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Longitudinal Mode Measurement——Scanning F-P Interferometer |
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Laser
longitudinal mode refers to the axial
distribution of the light field along to
its direction of propagation. An
ordinary laser usually has a few or dozens of longitudinal modes. Using high
resolution spectrometer to test the laser spectrum, there will
be multiple laser frequencies (or wavelengths). If restraining
most of the longitudinal modes through selecting frequencies and
just retaining one of them, then we could get single
longitudinal mode (single frequency) laser.Single longitudinal laser compares with ordinary
laser, has narrower line width and coherence length. It is
widely used in spectrum analysis, holographic imaging, interferometry and other fields.
Scanning Fabry-Perot interferometer is a kind of
spectrum analyzer, which is suitable for
detecting the subtle spectral
characteristics of continuous lasers. It
mainly includes sawtooth signal
generator, Fabry-Perot interference
cavity, and high-speed photodetector. |
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Testing Instrument: Scanning
F-P
Interferometer |
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Confocal
Fabry-Perot Design
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The
reflectance of the lens remains
above 99% in the range of 532-633 nm
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Photodiode Detector Included
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Free
Spectral Range: 2.5 GHz
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Minimum
Finesse: 200
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Model |
Wavelength Range |
Free
Spectral Range |
Total Finesse |
Resolution |
Cavity Length |
Mirror Substrate |
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FPSI 200-532 |
532-633 nm
(Other wavelengths can be
customized) |
2.5GHz |
≥200 |
<12.5 MHz |
30
mm |
UV
Fused Silica |
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Scanning
F-P Controller Box |
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Sawtooth
Scan Voltage
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For
Piezoelectric Transducer
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Scan the
Separation between the Two Cavity
Mirrors
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High
voltage signal duty cycle and
amplitude adjustment range are
adjustable.
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Oscillogram |
Output Voltage Range |
Frequency Conversion |
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Sawtooth |
0-200V |
0.05/ 0.1/ 0.5/ 1/5 s |
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Examples
of Testing Results |
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Single longitudinal mode
testing |
Multiple longitudinal
modes testing |
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