AIRSCOPE

Airsocope , was developed from DASEL and is used for non-destructive testing and inspection of materials and structures, and they work by using air as the coupling medium between the transducer and the object being inspected. Airscope may be configured to operate on 2 and 32 channels.

AirScope is a non-contact ultrasound inspection system that uses air as couplant between the transducer and the component under test. This feature eliminates the problems associated with water immersion and water jet:

• Water can flow into the component structure, especially in CFRP, laminates and mask the presence of some flaws like delaminations.
• Components inspected by water coupling usually have to be dry and cleaned afterwards, increasing production time.
• There are some components that cannot be wet:
  • Some honeycomb structures
  • Aerospace components
  • Hydrophilic materials like non-cured composites.

AirScope technology was specifically designed to deal with ultrasound air-borne challenges:

• The huge impedance mismatch between air and any solid material introduces large insertion losses, which usually generate signals with poor SNR. Airscope transducers and electronics have been designed to maximize emission efficiency and reception sensitivity, providing the best possible SNR in most challenging scenarios.
• Pulse-echo inspection is virtually impossible because the large reflection coefficient (99.6%) generates a large interface echo that mast any defect inside the component. That is the reason why non-contact inspections are performed in through-transmission mode from both sides of the component.
• On the other hand, the large velocity mismatch between air and solids generates strong refraction, and the critical angle for longitudinal waves is rather low (about 6º for CFRP) making alignment between transducers critical. High precision of AirScope mechanics warranties a total control of incidence angle, minimizing signal loss due to transducer misalignment.
• Increasing frequency increases attenuation in air. Although it is possible to manufacture transducer with -20dB sensitivity at 250 kHz, it is quite difficult to achieve  -40 dB sensitivity at 1 MHz. Airscope transducers manufacturing technique allows focusing the beam at the component surface, maximizing the transmitted energy, sensitivity and resolution.
• Different from CFRP monolithic components, honeycomb structures must usually be sealed when inspected by water coupling, to avoid water to flow into the part. Airscope system allows inspecting this kind of parts without contact, maintaining the core integrity without sealing the component edges. Defects that can be detected include: delaminations, inclusions, crushed core, lack of adhesive, unbound, etc.

The small size of the AirScope system allows mounting it directly on the UT inspection head, reducing noise from long cables. Alternatively, low noise pre-amplifiers can be provided to be placed near the transducers, while the control and acquisition unit is located in a remote site.

The AirScope is the only non-contact multi-channel ultrasound inspection system. Depending on the number of the channels, it is possible to multiply up to 8 the inspection speed.

1. Channels

The AirScope system has 2/4 physical multiplexed channels for emission (connectors) and 2/4 physical multiplexed channels for reception (connectors). The user can program an acquisition sequence with up to 32 virtual channels, these virtual channels are defined assigning one connector for emission of the pulse and other connector for reception of the signal, and it is possible to share connectors between virtual channels.

The acquisition parameters are independent for each virtual channel (emitter connector, receiver connector, pulser parameters, average, filters, range, etc.)

Channels
Emitter channels:	(AirScope MX 2CH) 2 channels (AirScope MX 4CH) 4 channels	(1)
Receiver channels:	(AirScope MX 2CH) 2 channels (AirScope MX 4CH) 4 channels	(1)

Pulser	Negative square wave pulse
Excitation voltage	Programmable -20 V to -400 V
Pulse width	Programmable from 25 ns to 25 μs, with resolution of 10 ns
Burst mode	Up to 256 consecutive pulses

Trigger Modes
Software Trigger
Internal PRF
Encoder Trigger
External Input Signal Trigger

Control Connectors	Description
“ENC A”, “ENC B”	2 quadrature encoder inputs and 5 VDC power supply (TTL non-optocoupled and non-differential inputs with 2K7 pull-up resistor)	(1)
“Trig”	External trigger input. (Optocoupled) Amplitude input range à 3.5 V to 10 V Pulse width minimum à 200 ns	(2)
“Sync”	Sync output Amplitude pulse à 3,3 V	(3)
“Expansion Port-1” “Expansion Port-2”	Expansion ports to increase the functionality of the AirScope connecting others IO modules	(4)
“Gate”	(Optional) Alarm output signal, this output generates a pulse when any gate detects a signal peak	(4)
“A-Scan”	(Optional) Analog output of the A-Scan signal	(4)
“Serial Port Monitor”	Serial port output to check maintenance operations
IP Select “Def”, “User”	This control allow to select the AirScope network settings: Def: Default network settings: IP address: 192.168.2.10 TCP Port: 5001 UDP Port: 6008 User: Network settings that the user can change using the UT-View application.

