Stories & Features
Mastering Etendue: The Key to Next-Gen Throughput
May 28, 2026
by
IDEX Health & Science
In optical system design, light is the currency you spend to get meaningful results, but etendue is your spending limit. Many system designers hit a technical wall where simply trying to deposit more laser power or buy a faster camera no longer yields results. This stagnation happens because the system's etendue has already capped how much information can actually be transferred.
To truly overcome these bottlenecks, we must look beyond individual components and consider the etendue conservation of the entire optical train.
What is Etendue and Why Does It Matter?
Etendue (pronounced ay-tahn-doo) is a fundamental property of optics that characterizes how "spread out" the light is in both area and angle. Mathematically, it is the product of the area of the image and the solid angle that the focusing light subtends.
- The Golden Rule of Etendue: In any optical system, etendue can never increase. It can only stay the same or decrease (which means losing light).
In an imaging system, three main components will each have a bearing on the overall etendue: the imaging optics, the sensor, and the illumination system. If any one of these is mismatched to the others, this results in wasted photons, poor image uniformity, and a system with ultimately lower efficiency and throughput.
Where OTS objectives hit the NA–FOV wall, custom designs push etendue further.
Quantifying the Throughput Gap
Throughput is a direct consequence of the relationship between biology, optics, and data needs. When we optimize for higher and matched etendue within the system, the performance gains are measurable:
- Speed Benchmarks: Utilizing a custom 14.18X objective allows for a larger etendue capacity, reaching a throughput of 11.4 mm²/s—which is 6.4x faster than a standard off-the-shelf (OTS) 20X objective.
- Scanning Modalities: For a 15 mm x 15 mm sample, an etendue-optimized TDI line scan can complete the task in approximately 1.2 seconds, whereas traditional "step-and-shoot" methods take roughly 20 seconds.
Proof of Concept: The XPLAN™ CCG Lens Series
The Melles Griot XPLAN™ CCG Lens Series is a prime example of how we provide an etendue-matched service for our customers. While standard OTS objectives are often the pinch point for etendue in an instrument, the XPLAN CCG series is engineered to expand these limits:
- 100% Usable FOV: Standard Gaussian beams are etendue-inefficient, often leaving 35%–70% of a sensor under-illuminated. By matching flat-top beam shaping to the Etendue of the XPLAN CCG Lens Series, we ensure every pixel is utilized.
- Diffraction-Limited Performance: A high-etendue system is only useful if the quality of the focus remains high. The XPLAN CCG series ensures resolution remains consistent from the center to the very edge of the field, eliminating the data loss typically caused by field curvature or other optical aberrations.
- Scaling Power with Speed: As imaging speed increases, the demand for irradiance rises. We match high-power laser engines to the XPLAN CCG series, ensuring the system isn't bottlenecked by power or geometry.
The Power of Collaboration: Melles Griot Optical Systems
Overcoming these challenges requires a holistic view of the optical path. By leveraging the expertise of Melles Griot Optical Systems from IDEX Health & Science, we provide a level of collaborative engineering that goes beyond simple component selection.
We don't just sell lenses; we provide the engineering partnership to align your system's etendue from source to sensor. By prioritizing etendue optimization through integrated Melles Griot solutions, we help you move from standard imaging to the high-throughput performance required for the future of biotech.
