Single-photon sensitive imaging

Deep tissue imaging

The optical imaging system with a 1310nm probe beam and unique time-gated detection is exceptionally well-suited for deep tissue imaging. By utilizing second optical tissue window, which at wavelength 1310nm, it can penetrate deep into biological tissues with minimal scattering, allowing researchers and medical professionals to visualize and study internal structures, such as blood vessels, tumors, and organs. The time-gated detection enhances image quality and reduces background noise, making it an invaluable tool for non-invasive diagnostics, medical research, and the development of novel therapies.

Chip Inspection

With an alternative ultra narrow pulse light, this optical imaging system can find a crucial application on non-destructive defect inspection for semiconductor chips. Its ability to operate at 1310nm enables it to analyze microelectronics and integrated circuits with high precision. The longer wavelength reduces the risk of damaging sensitive components while providing detailed insights into chip features. The time-gated detection further enhances the system's capability to identify defects, inspect solder joints, and characterize surface structures, ensuring the reliability and performance of electronic devices produced in the semiconductor industry.

Skin cancer and tumor diagnosis

The optical imaging system's unique capabilities make it a promising tool for skin cancer and tumor diagnosis. Tissues have distinct optical properties, and by harnessing the system's 1310nm probe beam and advanced algorithms, it can differentiate between healthy and abnormal tissue with precision. This technology has the potential to revolutionize pathology by offering non-invasive and rapid diagnostic insights.

Skull Imaging

The optical imaging system's ability to penetrate opaque media is particularly valuable for skull imaging. It can provide detailed images of the internal structures of the skull without invasive procedures. With its sensitive detector, it becomes possible to visualize and study the brain, blood vessels, and other critical components within the skull. This non-invasive approach is especially beneficial for medical applications, such as monitoring brain injuries, assessing cerebral blood flow, and aiding neurosurgical planning, all without the need for surgery or radiation exposure.

QCI’s approach is distinctive in that it utilizes a second optical window as probe light (1310 nm) and combines optical nonlinear techniques with a single photon sensitive detector. It will be a new system that will overcome most of the existing commercial imaging technology limitations, like the nuclear or high energy radiation, less penetration, long acquisition time, large footprint, etc.

Optical imaging techniques are generally preferred to nuclear or high energy radiation techniques due to their superior reproducibility, higher spatial resolution, and higher overall sensitivity. The latter techniques, however, are still widely utilized due to the ability of high energy radiation to penetrate deeper into regions of interest. For example X-ray and CT. 

Besides, the dominant mechanisms which limit the applicability of optical imaging techniques are the absorption and scattering of light primarily by water molecules inside tissues. Many of the currently developed imaging technologies operate at the 1310 nm wavelength due to a local minimum in water absorption around 1300 nm. While absorption by water molecules is decreased around 1310 nm and scattering processes are pronounced (as compared to 1st near infrared imaging window), the detector sensitivity for near infrared wavelength is limited due to higher dark noise. To overcome this problem by improving the sensitivity of imaging techniques, single photon upconverted imaging has been employed.

The prototype device which was produced at QCi uses 1550 nm picosecond laser pulses to selectively upconvert the backscattered photons in wavelength 1310 nm according to their spatiotemporal modes via sum-frequency generation in a 𝜒2  nonlinear crystal, which are then detected by an electron-multiplying CCD with photon sensitive detection. As such, it achieves sub-millimeter depth resolution, exceptional noise suppression, and high detection sensitivity. Our results show that it can accurately reconstruct the surface profiles of occluded targets placed behind highly scattering and lossy obscurants of 14 optical depth (round trip), using only milliwatt illumination optical power. In addition, the imaging depth in the air can reach 18 cm, while the current OCT imaging is only 2 cm.