Park Systems’ reflection-configured Digital Holographic Microscope (DHM®) is a non-contact scanning technique ideally suited to the characterization of vibration and both static and dynamic three-dimensional topography.
DHM-R measuring through a glass window. Image Credit: Park Systems
Unparalleled Speed
Rapid 3D Profilometry
DHM® can measure a surface's 3D topographical map in a single acquisition, without a scanning mechanism. Its camera rate of up to 100,000 frames per second provides rapid acquisition, enabling:
- Routine inspections with high productivity
- 3D analysis of the dynamic behavior of deformable samples
- Rapid screen and large surface analysis
- 3D topography capture on production lines with no need to halt the sample
MEMS Analysis at up to 25 MHz
An optional stroboscopic unit can synchronize DHM® measurements with a MEMS device’s excitation signal. This approach to data collection and analysis can be used to generate:
- Vibration amplitude with a resolution of five pm for out-of-plane and one nm for in-plane displacements
- Characterization of complex sample geometries and motions, including samples with holes
- Frequency resonances and responses
- Time sequence of 3D topographies
Innovation
Measurement in Controlled Environmental Conditions
The unique optical design of DHM® ensures high-quality measurements:
- In environmental and vacuum chambers with regulated temperature, humidity, pressure, and gas composition
- Through immersion liquids and glass
Measurement of the Topography of Transparent Patterns
The optional DHM® Reflectometry analysis software also enables measurement of:
- Transparent structures’ topography
- Topography of liquids and soft materials
- The refractive index values and thicknesses of structured multi-layers with thicknesses from 10 nanometers to tens of microns
Time sequence of 3D topographies, limited by camera rate: evaporation of a liquid drop. Image Credit: Park Systems
Digital Holographic Microscopy (DHM®) Technology
Reflection DHM. Image Credit: Park Systems
Patented Digital Holographic Microscopy (DHM®) technology uses a digital camera to capture holograms resulting from interference between an internal reference beam and the sample's reflected beam. These holograms are then numerically processed to generate a three-dimensional optical map of the sample under investigation.
The vertical calibration of DHM® is defined by laser wavelength. It provides reproducible data and high accuracy, measuring with interferometric resolution, such as a subanometric vertical resolution, and a lateral resolution limited by the choice of microscope objective.
Advanced numerical processing of the recorded hologram enables crisp focus, either concurrently or as a post-processing step following measurement, which is possible without manually altering the height of the sample.
Reflection DHM® is available in three different versions, based on the number of wavelengths available:
- R1000 models use a single wavelength, making them well-suited to measuring smooth surfaces and vibrations.
- R2100 models can measure two wavelengths concurrently, making them well-suited for measuring complex or discontinuous structures.
- R2100 models are R2100 models that leverage a third source to increase measurement capabilities, making them particularly suited to measuring transparent patterns.
Technical Specifications
Source: Park Systems
| System |
| DHM models |
R1000 |
R2100 |
R2200 |
| Number of laser sources |
1 |
2 |
3 |
Operating wavelength
(± 1.0 nm) |
675 nm |
675 nm,
794 nm |
666 nm, 794 nm,
675 nm |
| Laser wavelength stability |
0.01 nm / °C at 675 nm |
| Sample stage |
Manual or motorized XYZ stages up to 300 mm x 300 mm x 38 mm travel range |
| Objectives |
Magnification 1.25x to 100x, standard, high NA, long working distance, water/oil immersion |
| Objective turret |
6 positions |
| Computer |
Workstation with the latest multicore Intel® processor, high-performance graphics card optimized and configured for DHM, with a screen of at least 21 inches, and a mouse |
| Software |
Proprietary Koala software based on C++ and .NET
Additional optional software modules are available for advanced analysis |
| Data compatibility |
Measurement data recorded in bin format, exportable in .txt format, recorded and reconstructed images exportable in .tif format or .txt array |
| Performance |
| Measurement mode |
Single wavelength
at 675 nm |
Short synthetic
wavelength at 4.4 μm |
Long synthetic
wavelength at 50 μm |
| DHM models |
R1000, R2100, R2200 |
R2100, R2200 |
R2200 |
| Accuracy 1 [nm] |
0.15 |
0.15 / 3.0* |
20 |
| Vertical resolution 2 [nm] |
0.30 |
0.30 / 6.0* |
40 |
| Repeatability 3 [nm] |
0.01 |
0.01 / 0.1* |
0.5 |
| Vertical measuring range |
up to 200 μm |
up to 200 μm |
up to 200 μm |
| Max. height of steps with sharp edges |
up to 333 nm4 |
up to 2.1 μm4 |
up to 24 μm4 |
| Surface type |
Smooth surfaces |
Complex or
discontinuous
structures |
Complex or
discontinuous
structures |
| Vertical calibration |
Determined by an interferometric optical filter, ±0.1 nm |
| Acquisition time |
Standard: 500 μs (optional 10 μs) |
| Acquisition rate |
Standard: 190 fps (1024 x 1024 pixels). (optional up to 100,000 fps). |
| Reconstruction rate |
Up to 25 fps 1024 x 1024 pixels hologram (data analysis dependent) (optional up to 60 fps) |
| Lateral resolution |
Objective dependent, down to 300 nm** |
| Field of view |
Objective dependent, from 66 μm x 66 μm up to 5 mm x 5 mm** |
| Working distance |
Objective dependent, from 0.3 to 18 mm** |
| Digital focusing range |
Up to 50x depth of field (objective dependent) |
| Min. sample reflectivity |
Less than 1 % |
| Sample illumination |
Down to 1 μW/cm2 |
| Stroboscopic unit |
Compatibility with single and short synthetic wavelengths |
| Power requirements |
| Input voltage |
85-260 VAC – 50/60 Hz |
| Power requirements |
max. 250 W |
| Dimensions & weight |
| Dimensions (L x W x H) |
600 x 600 x 800 mm |
| Weight |
48 kg |
1 As demonstrated by taking the temporal standard deviation on 1 pixel over 30 measurements
2 Defined as twice the accuracy
3 As demonstrated by taking the one sigma Rq value of 30 repeatability measurements without sample
4 Depends on the laser source(s) and operating wavelength(s)
* With / Without single wavelength mapping
** Objectives specifications on www.lynceetec.com/microscope-objectives
Reflection DHM® mounted on a vacuum chamber. Image Credit: Park Systems
A range of different solutions is compatible with DHM® systems. These include:
- Objectives with cover-glass correction, extra LWD, for immersion, etc.
- Remote DHM control and automation via a remote TCP/IP module
- An optional stroboscopic unit suitable for the investigation of MEMS
- A motorized stage for stitching and automation
- Environmental chamber for measuring under controlled conditions