Blog

A drop of fruit juice, half a drop of honey, or even car coolant—within just a few seconds, this palm-sized instrument can reveal their concentration secrets. Among numerous testing instruments, the handheld refractometer holds an important position thanks to its unique advantages. Whether it's testing in laboratories, quality control in industrial production, or small inspections in daily life, it can perform brilliantly. Now, let's delve into the principles, applications, and usage methods of the handheld refractometer.   I. Working Principle: Ingenious Application of Light Refraction Phenomenon   Light travels at different speeds in different transparent media, and when it passes from one medium to another, its direction of propagation changes—this is the phenomenon of light refraction. The handheld refractometer makes clever use of this property.   Solutions with different concentrations have different refractive indices. When light passes through the solution to be tested, the refraction angle changes with the concentration. The handheld refractometer captures these changes in refraction angle through its internal optical system, and then converts the refraction angle into directly readable concentration values (such as sugar content, salinity, alcohol concentration, etc.) based on pre-set corresponding relationships. The blue-white boundary line we see in the eyepiece is exactly the light-dark junction formed by different refracted light rays, and the position of this boundary directly corresponds to the concentration of the solution.    II. Versatile Applications: A Quality Guardian Across Multiple Fields   1. Sugar Content Measurement: The measurement of sugar content (Brix) is the most classic application of handheld refractometers. During the fruit harvest season, farmers can use it to quickly determine the sugar content of fruits such as grapes, apples, and watermelons to judge the optimal picking time. Juice factories rely on it to monitor the concentration in the production line—with just one or two drops of sample, results are available in seconds, preventing sweetness imbalance in entire batches of products. For example, the RHB-32ATC sugar refractometer can measure sugar content in the range of 0-32% with an error of only ±0.2%, making it suitable for most fruit farmers and juice manufacturers.   2. Industrial Production: The RHB series of handheld refractometers can be used to measure the concentration of various industrial solutions, such as cutting fluids and grinding fluids. In industrial production, the stable concentration of cutting fluids and grinding fluids is crucial to ensuring processing quality. The emergence of handheld refractometers not only ensures the stability of the processing process but also avoids raw material waste caused by improper concentration, significantly reducing the comprehensive production cost. It is a practical tool in industrial processing for guaranteeing production efficiency and product quality.   3. Salinity Detection: Precise control of salinity is crucial in the production of pickled foods, seafood processing, and seasoning manufacturing. In the case of pickled vegetables, appropriate salinity ensures their flavor and prevents spoilage. Handheld refractometers can quickly detect the concentration of brine, ensuring the smooth progress of the production process. In mariculture, salinity is related to the survival of fish. Salinity refractometers (such as the RHS-28ATC) can measure salinity in the range of 0-28%, helping farmers adjust the salinity of water bodies.   4. Honey Testing: The core indicator of honey quality—moisture content—is calculated using a refractometer. Professional honey refractometers (such as the RHB-90ATC) can display sugar content, Baume degree, and moisture content simultaneously. When the moisture content of honey exceeds 20%, it is prone to fermentation and deterioration. Therefore, beekeepers need to ensure that the measured value is within the safe range of 20% before capping.   5.Alcohol Concentration Detection: In the brewing industry, alcohol concentration is a crucial parameter for measuring wine quality. From the fermentation process to the testing of finished products, monitoring alcohol concentration is indispensable. Handheld refractometers can quickly measure the alcohol concentration in fermentation broth, helping brewers judge the fermentation progress, adjust fermentation conditions in a timely manner, and ensure the quality of the wine.     For some beverages that require alcohol content control, such as pre-mixed cocktails, handheld refractometers can accurately detect their alcohol concentration, ensuring that the products meet relevant standards and consumer needs.     In industrial fields, alcohol concentration detection is also required in certain production processes that use alcohol as a raw material. For example, in cosmetics production, alcohol is often used as a solvent, and its concentration affects the performance and stability of products. Handheld refractometers can provide rapid concentration detection support for the production process.     6. Battery Fluid and coolant Detection: The concentration of battery fluid has a significant impact on battery performance and service life. Taking lead-acid batteries as an example, measuring the specific gravity of battery fluid (related to concentration) with a handheld refractometer can determine whether the battery's charging and discharging status is normal, detect potential battery problems in time, and ensure the stable operation of the battery in various devices. For instance, the RHA-200ATC can measure the specific gravity of battery fluid in the range of 1.100-1.400; if the measured value is too low, it indicates that the battery needs to be charged or replaced.     Ethylene glycol and propylene glycol are the main components of automotive coolant, and their concentration determines the freezing point. The concentration of propylene glycol or ethylene glycol must be maintained within an appropriate range to effectively exert the cooling effect, prevent equipment overheating, and ensure it operates in the optimal working state.   III. Usage Method: Accurate Measurement in Simple Steps     1. Preparation   First, ensure that the prism surface of the handheld refractometer is clean and free of impurities. You can gently wipe the prism with a soft flannel or special wiping paper to avoid scratches. If it is the first time to use or has not been used for a long time, calibration is required. Calibration method: Drop a few drops of distilled water onto the prism, close the cover, point the instrument at a light source, and adjust the eyepiece to make the scale in the field of view clear. At this point, the light-dark boundary line should align with the 0 scale. If not, use a special screwdriver to adjust the zero adjustment screw until they align. After calibration, wipe off the distilled water drops.     2. Measurement process   Open the cover, use a dropper to take a small amount of the solution to be tested (such as fruit juice, salt water, alcohol solution, battery fluid, etc.), and drop 1-2 drops onto the prism surface. Ensure the solution covers the prism evenly without any bubbles.   Gently close the cover to prevent the solution from spilling or creating new bubbles. Point the light inlet of the instrument at a bright light source (but avoid direct sunlight), put your eye close to the eyepiece for observation, adjust the eyepiece diopter ring to make the scale clear, and read the scale value corresponding to the light-dark boundary line—this value is the concentration of the solution to be tested. If the instrument has a temperature compensation function, the measurement result will be automatically corrected to the concentration value at the standard temperature; if there is no temperature compensation function, the reading needs to be corrected according to the temperature correction table and the ambient temperature during measurement to obtain the accurate concentration.     3. Cleaning and storage   After measurement, immediately use a flannel or wiping paper to gently wipe off the residual solution on the prism surface and the cover, then dry them with a clean, soft cloth. Store the instrument properly in a dry, clean storage box to avoid collision and moisture, so that it can be used next time.

