Short Wave Infrared, or SWIR, is an evolutionary step toward our ability to attain more data that can be leveraged as useful information. Scientists from around the world all agree that cost-effective SWIR imagers can extend their research capabilities dramatically through expanded and deeper analysis of various materials. Going beyond visible wavelengths to the 400-700nm range opens a broad new world of research and opportunity to make a difference in the world we live.
InView’s reasonably priced SWIR imagers are easily adapted to most microscopes through a standard interface design enabling far more researchers access to this incredibly useful wavelength regime. SWIR research is no longer an exclusive area due to costs and technical challenges. With connectivity via Ethernet and USB protocols and our simple to use software application, CompressView, virtually any scientist can be up and running experiments quickly and without having to learn a new system. The higher energy IR can excite molecular overtones and harmonics so materials exhibit distinctive image contrast behaviors in the SWIR depending on their composition. The band gap of many important crystalline materials, most notably silicon, are in the NIR and so they are transparent in the SWIR. This fundamental perspective is enabling scientists to minimize wavelength and thus maximizing lateral resolution while maintaining these fundamental phenomena.
Semiconductor Example: Backside IC Imaging
Because silicon is transparent to the SWIR it is possible to image or “See through” through the backside of a wafer to the metal structure. Functional die may now be probed and viewed to assist in inspection and defect detection.
The transparency of many semiconductors in the SWIR combined with high lateral resolution make SWIR ideal for IC inspection activities: wafer defect review, crystal stress measurement, IC defect review, Ball-Grid Array (BGA) bonding view, MEMS and Wafer-Level Packaging (WLP) inspection and alignment, wafer-level optical interconnect, optical communication, Essentially, a deep probe analysis and defect detection and microchip inspection (packaged or unpackaged).
Invisible Beam Alignment and Characterization
An invisible laser beam (1.55 µm) is aligned to a silicon waveguide structure using a SWIR imager. The left image shows SWIR laser light that is scattered as it moves around the submicron waveguide. The laser is off in the second image and the tapered entrance and exit channels can be viewed. Align beams from invisible sources such as lasers and LED’s and perform laser beam profiling and the general study of gaseous lasers.
Medical Applications: Human Tissue Analysis
There are vast areas which SWIR imaging within the medical community is making in-roads. Making novel dental, epidermis, and ocular tissue inspections are just a few commonly being explored today. Because human tissue is of relatively high transmission in the SWIR, it is an excellent wavelength range for analysis and can enable optical coherence tomography (OCT) applications beyond current wavelengths as well thus taking advantage of SWIR’s good cell penetration and low sample heating.
Other areas include:
- Digital pathology Tissue diagnoses
- Bilological sampling
- Measure fluorescence, perform novel cellular imaging
Use an InView SWIR imager where composition discrimination and high resolution are of interest. Make measurements of areal concentration, morphology, porosity, and grain sizes.
Silicon crystal defects, saw and polish defects, poor lead contacts, and thin film PV processing variation can be seen through Electroluminescence and Photoluminescence (EL & PL) imaging techniques. The emission peaks of PV cells are typically centered in the SWIR making a SWIR imager the optimal choice. Specifically within PV analysis and testing, engineers check powders/mixtures for composition, contamination, and moisture content.
Food/Plant Inspection: Unseen spoilage, insects, and disease
Detect unseen bruising in fruits, moisture levels and indications of plant diseases invisible to the naked eye. Detect the presence of small insects not apparent due to small size and protective coloration. Non-contact analysis of foodstuffs (quality, degree of ripeness, pests or mold)
Art and Documentation: Examination & Forgery Detection
Using SWIR camera, researchers can identify alterations, erased markings or overwriting of restorations on certain inks, removals by abrasion or bleaching and other forgery methods. Though intentionally unseen in the visible many changes are apparent in the SWIR due to the unique hyperspectral behavior of materials.
High Temperature/ Thermal Imaging
Thermal emission imaging for heat sources over 150°C is possible in applications such as glass processing, in-situ chemical reaction monitoring, and processing of molten metals. The use of lower cost glass lensing (vs. exotic materials of MW and LW infrared lenses) can lead to favorable cost of ownership.