The scale in the picture says ALCOHOL. Mine says ALCOHOLIC. A subtle hint though...
Here's what the complete set looks like. 
Refractometer
Pipette
Screwdriver
Napkin
Instructions
Case
Other photos
Neat box-case 
Everything is packed compactly 
Calibration screw 
Open glass 
Eyepiece 
In hand 
I'm planning to buy +54 Add to favorites I liked the review +59 +121
Having chosen beekeeping as a hobby or as the main activity, you need to understand all the instruments and technical devices that help you obtain high-quality, tasty honey. You definitely need to know about a honey refractometer: what is it and how to use it?
At least the requirements modern market the quality of products is not high, many beekeepers still rely on the proven GOST. According to it, the mass fraction of moisture content in honey should not exceed 19-21%.
To obtain such results, it is believed that it is advisable to pump out honey only from those combs that have been covered with wax to three-quarters of the total height. But when pumping out honey, this requirement is not always met, as a result of which the water content in the collected product significantly exceeds the norm.
Honey high humidity is a favorable environment for fermentation processes, which quickly make it unfit for consumption. To avoid such situations, during the collection process you need to strictly control the water content; for this you will need a honey refractometer. It accurately measures the mass fraction of water in the total mass of the product. This device has long been used not only by beekeepers, but also by wholesale honey buyers.
In general, refractometers are designed to test sugar-containing liquids such as fruit juices and drinks, wines and honey. When choosing a device specifically for honey, you need to pay attention to some parameters:
Portable devices are very compact and do not require connection to a power supply. More technologically advanced models are equipped with a built-in temperature corrector, which is a bimetallic plate connected to the optics system of the refractometer itself.
Under the influence of temperature fluctuations, this plate is compressed or, conversely, stretched, thereby smoothly adjusting the operation of the entire measuring system in accordance with temperature conditions. Thanks to automatic calculations of these shifts, maximum accuracy is achieved when measuring humidity in the range from 12% to 27%.
Before purchasing the device, you should carefully read the instructions. Before the first use, it is necessary to calibrate the refractometer. It must be carried out according to the readings of a reference device, using identical honey samples. To make adjustments, you need to clean the calibration screw with a screwdriver and enter the border, which is most often painted blue and white, to read the same as the standard.
Video: refractometer for honey.
Having understood what a refractometer is and how it works, it becomes clear that for maximum accuracy measurement results, the device must be carefully calibrated. It is also possible to draw conclusions about the influence on the temperature measurements taken not only of the product, but also environment. Moreover, the measuring prism itself must also be at room temperature.
There are no special requirements for storing the refractometer. It should be cleaned with a soft damp cloth after the last measurements and placed in dry room so that the measuring eyepiece does not fade. You should not try to disassemble the device and clean it yourself; it is better to contact a specialized service center.
Refractometry is an analytical method based on the phenomenon of light refraction during the transition of rays from one medium to another, which is explained by changes in the speed of light distribution in different environments.
Today, this method of analysis is widely used in many fields: refractometry is often used in pharmaceutical and food analysis, as well as in the study of eyes.
Refractometry in ophthalmology is one of the objective methods for studying the refractive power of the eye - refraction, which is carried out using specialized equipment - an eye refractometer. The refractometry method is used to identify eye diseases such as:
Note! "Before you start reading the article, find out how Albina Guryeva was able to overcome problems with her vision by using...
This research method allows doctors to quickly obtain accurate data about the patient’s eye health. The procedure is possible at any age: both children and adults - this is a definite advantage of the method.
As already mentioned, refractometry is carried out using specialized ophthalmological equipment - refractometers, which come in several types:
Consists of the following parts:
The procedure itself is as follows: a test symbol is introduced into the optical system, which is three vertical and two horizontal stripes. The light beam from the device is directed into the patient's eye under examination and projects onto the retina an image of test symbols, which are referred by the optical system of the eyes to the focal plane of the refractometer. The initial position of the device's optics is a measuring scale with zero values, which are associated with the far points of pure vision of the emmetropic eye. The doctor sees the test symbol through the eyepiece of the device.