Amplifier	Wide-band and low-noise amplifier
Gain	Programmable from  0 dB to 100 dB Time-Gain-Compensation function (TGC)
Bandwidth (@-6 dB)	50 KHz to 4.7 MHz

Acquisition Modes:	(AirScope MX 2CH) Transmission, with 2 emitter channels, and 2 receiver channels. (AirScope MX 4CH) Transmission, with 4 emitter channels, and 4 receiver channels.
	Automatic start of the acquisition with programmable threshold (echo-start)
Acquisition depth	1. In VIDEO acquisition mode, EMI Filter or Average: 16.384 samples with any sampling frequency. (Air distance: 557 mm @ Sampling Frequency 10 MHz) 2. If it is not case 1 and with sampling frequency > 25 MHz: 21.846 samples. (Air distance: 743 mm @ Sampling Frequency 10 MHz) 3. In other cases: 65.500 samples (Air distance: 2.230 mm @ Sampling Frequency 10 MHz)
Start Delay (Inhibition Time)	Programmable up to 26 ms, with 100 ns of resolution
Attenuator	Programmable 0 dB / – 20 dB

Signal processing: Real-time signal processing of acquired scan lines (Hardware Implemented)
Band-Pass filter with programmable cutoff frequencies 64 coefficients FIR implementation. – Constant response in the pass band (ripple < 0.1 dB) – High attenuation in the stop band (typ. > -50 dB)	(1)
Signed 16 bits format data
Acquisition information data in real-time: A-scan, B-scan, peak position and amplitude (gates), encoders count
3 hardware gates for the peak detection (Independent or linked): – gate type: Detection of the maximum, the minimum, the positive edge or negative edge. – start / end gate: Programmable from the first acquired sample to the last acquired sample. – threshold gate: Programmable (0 to 100 % screen)	(2)
3 software for the peak detection (Independent or linked): – gate type: Detection of the maximum, the minimum, the first peak over the threshold, the positive edge or negative edge. – start / end gate: Programmable from the first acquired sample to the last acquired sample. – threshold gate: Programmable (0 to 100 % screen)	(3)
Scan compression with Non-Peak-Loss compression algorithm, up to 128:1 compression rate.
Programmable down-sampling factor from 4096 to 1 (equivalent sampling frequencies between 24 KHz and 100 MHz)
Digital Envelope detection, implemented by Hilbert Transform.
EMI Filter, 2 to 5 A-Scan signals – Removes, in real-time, the impulsive noise. – Improves flaw detection and reduces the production of false alarms. – Keeps a high dynamic range in noisy environments for C and D-scans.
Average (2, 4, 8, 16, 32, 64, 128, 256)

2. Software

DASEL provides the «UTView» application to configure all the acquisition parameters, as well to show, save and load the A-Scan signals acquired by the system. This application also allows getting B-Scan and C-Scan images triggering with an encoder or an external signal.

• Simultaneous acquisition of multiple images CD-Scan
• Access to data cube (C, B, A-Scan), for post-processing.
• Registration of A-Scan signals, B-Scan and C-D-Scan images, position encoders and detection gates (pick and position).

All the data acquired with the «UT-View» application can be loaded from MatLab, to make a post processing.

DASEL also provides a programming library to operate the system from MatLab, LabView, Python, Visual Studio, Borland C++, etc.

This library offers the functions set to configure all the acquisition parameters, and get the acquisition data.

The «UT-View» application and the programming library are available to run in Windows 32/64 bits (Windows 10 / Windows7)

This application also provides the necessary tools to analyze acquired images:

• Measurement cursors to get distances, time of flight, signal amplitude, etc.
• Different types of gates to generate different C-Scan images of position and amplitude.
• Frequency analysis of the signal in magnitude and phase.
• Reporting.