---
title: "Product Quality Testing: Monitoring Fluid Concentrations Using the Index of Refraction"
description: Our latest experiment uses non-contact measurement technology with the saline solution to create an optical thickness measurement that correlates to the refractive index.
---

[Blog | Lumetrics ](https://www.lumetrics.com/blog)

# [Product Quality Testing: Monitoring Fluid Concentrations Using the Index of Refraction](https://www.lumetrics.com/blog/monitoring-fluid-concentrations-using-index-of-refraction)

 Written by [Kristin Hart Daly](https://www.lumetrics.com/blog/author/kristin-hart-daly) | May 11, 2022

## Improving Speed and Precision of Concentration Monitoring with Non-Contact Measurement

For manufacturers of fluid-based products like saline, product quality is absolutely essential. In [healthcare](https://www.lumetrics.com/applications/medical-device-thickness-measurement), saline flushes wounds, delivers medications, treats [ophthalmic](https://www.lumetrics.com/applications/ophthalmic-metrology-applications) conditions, and much more; measuring the concentrations of sodium chloride ensures product stability, reliability, and performance for expected patient outcomes.

Non-contact, non-destructive measurement technologies like the [OptiGauge II](https://www.lumetrics.com/capabilities-products/non-contact-thickness-measurement-systems/optigauge-ii) provide manufacturers with the speed and precision they need to monitor concentration levels. As fluids mix, the OptiGauge II continually measures the [refractive index](https://www.lumetrics.com/blog/liquid-refractive-index-measurement) of the mixture in real-time, alerting operators to fluctuations that may bring the fluid out of spec. By performing precise measurements (at the submicron level) throughout the process, manufacturers can perform stringent quality control checks reliably and accurately, which ultimately results in continued patient safety.

In this experiment, Lumetrics’ David Compertore demonstrates how the OptiGauge II passes a beam through the saline solution, creating an [optical thickness measurement](https://www.lumetrics.com/blog/optical-thickness-measurement-of-multilayer-film) that correlates to the refractive index, proportional to the salt’s concentration.

##### Follow Dave through the process, check out the specs, and request a demonstration.

 

 

### Want to explore how our non-contact thickness measurement systems pair with your application? Request a demo! 

If you have questions about our products or want to learn more about our metrology capabilities, [connect with an engineer](https://www.lumetrics.com/engineering-support)! 

 

[View full post](https://www.lumetrics.com/blog/monitoring-fluid-concentrations-using-index-of-refraction)

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