With normal refraction of the eye, the two parts of the half-image of vertical and horizontal stripes merge, but in the case of and vice versa, they diverge. The horizontal displacement of the stripes and along the vertical axis indicates.
By turning the device horizontally, the ophthalmologist minimizes the divergence of the bands by installing the device in one of the main meridians. In this way, refraction is measured in a specific meridian. The doctor, by rotating a special ring located near the eyepiece of the device, achieves the merging of the stripes, and the scale of the refractometric device indicates the type and size of the refractive abilities of the eye apparatus. The measurement limit for this type of equipment is from -20.0 to +20.0 diopters, but the accuracy is up to 0.25 diopters.
The most commonly used today are automatic computerized refractometers. The essence of their work is also based on the emission of microscopic beams of infrared rays, which cross the pupil and the refractive medium, are reflected from the fundus of the eye and go in the opposite direction. The device’s sensor reads out the received information, and a special application analyzes the original and newly obtained data, through which the clinical refraction of the eyes is calculated. All results obtained are instantly transferred to the monitor and printed.
The procedure for measuring refraction occurs as follows:
The finished printout contains all the information about the state of refraction of our eyes and their health. And naturally, the results for any patient are of considerable interest. However, not everyone can read a refractogram fluently. How are the indicators deciphered?
The finished printout consists of three columns:
Refractometry values change throughout life. For example, farsightedness is most often detected in a newborn child, but by the age of 20 this anomaly remains in only a third. About 40% of young people have normal refraction, while the rest suffer from myopia. And with age, refraction worsens, which is caused by age-related changes in the lens, at which time patients begin to develop p. Therefore, it is extremely important to undergo periodic examinations in order to promptly prevent the development of eye diseases.
To obtain the most accurate results, before the procedure, the ophthalmologist prescribes a course of atropinization, which the patient undergoes for three days. This procedure consists of daily instillation of an atropine solution twice: in the morning and in the evening. The concentration of the drug is set in accordance with the age group of the subject, but can be changed due to individual factors.
It is strictly forbidden to start using drops on your own, as this can lead not only to false readings, but also worsen eye health. One more important factor The success of the procedure is to give up alcohol a few days before refractometry.
If allergic reaction If you experience atropine, you must immediately notify the treating ophthalmologist and stop instilling the drug.
It is also used during vision correction with glasses or contact lenses.
The device is a complete system for converting and recording infrared radiation. Based on indicators of reflected radiation such as intensity and wavelength, a special program of the device carries out calculations. The decoding results will indicate the refraction (refractive power) of the optical media of the eye.
To understand why research is used in ophthalmology, you should know the structure and basic principles of operation of a refractometer.
They are based on these key points:
There are several medical indications for conducting research using a special automatic analyzer:
Also, research using a refractometer is necessary when conservative methods vision correction. An examination on the device is mandatory when wearing it in order to monitor the progress of treatment.
Refractometry is an outpatient procedure that is performed in a specially equipped office. The examination is carried out in a non-contact manner, therefore it does not require medical personnel preliminary preparation in compliance with the rules of asepsis and antiseptics.
To obtain a reliable result, as well as to eliminate errors, the pupil is first dilated using medicine atropine. It belongs to the pharmacological group of M-anticholinergic drugs and leads to temporary paralysis of the eye muscles that constrict the pupil.
Atropine in the form of eye drops is prescribed 3 days before the intended examination. Eye drops are instilled 2 times a day at approximately equal intervals (morning and evening).
During the procedure, the patient sits on a chair in front of the device, and rests his head against a special stop. The doctor asks you to focus your gaze on the sensors and not move.
After the device starts operating, the sensors emit infrared radiation, which is reflected from the retina of the eye, passes back and is recorded. Duration of the study using automatic refractometer does not exceed two minutes for each eye.
After conducting the examination using an automatic device, it issues a printout that displays the main indicators in the form of letter values and numbers.
They have the following decoding:
The number of indicators depends on the specific model of ophthalmic automatic refractometer that was used for the examination.
The examination, which is carried out using a refractometric device, helps to avoid medical errors and accurately establish the diagnosis. This saves time for the doctor and the patient. And thanks to the non-contact nature of refractometry, it also eliminates physical discomfort for the patient.
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