Researchers have used the centuries-old idea of pinhole imaging to create a high-performance mid-infrared imaging system without lenses. The new camera can capture extremely clear pictures over a large range of distances and in low light, making it useful for situations that are challenging for traditional cameras.
“Many useful signals are in the mid-infrared, such as heat and molecular fingerprints, but cameras working at these wavelengths are often noisy, expensive or require cooling,” said research team leader Heping Zeng from East China Normal University. “Moreover, traditional lens-based setups have a limited depth of field and need careful design to minimize optical distortions. We developed a high-sensitivity, lens-free approach that delivers a much larger depth of field and field of view than other systems.”
Writing in Optica, the researchers describe how they use light to form a tiny “optical pinhole” inside a nonlinear crystal, which also turns the infrared image into a visible one. Using this setup, they acquired clear mid-infrared images with a depth of field of over 35 cm and a field of view of more than 6 cm. They were also able to use the system to acquire 3D images.