The gemological refractometer is an optical tool used to measure the refractive index of gemstones, a key property for identifying and verifying them. In this article, we explain what a refractometer is, its main applications,how to use one, and how to choose the right one for your needs. What is a Gemological Refractometer?           The gemological refractometer, or simply gem refractometer, is an essential instrument for identifying and analyzing gemstones. It measures the refractive index (RI) of a gem, one of the most reliable properties for distinguishing different materials. Each gemstone bends light in a specific way, expressed as its RI value and related optical behaviors. With this device, users can determine whether a stone is singly or doubly refractive, uniaxial or biaxial, and can calculate its birefringence. By comparing these measurements with known reference data, users can accurately identify a gem and determine whether it is natural or synthetic. Reliable RI testing ensures correct valuation and builds trust in the gemstone trade.   Gemological refractometers come in slightly different materials, shapes, and sizes, but their main parts and functionality are largely consistent across manufacturers and brands. Using our RHG-181 gem refractometer as an example, the main components and their functions are shown below. How to Use a Gemological Refractometer Properly? To properly use a gem refractometer, you will need four things: a gem to be tested, the refractometer, RI fluid (or contact fluid), and a light source. Our product comes with everything except for the gem.    Step 1: Preparation    1. Place the refractometer on a flat, even surface with the upper cover (1) open.    2. Apply a small drop of RI fluid onto the prism. The drop should be around 1 to 2 mm in diameter.    3. Carefully place the gemstone onto the prism, taking care not to scratch the glass.    4. Direct the light source into the sodium light filter (3) on the back of the refractometer.    Note: For refractometers without a sodium light filter, a sodium light source with a precise wavelength of 589 nm should be used for the most accurate results. The RHG-181 gem refractometer includes a sodium color filter, which means any white LED light can be used. The RI fluid is toxic and must be handled with care. We recommend using a dropper, which is included in our product packaging.   Step 2: Observation Look into the eyepiece — the field of view should be brightly lit. You will see an RI scale ranging from 1.30 to 1.81. One or two shadow edges may appear, which are faint dividing lines between the light and dark areas. The point where the shadow edge intersects the scale is your RI reading. You may need to adjust the position of your head to see the shadow edges more clearly. To identify your gemstone, you should then ask the following questions in order:   1. Is the gem singly or doubly refractive? Slowly rotate the gemstone in any direction while continuing to look through the eyepiece. If you see only one shadow edge and it does not move, the gemstone is singly refractive. If at any point you see two shadow edges that separate and come together again as you rotate, the gemstone is doubly refractive. Note: For doubly refractive stones, the shadow edge at the higher RI value is typically fainter than the lower-RI edge. When the two edges are very close together, they can be hard to distinguish, so look carefully.     For singly refractive gemstones, your work is complete. Simply record the RI value of the stone and compare it with the reference data sheet (provided at the end of this article) to identify the gem. RI values are typically noted to three decimal places, while the refractometer scale only provides two. Therefore, you should make your best estimate of the third decimal place. For doubly refractive gemstones, we still need to determine whether the stone is uniaxial or biaxial, and then calculate its birefringence.   2. Is the gem uniaxial or biaxial? After confirming that a gemstone is doubly refractive, the next step is to determine whether it is uniaxial (one optic axis) or biaxial (two optic axes). Slowly rotate the gem while looking through the eyepiece, and observe the movement of the two shadow edges: If only shadow edge remains nearly stationary, while the other edge may shift slightly, then your gemstone is uniaxial. If both shadow edges shifts irregularly as you rotate the gem, and the seperation between the two edges changes quite noticably, then your gem is biaxial.