Refractive Index – RI Measurement of Solids & Films

Refractive Index Solids Films Kit

RI Measurement of Solids and Films.

RI measurement of solids and semi-solids is useful in labs for monitoring quality to insure consistency of transparency, pigmentation, or batch quality. RI might be measured on incoming materials or finished products. Highly accurate measurements are possible with the right refractometer and a method to measure the material.

Instrument: J457 Refractometer with Solid Measurement Kit

Application:  Measuring RI of solids, Films, Plastics, Resins

Material Applications: Films, glass, plastics, resins, tapes, semi-solids, silicones.

The Rudolph J457 combined with a Rudolph Research Solid measuring kit may be utilized as follows to measure the RI of many films, sheet goods, and semi-solids.

You may view a short demonstration of measuring RI of solids below or contact us for a more detailed explanation.

Refractometer Video, RI Measurement of Solids, Films, and Semi-Solids

Refractive Index – RI Measurement of Solids & Films – Video Transcript.

To prepare to measure a Solid Sample the following are required. Prepare a disc shaped sample 14mm in diameter using the hole punch supplied with the solid kit

Used as an example is a sample punched from a plastic sheet. Any solid that can be prepared to a 14 mm disc with a smooth face can be measured. The thickness is not a concern however the sample must have a flat, optical face.

If the sample is soft such as a silicon the sample can be placed right on the prism. If the material is more ridged such as the plastic sample we are using you will need an “Optical Coupling Fluid” The fluid you use must have a higher R/I than the sample you are measuring.

The solid measurement kit is designed to fit the Rudolph J457 Refractometer.
The J457 is rated to the 5th decimal for liquids. The accuracy for solid materials will depend on the sample type and preparation.

The J457 Refractometer from Rudolph Research with the solid measurement kit can measure a wide range of solids. This is useful in applications where the RI of a solid is important to maintain quality control and when matching like materials.

Download this information as a PDF: RI Measurement of Solids and Films

For additional information see the Rudolph Research Refractometer Product Line




  • Peter Marriott
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  • Peter Marriott has spent over 25 years in the laboratory instrument industry. Educated at Monash University and RMIT in Australia, Peter joined Rudolph Research in 1999. His main focus has been making scientific measurement techniques easy to implement in real, often non-scientific, world.