A digital refractometer is a device used to measure the refractive index of a liquid or solid sample. It is a useful tool for measuring the concentration of a solution, such as the sugar content of a fruit juice or the alcohol content of a beer. Digital refractometers are relatively easy to use and can be found in many laboratories and research facilities. Here is how to make a digital refractometer:

1. Gather the necessary materials. You will need a light source, a lens, a sample holder, a digital display, and a power source.

2. Assemble the components. Place the lens in the sample holder and attach the light source to the holder. Connect the digital display to the power source.

3. Place the sample in the sample holder. Make sure the sample is evenly distributed and that the light source is shining through it.

4. Turn on the power source and adjust the digital display to the desired refractive index.

5. Measure the refractive index of the sample by reading the digital display.

6. Repeat the process for different samples to get an accurate reading.

Making a digital refractometer is a relatively simple process that can be done with basic materials. With a digital refractometer, you can quickly and accurately measure the refractive index of a sample.