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Metrology Applications using Digital Holography Microscopy (DHM®): from pioneer work to advanced applications

Surface finish measured using Digital Holography Microscopy (DHM®)

Finitura superficiale misurata mediante microscopia olografica digitale (DHM®)

Post publication date:

Thursday, June 17, 2021

From Pioneer work in 1999...

Optics Letters (Vol. 24, No. 5) and Applied Optics (Vol. 38, No. 34)

The first simultaneous reconstructions of both optical topography and intensity image out of a single hologram acquired in off-axis configuration were demonstrated by Lyncée CTO Etienne Cuche and his co-workers.

The principle of this new full field imaging method is demonstrated for

reflection microscopy
transmission microscopy
lens-less set ups

Many commercial applications are foreseen for both bio-imaging and material sciences applications.

DHM® specifications in 1999

Camera 512x512 pixels, 8 bits
Reconstruction rate ≈ 1 Hz
Vertical resolution ≈ 10 nm

... to revolutionary and matured applications in 2021

Journal of Physics: Photonics

The Journal of Physics Photonics reports cutting edge commercial metrology applications exploiting the DHM unique specificities:

Camera frame data acquisition rate: up to 100 kHz @ 1 MPixels
Real time data display: > 60 fps
Interferometric: subnanometer vertical resolution
In-situ measurements: in air, liquids, vacuum, ...

Metrology certifications

As a non-scanning technology, DHM refers purely to laser wavelengths for height measurements.
The measured height values do not depend on any scanning calibration, precise positioning, absence of long term drift, repeatability of interferometric piezo-controller, or on any motorized displacement.

3D optical profilometry

Topography measurements with interferometric resolution in the folllowing domains:

Semiconductor
Micro-optics
Micro-nano systems
Smart surfaces and polymers
Microfluidics
Watch industry

4D (Time-resolved 3D)

Acquisition at camera rate @ 194 fps standard and optionaly >100 kfps enables characterization of samples real time response due to:

Thermodynamic changes
thermal expansion, melting, evaporation …
Chemical action
electro deposition, corrosion, etching, dissolution …
Mechanical forces
material release, pressure, tribology indentation …
Light irradiance
Electromagnetic forces
...

Large surfaces measurements

Automated samples stages in conjunction with fast acquisiton rates and short acquisition time (i.e short camera shutter duration) enables:

Stitching over large areas
Full wafer inspection
Fast defects screening

In the signature recognition application shown here, the Institute of Forensic Sciences in Shanghai, China, measure surface of 20 mm x 30 mm, i.e. 3000 single images in less than 60 seconds.

Environmental & in-situ