sdtfile 2026.6.29

Read Becker & Hickl SDT files

Sdtfile is a Python library to read SDT files produced by Becker & Hickl SPCM software. SDT files contain time correlated single photon counting instrumentation parameters and measurement data. Currently only the “Setup & Data”, “DLL Data”, and “FCS Data” formats are supported.

Becker & Hickl GmbH is a manufacturer of equipment for photon counting.

Author:

Christoph Gohlke

License:

BSD-3-Clause

Version:

2026.6.29

DOI:

10.5281/zenodo.10125608

Quickstart

Install the sdtfile package and all dependencies from the Python Package Index:

python -m pip install -U sdtfile

See Examples for using the programming interface.

Source code and support are available on GitHub.

Requirements

This revision was tested with the following requirements and dependencies (other versions may work):

• CPython 3.12.10, 3.13.14, 3.14.6, 3.15.0b3 64-bit

• Numpy 2.5.0

Revisions

2026.6.29

• Fix reading SDT files with truncated embedded ZIP files (#8).

2026.6.6

• Fix potential file handle leak in SdtFile init.

• Add options for memory-mapping and locked reading to BinaryFile.

• Add option to memory-map SDT files.

• Drop support for Python 3.11 and numpy 2.0 (SPEC0).

• Support Python 3.15.

2026.2.8

• Derive SdtFile from BinaryFile (breaking).

• Rename MEASURE_INFO.MeasHISTInfo to HISTInfo to match C struct (breaking).

• Revise shaping of FCS_BLOCK data (breaking).

• Fix code review issues.

2026.1.14

• Improve code quality.

2025.12.12

• Add new SPC modules and MEASURE_INFO_EXT fields.

• Drop support for Python 3.10.

2025.5.10

• …

Refer to the CHANGES file for older revisions.

References

1. W Becker. The bh TCSPC Handbook. 9th Edition. Becker & Hickl GmbH 2021. pp 879.

2. SPC_data_file_structure.h header file. Part of the Becker & Hickl SPCM software installation.

Examples

Read image and metadata from a “SPC Setup & Data File”:

>>> sdt = SdtFile('image.sdt')
>>> int(sdt.header.revision)
588
>>> sdt.info.id[1:-1]
'SPC Setup & Data File'
>>> int(sdt.measure_info[0].scan_x)
128
>>> len(sdt.data)
1
>>> sdt.data[0].shape
(128, 128, 256)
>>> sdt.times[0].shape
(256,)
>>> sdt.close()

Read data and metadata from a “SPC Setup & Data File” with multiple data sets:

>>> sdt = SdtFile('fluorescein.sdt')
>>> len(sdt.data)
4
>>> sdt.data[3].shape
(1, 1024)
>>> sdt.times[3].shape
(1024,)
>>> int(sdt.setup.bh_bin_hdr['soft_rev'])
850
>>> sdt.close()

Read image data from a “SPC FCS Data File” as numpy array:

>>> sdt = SdtFile('fcs.sdt')
>>> sdt.info.id[1:-1]
'SPC FCS Data File'
>>> len(sdt.data)
1
>>> sdt.data[0].shape
(512, 512, 256)
>>> sdt.times[0].shape
(256,)
>>> sdt.close()