Streamlined MCRQ receiver.
The Modulo Uno is a laser interferometer featuring a streamlined version of our rugged Multi-Channel Random Quadrature (MCRQ) optical design. Unlike its larger counterpart, the Quartet, which uses two detector arrays to independently register vertically and horizontally polarized components, the Modulo Uno utilizes a single detector. However, it offers more than just a smaller size compared to the Quartet. Its innovative optical design eliminates the need to split the probe beam for processing, allowing the Modulo Uno to operate efficiently with a lower-powered laser. This not only reduces construction costs but also enables testing on sensitive materials like composites (without a beam chopper), making it particularly well-suited for biomedical applications.
FEATURES.
Robust & Versatile
The Modulo does not require high accuracy optical components or positioning, making it exceptionally rugged.
Fiberized Optical Head
A versatile fiberized optical head is easily mounted to fit a variety of measurement conditions and can be set-up for a wide-range of stand-off distances.
Analog & Digital Outputs
The Modulo produces both an analog and digital signal proportional to surface displacement.
High Sensitivity on all Surface Types and Materials
A detector array together with high transmission optics result in high sensitivity. The Modulo produces a stable, demodulated signal even when processing a highly speckled beam. Measurements can be performed on any kind of surface, including rough, porous, rusted and mirror-like.
Rapid Inspection
Efficient electronic processing allows for measurement speeds up to meters per second.
Not Wavelength Dependent
The Modulo can be fitted with a range of internal laser wavelengths ranging from visible to infrared.
Upgrades and Add-ons
Motorized Optical Head
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TECHNICAL SPECIFICATIONS.
TECHNOLOGY
Multi Channel Random Quadrature
DETECTION
Out-of-plane
CONFIGURATION
Optical FIber
INTERNAL LASER POWER
30 – 100 mW
DETECTION BANDWITH
Up to 20MHz
DIMENSIONS (L*W*H)
400*170*165 mm
WEIGHT
6.5Kg
ELECTRICAL REQUIREMENTS
110V/50Hz – 220V/60Hz
TECHNOLOGY.
The idea behind Multi-Channel Random Quadrature was to develop a laser-ultrasound technology with a robust, compact design and a large depth-of-field capable of functioning effectively in a wide range of environments without loses in sensitivity, including on rough surfaces. With support from the National Science Foundation and NASA, we developed a novel interferometric design. By collecting and processing a multitude of speckles, the Modulo is fully functional in environments which would otherwise be unsuitable for most other laser ultrasound instruments.
More about MCRQ (Multi Channel Random Quadrature)
Rational
The idea behind Multi-Channel Random Quadrature was to devise a laser-ultrasound technology with a robust, compact design and a large depth-of-field capable of functioning effectively in a wide range of environments without loses in sensitivity, including on rough surfaces. With support from the National Science Foundation and NASA, we developed the Quartet. By collecting and processing a multitude of speckles, the Quartet is fully functional in environments which would otherwise be unsuitable for most other receivers and can perform measurements on all surface types — from mirror-like to rough surfaces.
Multi Channel
Two detector arrays of 25 elements each allow the Quartet to collect more speckles than a standard receiver, which in turn translates to high sensitivity. To put it another way, employing MCQR technology is equivalent to using 50 Michelson interferometers in parallel.
The Quartet does not need to be stabilized as it relies on the random nature of speckles. Statistically, the speckle phase has a uniform distribution, meaning that it is 50% in-quadrature and 50% out-of-quadrature. The out-of-quadrature components don’t contribute to the signal, which is why we use 25 photodiodes on two detectors. Demodulation is required for both the in-phase and out-of-phase signals.
Optical Design
A laser beam generated by the internal laser passes through multiple optics within the receiver before being focused into a multimode fiber. At the end of the fiber, around 4-5% of the light is reflected back towards the receiver due to a natural optical phenomenon while the rest is focused onto the sample. The diffuse light reflected by the sample surface is collected by a large lens located at the front of the optical head, maximizing the quantity of speckles gathered for signal processing. The speckled beam then travels back through the optical fiber, interfering with the 4-5% partial reflection previously mentioned. It is important to note that the light polarization components are scrambled while traveling back through the multimode fiber. Once back in the system, the beam travels through a first Polarized Beam Splitter (PBS) which isolates the vertical polarization component and is in turn directed towards one of the two detector arrays. The rest of the beam travels through an Optical Isolator, which consists of a Faraday rotator and a PBS. This second PBS then sends the vertical (previously horizontal) component of the returning signal-beam back towards the second Multi-Channel Detector. Every signal from the photodiodes will be processed in parallel by an electronic demodulation.
Rectified Demodulation
Because of the random nature of the phase of each of the 50 signals detected, the quartet is designed to perform signal rectification without consideration of phase. The streamlined electronic processing allows the Quartet to perform single shot measurements on fast-moving objects. Rectified Demodulation is also effective at rejection of background noise vibration.
Rectified Demodulation alone has a few downsides: it has a high-frequency and small-displacement limitation, and the direction of displacement is unknown. Therefore, the Quartet also uses Linear Demodulation.
Linear Demodulation
Linear Demodulation is a similarly compact multi-channel architecture, but with a demodulation scheme that yields an output signal proportional to the wave-displacement. It is composed of a transimpedance followed by a logic control which detects the signal phase and switches between two summing amplifiers: one receives the in-phase and the other the out-of-phase signals. Lastly, both phases of the signal pass through a differential amplifier.
PATENTS.
Patent US7978341
Multi-channel laser interferometric method and apparatus for detection of ultrasonic motion from a surface.
APPLICATIONS.
Our systems have a multitude of potential applications. Listed below are a just few brief descriptions of feasibility studies done using our receivers. If you have any questions regarding applications, we would be happy to lend our expertise to your problematic.
Transducer Characterization Showing non-uniform Surface Displacement
Visible non-uniform surface displacement
- Direct Laser Ultrasonic Measurement
- 5MHz Piezo with Pulse excitation (50Vpp).
- ≈ 4nm peak-to-peak surface displacement.
- Modulo Uno with 30mW laser output with a wavelength of 1064 nm.
- NESD* on Piezo: ~ 5∙10-5nm/Hz1/2.
Animal Tissue Scan
Visible non-uniform surface displacement
- Direct Laser Ultrasonic Measurement
- 5MHz Piezo with Pulse excitation (50Vpp).
- ≈ 4nm peak-to-peak surface displacement.
- Modulo Uno with 30mW laser output with a wavelength of 1064 nm.
- NESD* on Piezo: ~ 5∙10-5nm/Hz1/2.
Noise Equivalent Surface Displacement (NESD) measurement on Chicken Breast Meat
- Stand-off distance =100mm
- Signal strength (Free mode) = 120mV/nm
- Calibration (Auto mode) = 100mV/nm
- Detection Bandwidth = 14MHz
- RMS Noise = 23mV
- NESD = 62∙10-6nm/Hz1/2
