Abstract: Systems and methods for digital detection of an analog tomographic signal are described. The methods include receiving an amplitude-modulated analog signal containing tomographic information, the analog signal having a modulation frequency, f?i; and converting the analog signal into a digital signal at a sampling frequency, fs, to produce a number of samples, K. The digital signal is multiplied by an in-phase reference signal to obtain an in-phase signal component, the in-phase reference signal having the frequency, f?i; and the digital signal is multiplied by a quadrature reference signal to obtain a quadrature signal component, the quadrature reference signal having the frequency, f?i. The in-phase signal component and the quadrature signal component are passed through the K-point averaging filter. A signal amplitude is computed based on the filtered in-phase signal component and the filtered quadrature signal component, the signal amplitude being representative of the tomographic information.

Abstract: Systems and methods for digital detection of an analog tomographic signal are described. The methods include receiving an amplitude-modulated analog signal containing tomographic information, the analog signal having a modulation frequency, f?i; and converting the analog signal into a digital signal at a sampling frequency, fs, to produce a number of samples, K. The digital signal is multiplied by an in-phase reference signal to obtain an in-phase signal component, the in-phase reference signal having the frequency, f?i; and the digital signal is multiplied by a quadrature reference signal to obtain a quadrature signal component, the quadrature reference signal having the frequency, f?i. The in-phase signal component and the quadrature signal component are passed through the K-point averaging filter. A signal amplitude is computed based on the filtered in-phase signal component and the filtered quadrature signal component, the signal amplitude being representative of the tomographic information.

Abstract: The present invention provides systems, methods and apparatuses that perform digital detection for use in optical tomography. Methods and systems are provided in which digital lock-in detection is performed using an algorithm that employs a phase-independent quadrature technique. Methods and systems are provided in which a unique manipulation of an ordinary averaging filter optimized for sources discrimination and the consequent sampling constraints is presented as a novel filtering scheme for the lock-in detection. Systems and apparatuses are provided which include a digital signal processor which performs digital lock-in detection and an integrated complex programmable logic device for timing control. Apparatuses are provided which include an instrument having an integrated digital signal processor for performing digital processing and detection for use in optical tomography.