Minimizing read noise in liquid crystal x-ray detectors using particle-in-binder HgI2 layers.

Abstract

A liquid crystal x-ray detector was manufactured by coating HgI2 on a thin glass substrate liquid crystal cell in guest-host (GH) mode. The HgI2 layer was produced using the particle-in-binder (PIB) method. A reflective optical system was constructed so that one pixel corresponds to a 45 × 45 µm2 area of the liquid crystal cell. A quantification process was established to convert liquid crystal images into x-ray images. As a result, the signal-to-noise ratio (SNR) was 50 when irradiated with 32 keV, 10 mR/cm2 x rays. In the liquid crystal x-ray detector, read noise decreases as the intensity of the light source increases. The full well capacity (FWC) of the image sensor was 100 ke, measured in the range of 25 ke to 70 ke, with a read noise of ∼1%. To achieve an SNR at the shot noise level, an FWC of 500 ke is required, with measurements taken in the 100-400 ke range. In this case, the read noise is less than 0.3%, and the measurement precision approaches the physical limit.