BACKGROUND:  There are many applications for solutions to the fundamental optical problem of detecting a light source and measuring its spatial position. Several methods are known to retrieve the spatial position of one or more optical features. The simplest method, direct imaging, is constrained by the diffraction limits and the lack of field depth limiting the measurable volume. Interferometric methods are superior to imaging ones for retrieving the depth position of a light point, but are much more elaborate methods.

INNOVATION:  Researchers at UCLA have developed an improved methodology for determining positions of optical features that is simpler and more robust than existing methods. The method uses the properties of propagation of light in biaxial crystals. This new methodology allows for background suppression and will accentuate the position of a single or scattered points, features or molecules. An additional functionality of such a measurement is the capacity to retrieve the relative position of several separate features.

POTENTIAL APPLICATIONS 

• Wafer alignment and pattern overlay (semiconductor process applications)
• Automated microscopic systems
• Single molecule detecting and positioning
• Nanobiotechnology - for improved effectiveness and reliability in diagnostic applications

ADVANTAGES

• Increased resolution for position measurements of a single point, potentially higher than regular diffraction-limited optical systems.
• The measurement will be more immune to noise introduced by the detector discretization
• Capable of higher accuracy in measuring the position or velocity distribution of multiple light points
• Provides a direct and accurate measurement of the relative position of two or more features
• Simple, robust background suppression
• The field depth of the measurement is larger than a comparable lens field depth