KEYWORDS: Sensors, Cameras, Microscopy, Light emitting diodes, Photodetectors, Signal to noise ratio, Time metrology, Statistical methods, Optical testing, Single photon
In modern single pixel microscopy techniques, like Nano-Illumination Microscopy, long measurement times can become a major issue, especially when imaging biological tissues with large field of view. Usually, light intensity measurements are performed with CMOS pixels, with typical integration times around tens of milliseconds. In this work, we propose to obtain a light intensity measurement indirectly by applying statistical techniques to the photon arrival times gathered with an SPAD photodetector. We will present how the different statistical measurements can be used to minimize the total acquisition time and minimize also the hardware required. In this work, with captures of 256 SPAD measurements, reducing measurement time from 50ms to 50us. The dynamic range is extended by combining multiple statistical techniques with standard intensity measurements. This paves the way to practical Nano-Illumination Microscopy and other single pixel microscopy techniques.
This work presents a compact low-cost and straightforward shadow imaging microscopy technique based on spatially resolved nano-illumination instead of spatially resolved detection. Independently addressable nano-LEDs on a regular 2D array provide the resolution of the microscope by illuminating the sample in contact with the LED array and creating a shadow image in a photodetector located on the opposite side. The microscope prototype presented here is composed by a GaN chip with an 8x8 array of 5μm-LEDs with 10 μm pitch light sources and a commercial CMOS image sensor with integrated lens used as a light collector. We describe the microscope prototype and analyze the effect of the sensing area size on image reconstruction.
This work presents a first prototype for a new approach to microscopy: a system basing its resolving power on the light emitters instead of the sensors, without using lenses. This new approach builds on the possibility of making LEDs smaller than current technology sensors, offering a new approach to microscopy we plan on developing towards superresolution. The microscope consists on a SPAD based camera, a 8x8 LED array with 5x5 μm LEDs distributed with a pitch of 10 μm, and discrete driving electronics to control them. We present simulations of the system, as well as the first microscope prototype implementing the method, and the results obtained through it.
KEYWORDS: Sensors, Single photon, Avalanche photodiodes, CMOS technology, Electronics, Avalanche photodetectors, Signal to noise ratio, Electron beams, Diodes, TCAD
Advances in SPAD arrays propose improving the fill factor by confining several SPADs in the same well, with a main issue related to crosstalk. For measurements triggered only in well-defined time periods that can be known in advance, the pixels can be inhibited before the arrival of the crosstalk charge. This paper reports the crosstalk characterization of in an array of SPADs fabricated in a conventional CMOS technology in the same n-well (fill factor 67%). A long gating time gives a crosstalk not less than 2.75%, while reducing it below 2.5 ns completely eliminates crosstalk, as predicted by the theory and by TCAD simulations.
It is described the architecture of the electronics for the control of a wireless endoscopic capsule with locomotive capabilities and advanced sensing and actuating functions. Special emphasis is done to the description of the driver used for locomotion, which is the most innovative element in the capsule.
KEYWORDS: System on a chip, Virtual colonoscopy, Solar cells, Telecommunications, Computer programming, Prototyping, Sensors, Clocks, Control systems, Optical communications
This paper presents a System On Chip (SoC) designed specifically to control a mm3- sized microrobot called I-SWARM. The robot is intended to be part of a colony of 1000 I-SWARM robots for studying swarm behavior in real time and in a real swarm. The SoC offers a well-suited hardware platform to run multi-agent systems software. It is composed of an 8051 microcontroller with 2 kB of data memory and 8 kB of program memory. The processor is provided with specific hardware modules for controlling the locomotion unit, the communications and the vibrating contact sensor of the robot. These modules perform basic tasks as movements or communications so the 8051 can focus on processing data and taking decisions. With these capabilities, the robot is able to avoiding collisions with other members of the swarm, performing cooperative tasks, sharing information and executing specialized tasks. The SoC has been fabricated with a 0.13 &mgr;m ultra low power CMOS process of STMicroelectronics and consumes less than 1 mW.
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