What is the OPD file format?
An .opd file is a scientific measurement data file produced by Durango Interferometry Software from Diffraction International Ltd. OPD stands for Optical Path Difference - the wavefront deviation measured by an interferometer when evaluating precision optical components such as lenses, mirrors, and prisms.
Each .opd file stores a two-dimensional phase/height map (a grid of wavefront measurements) together with metadata including instrument parameters, measurement conditions, and date. This data is used in precision optics manufacturing and quality control to quantify surface errors and lens aberrations to sub-wavelength accuracy.
Approximately 45% of .opd files use the OLE2 Compound File Binary Format (CFBF) container - identifiable by the standard OLE2 magic bytes D0 CF 11 E0 A1 B1 1A E1 at the file start. The remainder use a raw binary variant. The internal structure is tied to the Durango software release and is not independently standardized.
Durango Interferometry Software supports data acquisition from all interferometer types, as well as analysis, simulation, and import/export functions. The software is available as a free download from diffraction.com.
Note that the .opd extension is also used independently by Kofax OmniPage for saved OCR documents - a completely unrelated format with no connection to interferometry measurement data.
Security & safety
RISK: LOWScientific data file; no executable content. Safe to open with Durango software.
Format details
in a nutshell- OmniPage Document (Kofax/Nuance) - OmniPage OCR software saves scanned documents with recognized text as .opd files (OLE2-based); entirely unrelated to interferometry.
Programs that open OPD files
Windows1 app
Durango Interferometry Software
Free File → Open → select the .opd file. Displays wavefront map and measurement statistics. Technical details
deep spec| Format type | Scientific wavefront measurement data file |
| Encoding | Binary |
| Byte order | Little-endian (OLE2 convention) |
| Container | OLE2 / Compound File Binary Format (CFBF) - approximately 45% of files; remainder use raw binary |
| Magic bytes | D0 CF 11 E0 A1 B1 1A E1 (standard OLE2 header, where CFBF container is used) |
| Compression | None documented |
| Encryption | None documented |
| Typical size | Tens of KB to several MB (depends on measurement array dimensions) |
| Data payload | 2D optical path difference (OPD) phase/height map array from interferometer measurement |
| Array dimensions | Determined by interferometer CCD resolution (e.g., 640×480 or higher) |
| Metadata stored | Instrument type, measurement date, acquisition parameters, measurement conditions |
| Application domain | Precision optics testing - surface quality evaluation and lens aberration quantification |
| Associated OS | Windows |
| Extension conflict | .opd is also used by Kofax OmniPage for saved OCR documents (completely unrelated) |
| Released | ~1990s (Durango software for interferometry instrumentation) |
| Specification | www.diffraction.com |
OPD conversions
Community Q&A
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