MEMS “Digital Light Switch” Technology for Compact NIR and SWIR Spectrometers

Near-infrared (NIR) and short-wave infrared (SWIR) spectroscopy are rapidly moving beyond laboratory environments. These technologies are increasingly being integrated into industrial inspection systems, portable instruments, and even field-based applications such as agriculture and food quality analysis.

As the demand for compact sensing tools grows, new spectrometer architectures are emerging to replace larger traditional systems. One particularly promising approach combines micro-electromechanical systems (MEMS) with programmable optical control, enabling miniature spectrometers capable of accurate and flexible spectral analysis.

The Shift Toward Portable Spectroscopy

Spectroscopy has long been used to analyse materials by measuring how they absorb or reflect light at different wavelengths. In the NIR and SWIR regions of the spectrum, these measurements are especially useful for identifying chemical composition, moisture levels, and organic materials.

Applications include:

• Agricultural crop monitoring

• Food quality and contamination detection

• Pharmaceutical analysis

• Industrial process monitoring

• Environmental sensing

Historically, instruments capable of performing these measurements were relatively large and expensive. However, advances in optical engineering and MEMS technology have made it possible to significantly reduce both the size and cost of spectroscopic devices while maintaining reliable performance.

Introducing the Digital Light Switch Concept

One modern solution for miniaturised spectroscopy is the digital light switching approach, which is often implemented using Digital Light Processing (DLP) technology. In these systems, arrays of microscopic mirrors—fabricated using MEMS techniques—act as programmable optical switches.

Each mirror can tilt to direct light either toward a detector or away from it. By selectively controlling these mirrors, specific wavelength bands can be measured without the need for a large detector array.

This approach effectively replaces traditional mechanical scanning mechanisms or large photodetector arrays with a digitally controlled optical filter.

How the Technology Works

The typical architecture of a digital light switching spectrometer includes several key components:

1. Broadband light source – illuminates the sample being analysed.

2. Diffraction grating – separates incoming light into its constituent wavelengths.

3. MEMS mirror array (DLP device) – selectively directs chosen wavelengths.

4. Single-pixel detector – records the intensity of selected spectral components.

The grating disperses the light across the MEMS mirror array. By tilting individual mirrors, the system directs specific wavelength bands onto the detector, allowing the instrument to measure spectral information sequentially or selectively.

This digital selection process enables high flexibility and efficient use of detector hardware.

Advantages of MEMS-Based Spectrometers

Digital light switch spectrometers offer several advantages compared with traditional designs:

Compact Form Factor

MEMS components are extremely small, allowing the optical system to be miniaturised for handheld or embedded instruments.

Reduced System Cost

Using a single detector instead of a large detector array lowers overall component costs.

Improved Measurement Efficiency

Because only relevant wavelengths can be selected for analysis, measurement time and processing requirements can be reduced.

Greater Robustness

Solid-state MEMS mirror arrays eliminate many mechanical scanning parts, improving reliability in industrial or field environments.

Enabling New Applications

As spectrometer size and cost decrease, new applications become practical. Portable instruments can now be used directly in production lines, agricultural settings, or inspection points rather than requiring samples to be transported to laboratories.

Examples include:

• Real-time monitoring of food quality during processing

• Rapid identification of raw materials in pharmaceutical manufacturing

• Portable crop analysis tools for farmers

• Inline industrial process monitoring

These developments demonstrate how digital light switching technology is helping spectroscopy transition from specialised laboratory equipment into widely deployable sensing tools.

The Future of Compact Spectroscopy

The continued evolution of MEMS optics and programmable photonics is likely to further expand the capabilities of miniature spectrometers. As performance improves and integration increases, these systems may eventually be embedded into everyday devices and smart sensing platforms.

By combining programmable optical elements with advanced detectors and signal processing, MEMS-based digital light switch spectrometers represent an important step toward smaller, smarter, and more accessible spectroscopy solutions.

For more information on Is a MEMS-based digital light switch the answer to compact NIR and SWIR sensing? talk to AP Technologies Ltd