A new easily portable digital holographic microscope could broaden a range of applications by making precision 3D measurements accessible through smartphone-powered technology.
The low-cost microscope features capabilities that could assist in everything from near-patient testing to educational and scientific uses.
By digitally recreating 3D information about objects and environments with holographic technology, holographic microscopes allow researchers to make highly precise measurements of not only the surfaces of objects, but also their internal structures.
Currently, digital holographic microscopes are less than optimal for field use, since they can only function by relying on elaborate technologies that normally require conventional desktop computers to make calculations.
That is all about to change with the development of a new, simpler optical system by researcher Yuki Nagahama from the Tokyo University of Agriculture and Technology and her team, which employs 3D printing capabilities and smartphone-based calculations to create what Nagahama says will be a new microscope that is “inexpensive, portable and useful for a variety of applications and settings.”
Holographic Reconstruction in Near Real-Time
The new holographic microscope is capable of functioning in close to real time, according to a new paper the team published in the journal Applied Optics.
Similar to normal images captured with smartphone cameras, once a microscopic image is produced by Nagahama’s system, users can “pinch” the rendering to zoom in and view portions of the reconstruction in greater detail.
Nagahama says that the new application could be useful in a wide range of medical applications, particularly in regions where such technologies are currently inaccessible.
Additional uses for the new holographic microscope include research efforts in the wild where precision 3D renderings of microscopic objects have previously never been possible.
Fun-Sized Holographic Microscopy
For Nagahama, the concept for this new holographic application drew from her personal experiences.
“When I was a student, I worked on portable digital holographic microscopes, which initially used laptops as the computing system,” Nagahama said in a statement.
However, as more and more smartphone apps extended the normal functions of mobile phones to enable novel capabilities, Nagahama began looking at how they might also serve as the computers for powering applications in a wide range of areas, “which ultimately shaped the development of this microscope.”
Normally, digital holographic microscopes detect interference patterns that emerge between light scattered from the sample in question and a reference beam produced by the device. Based on this data, the hologram is reconstructed using 3D information that can measure a sample, and in the case of holographic microscopy, even beneath the object’s surface.
The new device is not the first smartphone-based holographic microscope, and while others exist, Nagahama’s is the first to feature almost real-time reconstruction capabilities by relying on what is called band-limited double-step Fresnel diffraction, which enables fast calculations based on the diffraction patterns it observes. The faster process is made possible by greatly reducing the amount of data required for collection during use.
Lightweight but Powerful
The new system is housed within a lightweight container, which includes both the microscope’s optical system and the 3D printer. Holograms are reconstructed using an Android application designed specifically for use with the new technology, which employ the image sensor of a camera connected to the device via USB. Finally, the resulting image is displayed on the smartphone screen.
Right now, the new microscope can reconstruct holograms at frame rates of up to 1.92 frames per second. Going forward, Nagahama and the team plan to improve the new application with help from deep learning, which they hope will limit the production of secondary imagery that are unintended artifacts which occasionally arise from the holographic reconstruction process.
The team’s findings appeared in the recent study, “Interactive zoom display in a smartphone-based digital holographic microscope for 3D imaging,” published in Applied Optics on August 23, 2024.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.