Super resolution exploits quantum states of light to overcome the major limitations of microscopy based on classic light (diffraction limit). In this field, Istituto Nazionale di Ricerca Metrologica (INRiM) demonstrated the results obtainable in terms of resolution in confocal microscopy, succeeding in discriminating the position of diamond colour centres located at a distance lower than the diffraction limit. These results have been obtained exploiting super-resolved maps based on the measurements of high order autocorrelation functions. This thesis work aims at developing a SPAD imager able to optimize these measurements. It is implemented in 0.16 μm BCD technology which allows to integrate on the same die high efficiency sensors that can be operated at room temperature along with processing electronics. The main feature of this imager composed by 96 × 96 SPAD pixels is represented by its ability of storing the triggering time instant of each detector in order to identify multiple pixel coincidences by post processing, even between detectors at a far distance. It also allows to externally select the time duration of the coincidence window. The advantages of this chip are also represented by the optimization of the readout operation, both in terms of time duration and amount of data transmitted externally. In fact, this imager is characterized by a global logic able to skip all the rows in which none of the detectors absorbed photons. In this way, considering the very low photon flux which characterize the target application, the reading time is widely reduced and it can reach, in case of just one processed row, 710 ns using a 100 MHz readout clock, while reading the entire array would imply 12 µs. Moreover, a multi-gate approach is used, which avoids stopping the array during the readout time, enabling multiple data acquisitions.
La super risoluzione sfrutta luce quantistica in modo da oltrepassare le limitazioni della microscopia basata su luce classica (limite di diffrazione). In questo contesto l’Istituto Nazionale di Ricerca Metrologica (INRiM) ha dimostrato i risultati ottenibili in termini di risoluzione in microscopia confocale, riuscendo a discriminare la posizione di centri colorati in diamanti situati ad una distanza minore del limite di diffrazione. Tali risultati sono stati ottenuti utilizzando mappe a super risoluzione basate sulla misurazione di ordini elevati della funzione di autocorrelazione. Questo lavoro di tesi consiste nel progettare un rivelatore SPAD in grado di ottimizzare queste misure. Per la sua implementazione è stata scelta la tecnologia BCD 0.16 μm, la quale permette di integrare sullo stesso substrato sensori ad alta efficienza utilizzabili a temperatura ambiente ed elettronica di elaborazione. La caratteristica principale di questo rilevatore composto da 96 × 96 SPAD pixels, consiste nell’abilità di memorizzare l’istante di scatto di ciascuno SPAD in modo da individuare in post processing molteplici tipi di coincidenze tra pixels, anche distanti tra loro. È inoltre permesso regolare la durata della finestra di coincidenza esternamente. I vantaggi di questo chip risiedono anche nell’ottimizzazione della fase di lettura, non solo in termini di tempo ma anche di quantità di dati trasmessi all’esterno. Infatti, esso è caratterizzato da una logica globale in grado di saltare la lettura di intere righe nelle quali nessun sensore abbia rilevato un fotone. In questo modo il tempo di lettura è di gran lunga ridotto, fino a raggiungere, nel caso in cui solo una riga vada processata, appena 710 ns con un clock di lettura di 100 MHz, mentre leggere l’intero rivelatore richiederebbe 12 μs. Inoltre, viene utilizzato un approccio a gate multipli, il quale permette di sfruttare in modo efficiente il tempo in cui la matrice viene letta per registrare nuove acquisizioni di dati.
Multi-photon coincidence-detection SPAD imager for super resolution microscopy
PERINELLI, SOFIA
2019/2020
Abstract
Super resolution exploits quantum states of light to overcome the major limitations of microscopy based on classic light (diffraction limit). In this field, Istituto Nazionale di Ricerca Metrologica (INRiM) demonstrated the results obtainable in terms of resolution in confocal microscopy, succeeding in discriminating the position of diamond colour centres located at a distance lower than the diffraction limit. These results have been obtained exploiting super-resolved maps based on the measurements of high order autocorrelation functions. This thesis work aims at developing a SPAD imager able to optimize these measurements. It is implemented in 0.16 μm BCD technology which allows to integrate on the same die high efficiency sensors that can be operated at room temperature along with processing electronics. The main feature of this imager composed by 96 × 96 SPAD pixels is represented by its ability of storing the triggering time instant of each detector in order to identify multiple pixel coincidences by post processing, even between detectors at a far distance. It also allows to externally select the time duration of the coincidence window. The advantages of this chip are also represented by the optimization of the readout operation, both in terms of time duration and amount of data transmitted externally. In fact, this imager is characterized by a global logic able to skip all the rows in which none of the detectors absorbed photons. In this way, considering the very low photon flux which characterize the target application, the reading time is widely reduced and it can reach, in case of just one processed row, 710 ns using a 100 MHz readout clock, while reading the entire array would imply 12 µs. Moreover, a multi-gate approach is used, which avoids stopping the array during the readout time, enabling multiple data acquisitions.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/169474