Laser Vibrometers

Name ChannelsBandwidthWorking DistanceLaser ClassDatasheet
VSM1000 1 from DC up to 50 kHz Autofocus (20 - 120 cm) 2
VSM4000 up to 4 from DC up to 50 kHz Autofocus (20 - 120 cm) 2
VSM1000-EXT 1 from DC up to 3 MHz Autofocus (20 - 120 cm) 2
VSM4000-EXT up to 4 from DC up to 3 MHz Autofocus (20 - 120 cm) 2
VSM1000-L 1 from DC up to 50 kHz Autofocus (50 - 500 cm) 2
VSM4000-L up to 4 from DC up to 50 kHz Autofocus (50 - 500 cm) 2
VSM1000-L-EXT 1 from DC up to 3 MHz Autofocus (50 - 500 cm) 2
VSM4000-L-EXT up to 4 from DC up to 3 MHz Autofocus (50 - 500 cm) 2
VSM4000-L-EXT-3D 3 from DC up to 3 MHz Autofocus 2
VSM3D 3 from DC up to 50 kHz Fixed (15 cm) 2
VSM1000-(L)-(EXT)-SCAN 1 from DC up to 3 MHz Autofocus (50 - 500 cm) - Scanning 2
VSM-3D-SCAN-(L)-(EXT) 3 from DC up to 3 MHz Autofocus (50 - 500 cm) - Scanning 2

Julight Laser Vibrometers are based on the novel Self-Mixing interferometric configuration, and  allow easy and accurate non–contact vibration measurements on all rough and diffusive surfaces (e.g.: unfinished metal, plastic, rubber, paper, fabric, etc.), and are also suited for underwater operation.

A very small optical head is the distinctive feature of Julight Laser Vibrometers, with size of 105mm x 70mm x 50mm, including Autofocus and Speckle-Tracking functionalities.

Julight Laser Vibrometers provide an analog electrical output which is a replica of the target displacement (with 0.5 mV/µm responsivity, corresponding to  2 mm/V) or velocity (5 V/(m/s) responsivity, corresponding to  0.2 (m/s)/V).

The frequency range of the measurable vibrations for standard models goes from DC up to 50 kHz, and an extended measuring band from 20 kHz up to 3 MHz is available with the -EXT option. Upon customer request, the upper band limit can be further extended to 10 MHz.

The minimum measurable displacement is as small as 0.2 nm (for 1 Hz noise bandwidth) for short-distance operation. A peak-to-peak maximum vibration amplitude larger than 1 mm can easily be measurable, and up to 5mm for good target surface quality. The maximum measurable velocity is 0.5 m/s in the standard bandwidth, and it reaches 40 m/s in the ultrasound extended bandwidth.

The VSM series includes single-point vibrometers with single optical head (VSM-1000) and the VSM-4000 model that can host up to four measuring channels with 4 independent optical heads. The VSM-4000 allows to perform simultaneous vibration measurements on different points of the same object, and to perform 3D vibration measurement.

More evoluted Laser Vibrometer models include the 3D version (VSM 3D), and the VSM-1000-SCAN scanning Laser Vibrometer.

USE

The optical head shall be placed in front of the vibrating surface, at a working distance between 0.2 m and 1.2 m (between 0.5 m and 5.0 m with the -L option). The Autofocus function allows the instrument to automatically adapt to the effective working distance. The vibration signal is then readily available from the BNC output connector of the electronic unit. The output vibration signal can be supplied to an oscilloscope or to an acquisition system to carry out FFT analysis in the frequency domain.
LED-bar indicator measures the strength of the optical signal back-scattered by the target surface, and an Automatic Speckle-Tracking System helps to avoid signal fading caused by speckle–pattern effects.

APPLICATIONS

•    Non-contact measurement of displacement and vibrations
•    Vibration measurement without mass-loading on small, soft and delicate structures
•    Material and structural analysis
•    Automotive, aerospace and energy industry (engines and turbines monitoring, validation tests…)
•    Loudspeaker, piezoceramic an MEMS testing/characterization
•    Modal analysis
•    On–line process control in industrial plants
•    Machine Condition Monitoring
•    Quality tests

Vibro_DiagrammaAmpFreq_20151114_200_1000pm_0_5_0_2_ms_US_3MHz

Measurable vibrations for the VSM series Laser Vibrometers.
RED: standard frequency range (0 Hz – 50 kHz).
BLUE: Extended frequency range (20 kHz – 3 MHz). This range can be further extended up to 10 MHz, upon customer request.
SOLID LINES: standard operating distance range: 0.2 m – 1.2 m.
DASHED LINES: long operating distance range (option -L): 0.5 m – 5.0 m. This range can be further extended up to 20 m, upon customer request (with laser safety Class 3B instead of Class 2).