PicoQuant - It's about time

Photon Counting Detectors

τ-SPAD

Single Photon Counting Module

  • Timing resolution down to <350 ps (FWHM)
  • Detection efficiency up to 70%
  • Very low dark counts
  • Active area 150 µm
  • NIM and TTL signal output
  • Optional fiber connector
  • Optional FAST model with timing down to 150 ps (FWHM)

This product is discontinued as of December 2014.

Please check our other single photon sensitive detectors for possible alternatives.


The τ-SPAD photon counting modules combines Laser Components' ultra-low noise VLoK silicon avalanche photodiode with specially developed quenching electronics from PicoQuant (covered by patent DE 10 2010 060 527). The low dark counts and high photon detection efficiency make it an ideal detector for single molecule applications, like Fluorescence Correlation Spectroscopy (FCS) or Fluorescence Lifetime Imaging (FLIM).

Detection efficiency up to 70%

Detection efficiency of the Tau-SPADThe τ-SPAD features an extremely high photon detection efficiency of typically 70 % at 670 nm and can be used to detect single photons over the 400 nm to 1100 nm wavelength range. It can be supplied with an easy to use FC/PC connection for optical fibers or as a free-beam module.

Timing resolution down to 350 ps

The τ-SPAD generates a NIM and a TTL output pulse per detected photon and can therefore be directly interfaced with different data acquisition systems such as TCSPC electronics. The photon timing response can be as short as 350 ps (FWHM, depending on module, wavelength and signal rate).

τ-SPAD FAST for timing down to 150 ps

An alternative version of the τ-SPAD (τ-SPAD FAST) features a timing resolution between 150 ps and 400 ps (FWHM, depending on conditons and module). These modules are based on a different APD that has a dark counte rate <500 cps and a detection efficiency up to 70% at 470 nm. Please contact us for further details.


  τ-SPAD τ-SPAD FAST
Spectral range 400 nm - 1100 nm 400 nm - 1100 nm
Active area diameter 150 µm 500 µm
Photon timing resolution* 350 ps - 800 ps (FWHM, depending on module, wavelength and signal rate) 150 ps - 400 ps (FWHM, depending on module, wavelength and signal rate)
Afterpulsing probability (0 to 500 ns)* < 1 % (typical) < 5 % (typical)
Dead time < 70 ns (typical) < 70 ns (typical)
Fiber connector type (optional) FC/PC FC/PC
Dark count rate
τ-SPAD-20 < 20 cps (available upon request) <500 cps (typical)
τ-SPAD-50 < 50 cps (available upon request)
τ-SPAD-100 < 100 cps (available upon request)
τ-SPAD-250 < 250 cps (available upon request)
Photon detection efficiency* (typical values, without fiber connector)
@ 405 nm 10 ± 5 % 50 ± 5 %
@ 470 nm 30 ± 5 % 70 ± 5 %
@ 670 nm 70 ± 5 % 65 ± 5 %
@ 890 nm 35 ± 5 % 20 ± 5 %
Losses due to fiber connector: approx. 10% absolute
Input / Output
NIM output
Pulse width 15 ns - 25 ns
Pulse amplitude -0.8 V to -1 V (into 50 Ohms)
Connector type SMA
TTL output
Pulse width 15 ns - 25 ns
Pulse amplitude > 2.4 V (into 50 Ohms)
Connector type Lemo, type EPS.00.250
Gating input
Input voltage TTL control, TTL high (>2.4 V) enables counting
Response time disable: < 40 ns (typ. 20 ns); enable: < 100 ns (typ. 85 ns)
Connector type SMA
Operating conditions
Supply voltage 12 V
Supply current 1.5 A (at turn on), 0.3 A (at 1 Mcps)
Operating temperature 10 °C - 40 °C

* measured by illuminating < 30 µm in the center of the active area

Typical detection efficiency vs. wavelength (without fiber connector)

Detection efficiency of the Tau-SPAD


All Information given here is reliable to our best knowledge. However, no responsibility is assumed for possible inaccuracies or omissions. Specifications and external appearances are subject to change without notice.

The following documents are available for download:



Latest 10 publications referencing SPADs

The following list is an extract of 10 recent publications from our bibliography that either bear reference or are releated to this product in some way. Do you miss your publication? If yes, we will be happy to include it in our bibliography. Please send an e-mail to info@picoquant.com containing the appropriate citation. Thank you very much in advance for your kind co-operation.