Surreal digital illustration of varifocal lens focusing on landscape.

Focus Like Never Before: How Varifocal Lenses Are Changing 3D Surface Profiling

Lena Kashyap in Tech & Innovation August 2025 • 5 min read.

"Explore the cutting-edge technique of 3D surface profiling using varifocal lenses and focus stacking, and discover how this innovative method is set to revolutionize precision measurement across industries."

In today's high-tech world, the ability to accurately measure surfaces in three dimensions is more crucial than ever. From ensuring the quality of microchips to studying the intricate textures of biological samples, precise surface profiling is essential across numerous fields. Traditional methods, however, often fall short, proving either too slow, too damaging, or simply inadequate for the complex surfaces encountered in modern science and industry.

Enter varifocal lens technology—a game-changing approach that's revolutionizing 3D surface profiling. By combining varifocal lenses with focus stacking techniques, researchers are achieving unprecedented levels of speed, accuracy, and versatility. This innovative method promises to overcome the limitations of existing technologies, opening up new possibilities for quality control, research, and development.

This article explores the exciting advancements in 3D surface profiling using varifocal lenses. We'll break down the science behind this technology, examine its applications, and discuss its potential impact on various industries. Whether you're a seasoned engineer, a curious scientist, or simply interested in the latest technological innovations, get ready to discover how varifocal lenses are changing the way we see the world, one surface at a time.

The Science of Varifocal Lens-Based Profiling

Surreal digital illustration of varifocal lens focusing on landscape.

At its core, varifocal lens-based 3D surface profiling combines two powerful techniques: varifocal lenses and focus stacking. A varifocal lens is a special type of lens whose focal length can be rapidly adjusted electronically. This allows the system to capture images of a sample at different depths without physically moving the lens or the sample. Focus stacking is a computational technique that combines multiple images taken at different focal depths to create a single image with an extended depth of field. This results in a sharp, clear image of the entire surface, even if it has significant variations in height.

The process begins by using the varifocal lens to capture a series of images at slightly different focal distances. These images are then fed into a computer, where a focus stacking algorithm identifies the sharpest areas in each image. These sharp areas are then combined to create a composite image with a large depth of field. In many systems, a high-pass filter is applied to the source images to enhance the performance of the focus algorithm by reducing blurriness and improving the identification of in-focus pixels. The focal power corresponding to the in-focus pixels is recorded, creating a diopter index that serves as a 3D map of the surface.

Here are some key benefits of this approach:

Speed: Varifocal lenses can rapidly adjust their focal length, allowing for fast image acquisition.
Non-Destructive: Optical measurements prevent damage to delicate samples.
Accuracy: Computational techniques enhance precision and reduce errors.
Versatility: Adaptable to various sample types and sizes.

One critical aspect of this technique is the algorithm used to determine the sharpness of the images. A common approach is to use the absolute gradient algorithm, which calculates the rate of change in pixel intensity. Sharper images will have higher gradient values. To prevent the algorithm from being misled by noise or areas lacking surface detail, a high-pass filter is often applied to the source images. This filter emphasizes the high-frequency components of the image, making it easier to identify the sharpest pixels.

The Future of Surface Measurement

Varifocal lens-based 3D surface profiling represents a significant advancement in the field of metrology. Its ability to quickly and accurately measure complex surfaces opens up a wide range of possibilities across various industries. As the technology continues to evolve, we can expect to see even more innovative applications emerge, further solidifying its role as a key tool for quality control, research, and development. From ensuring the reliability of semiconductors to advancing our understanding of biological systems, varifocal lenses are poised to shape the future of surface measurement.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1109/i2mtc.2018.8409820, Alternate LINK

Title: Surface Profiling Measurement Using Varifocal Lens Based On Focus Stacking

Journal: 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC)

Publisher: IEEE

Authors: Chen-Liang Fan, Chun-Jen Weng, Yu-Hsin Lin, Pi-Ying Cheng

Published: 2018-05-01

Everything You Need To Know

What is varifocal lens technology and how does it work in 3D surface profiling?

Varifocal lens technology combines varifocal lenses with focus stacking to achieve rapid and precise 3D surface profiling. Varifocal lenses rapidly adjust focal length electronically, capturing images at different depths without physical movement. Focus stacking then combines these images, taken at different focal depths, to create a single, sharp image with an extended depth of field, effectively mapping the entire surface. This approach overcomes the limitations of traditional methods by providing speed, accuracy, and versatility. Missing from this answer is how the varifocal lens is controlled to move to each focal point. Additionally the software is important for focus stacking.

How does the focus stacking algorithm work in varifocal lens-based 3D surface profiling, and what role does a high-pass filter play?

In varifocal lens-based profiling, images captured at different focal distances are processed using a focus stacking algorithm. This algorithm identifies the sharpest areas in each image and combines them to create a composite image with a large depth of field. A high-pass filter is often applied to the source images to enhance the performance of the focus algorithm by reducing blurriness and improving the identification of in-focus pixels, leading to a diopter index that acts as a 3D map. The sharpness is often determined by using the absolute gradient algorithm. A missing part of this answer would be the implementation of a machine learning algorithm to increase precision.

What are the key advantages of using varifocal lens-based 3D surface profiling, and what are its limitations?

Varifocal lens-based 3D surface profiling offers several key benefits: speed due to rapid focal length adjustment, non-destructive measurements that prevent damage to delicate samples, accuracy through computational techniques that reduce errors, and versatility, making it adaptable to various sample types and sizes. While these advantages are significant, the initial setup cost and the complexity of the algorithms can be limitations. Further development is expected to continue to solidify its role in quality control, research, and development.

How does the absolute gradient algorithm work in varifocal lens-based 3D surface profiling?

The absolute gradient algorithm calculates the rate of change in pixel intensity to determine image sharpness in varifocal lens-based 3D surface profiling. Sharper images exhibit higher gradient values. This is used to identify the sharpest image to build the stack. Missing is a description of other algorithms and their performance impact.

What is the future impact of varifocal lens-based 3D surface profiling on industries like semiconductors and biomedicine?

Varifocal lens-based 3D surface profiling is poised to significantly impact industries requiring precise surface measurements, such as semiconductors and biomedicine. Its ability to quickly and accurately measure complex surfaces can enhance quality control, accelerate research and development, and improve the reliability of products. As the technology evolves, further applications are expected to emerge, solidifying its role as a key tool for various industries. This method is more versatile and often faster than older techniques, but the accuracy might not be ideal for every use case.