Simulation modelling for the analysis and the optimal design of - - PowerPoint PPT Presentation

Simulation modelling for the analysis and the optimal design of SPAD detectors for time-resolved fluorescence measurements

Marina Repich, David Stoppa, Lucio Pancheri, Gian-Franco Dalla Betta

Typical fluorescence measurement setup

The photodetector

determines the accuracy

• f the measurements.

General performance of

measurement setup are defined by all part: from light source to software.

Fluorescent sample Light source Excitation light Optical system Emitted light Photo detector Data processing

System structure

The simulation model

consists of a set of independent blocks each of them simulates an appropriate part of the experiment

Optimization algorithm

provide an opportunity to fit SPAD and experimental setup parameters to achieve the optimal system performance

• !
• !
• "
• "

Simulation workflow

Time in nanoseconds

• #
• $#%
• $
• &
• '

'## (% # )

• $#

#

• #

% )&

&

Simulation workflow

Time in nanoseconds Power in con. un.

• #
• $#%
• $
• &
• '

'## (% # )

• $#

#

• #

% )&

&

• Light pulse

28.5 29 29.5 30 30.5 Time in ns Power FWHM

Light spectrum

Wavelenght in nm Power

*+

Simulation workflow

Time in nanoseconds Power in con. un.

• #
• $#%
• $
• &
• '

'## (% # )

• $#

#

• #

% )&

&

• )

ln ( * z t t τ − + =

• Assumptions:
• the light absorption
• beys the Beer-

Lambert law;

• fluorophores have

uniform distribution;

• the optical density of

the fluorescent sample is negligible;

• fluorescence decay

is monoexponential;

• there are no other

processes influencing light emission except fluorescence.

540 590 640 Wavelength in nm Power

*

Simulation workflow

Time in nanoseconds Power in con. un.

• #
• $#%
• $
• &
• '

'## (% # )

• $#

#

• #

% )&

&

• Fluorescence spectrum

540 590 640 Wavelength in nm Power Filter transfer function 0.2 0.4 0.6 0.8 1 540 560 580 600 620 640 Wavelength Probability

540 560 580 600 620 640 Wavelength in nm Power

Simulation workflow

Time in nanoseconds Power in con. un.

• #
• $#%
• $
• &
• '

'## (% # )

• $#

#

• #

% )&

&

• Time response

1 10 100 1000 10000 100000 1 1.5 2 2.5 3 3.5 4 Time in ns Event counts

Afterpulsing probability density

1000 10000 100000 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Time in ns

Photon detection probability

5 10 15 20 25 30 35 350 450 550 650 750 850 950 1050 Wavelength in nm P ro b a b ility

Dead time

4kHz

DCR

Time in nanoseconds Power in con. un.

• #
• $#%
• $
• &
• '

'## (% # )

• $#

#

• #

% )&

&

• 1

10 100 1000 10000 100000 10 20 30 40 50 Time in ns Power in con. un.

Simulation workflow

0.0001 0.001 0.01 0.1 10 20 30 40 50 Time in nanoseconds Power in con. un

• Simulation results

#,-.'/- #,-.'01

The practical and simulated

laser pulses (Picoquant LDH-P-C-470 pulsed diode laser with 80-ps FWHM)

Fluorescence decay simulated

and measured with SPAD (time-gated technique with 10ns observation window and 60ps shift)

28.5 29 29.5 30 30.5 Time in ns Counts

Future work

Further improvement of SPAD simulation

Geometry Effects related to passive quenching Temperature dependence

Including additional setup characteristics

Light source intensity Optical lenses

Implementation of optimization algorithm