The point-spread function of fiber-coupled area detectors.

Area of Science:

• Medical Physics
• X-ray Imaging
• Detector Technology

Background:

• Accurate characterization of the point-spread function (PSF) is crucial for quantitative analysis in X-ray imaging.
• Fiber-optic taper-coupled CCD detectors are widely used in various imaging applications.

Purpose of the Study:

• To precisely measure and model the PSF of a fiber-optic taper-coupled CCD area detector.
• To identify the dominant factors contributing to the PSF's behavior, particularly its 'tails'.

Main Methods:

• Measurement of the PSF using a 20 µm X-ray beam.
• Extensive signal averaging (~2000-fold) over five intensity decades.
• Analysis of the PSF shape, comparing it to theoretical models and geometric considerations.

Main Results:

• The PSF tails deviate significantly from Gaussian or Lorentzian profiles.
• The observed PSF shape closely matches the solid angle subtended by a pixel.
• An inverse cube law describes the PSF tails at larger distances from the beam impact point.
• The fiber-optic taper, not the phosphor, primarily dictates the PSF tail behavior.

Conclusions:

• The PSF of fiber-coupled CCD detectors is best modeled by a Moffat function.
• Understanding the PSF is essential for optimizing image quality and quantitative accuracy in X-ray detector systems.
• The findings have implications for the design and application of fiber-coupled CCD detectors in scientific and medical imaging.