A Stochastic Model for Electron Multiplication Charge-Coupled Devices - From Theory to Practice

Electron multiplication charge-coupled devices (EMCCD) are widely used for photon counting experiments and measurements of low intensity light sources, and are extensively employed in biological fluorescence imaging applications. These devices have a complex statistical behaviour that is often not fully considered in the analysis of EMCCD data. Robust and optimal analysis of EMCCD images requires an understanding of their noise properties, in particular to exploit fully the advantages of Bayesian and maximum-likelihood analysis techniques, whose value is increasingly recognised in biological imaging for obtaining robust quantitative measurements from challenging data. To improve our own EMCCD analysis and as an effort to aid that of the wider bioimaging community, we present, explain and discuss a detailed physical model for EMCCD noise properties, giving a likelihood function for image counts in each pixel for a given incident intensity, and we explain how to measure the parameters for this model from various calibration images. © 2013 Hirsch et al.

Nanostructuring of materials for device and sensor applications

The recent developments in nanotechnology are reviewed, with particular emphasis on its application in microsystem technology where increased reliability is achieved by integrating the sensor and the readout electronics on the same substrate. New applications may be possible using integrated micromechanical clips to connect optic fibers and components in integrated silicon systems. Some of the key developments in enabling technologies are also described, including the control of thin film deposition, nanostructuring to tailor the properties of thin film, silicon micromachining to make sensors, and microclips for the low-cost assembly of integrated optical microsystems.

Challenges in visible wavelength detection using optically transparent oxide semiconductors

We discuss the development of amorphous oxide semiconductor technology for optical sensor applications. In particular, we discuss the challenges of detecting visible wavelengths using this family of materials, which are known to be optically transparent due to their relatively large bandgap energy. One of the main issues with amorphous oxide semiconductors (AOS) is the ionization of the oxygen vacancies (VO) under illumination. While this can be beneficial in terms of optical absorption and high photoconductive gain, it can give rise to persistent photoconductivity (PPC). We will present techniques to overcome the PPC, and discuss how to achieve the high photoconductive gain for image sensor applications. © 2012 IEEE.

A resonant micromachined electrostatic charge sensor

A micromachined electrometer, based on the concept of a variable capacitor, has been designed, modeled, fabricated, and tested. The device presented in this paper functions as a modulated variable capacitor, wherein a dc charge to be measured is up-modulated and converted to an ac voltage output, thus improving the signal-to-noise ratio. The device was fabricated in a commercial standard SOI micromachining process without the need for any additional processing steps. The electrometer was tested in both air and vacuum at room temperature. In air, it has a charge-to-voltage conversion gain of 2.06 nV/e, and a measured charge noise floor of 52.4 e/rtHz. To reduce the effects of input leakage current, an electrically isolated capacitor has been introduced between the variable capacitor and input to sensor electronics. Methods to improve the sensitivity and resolution are suggested while the long-term stability of these sensors is modeled and discussed. © 2006 IEEE.

A closely integrated digital image capture device for embedded applications

A modular image capture system with close integration to CCD cameras has been developed. The aim is to produce a system capable of integrating CCD sensor, image capture and image processing into a single compact unit. This close integration provides a direct mapping between CCD pixels and digital image pixels. The system has been interfaced to a digital signal processor board for the development and control of image processing tasks. These have included characterization and enhancement of noisy images from an intensified camera and measurement to subpixel resolutions. A highly compact form of the image capture system is in an advanced stage of development. This consists of a single FPGA device and a single VRAM providing a two chip image capturing system capable of being integrated into a CCD camera. A miniature compact PC has been developed using a novel modular interconnection technique, providing a processing unit in a three dimensional format highly suited to integration into a CCD camera unit. Work is under way to interface the compact capture system to the PC using this interconnection technique, combining CCD sensor, image capture and image processing into a single compact unit. ©2005 Copyright SPIE - The International Society for Optical Engineering.