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7J20: Difference between revisions
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m (→top: clean up, replaced: {{Plugin Sidebar 2 → {{Plugin Sidebar , series=7000-series scopes| → series=7000-series scopes|, title=Tektronix → manufacturer=Tektronix | type=) |
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* [[Media:Peter burke fast-scan spectrometry.pdf|Peter Burke "Fast-Scan Spectrometry" (PDF)]] | * [[Media:Peter burke fast-scan spectrometry.pdf|Peter Burke "Fast-Scan Spectrometry" (PDF)]] | ||
}} | }} | ||
The '''Tektronix 7J20''', which only appears in the 1975 catalog, is a "rapid scan" optical spectrometer for the 250 nm to 1100 nm region. | |||
The '''Tektronix 7J20''', which only appears in the 1975 catalog, | Rapid scan means that it can capture the spectrum quickly enough to show spectral changes at temporal resolution of a few milliseconds. | ||
is a "rapid scan" optical spectrometer for the 250 nm to 1100 nm region. | |||
Rapid scan means that it can capture the spectrum quickly enough | |||
to show spectral changes at temporal resolution of a few milliseconds. | |||
The spectrometer is packaged in two enclosures linked by an umbilical cable. | The spectrometer is packaged in two enclosures linked by an umbilical cable. | ||
The 7J20 is a 2-wide plug-in for [[7000-series scopes]] containing the sweep timing and mainframe interface circuits. | The 7J20 is a 2-wide plug-in for [[7000-series scopes]] containing the sweep timing and mainframe interface circuits. | ||
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==Internals== | ==Internals== | ||
The instrument is based on a [[wikipedia:Monochromator|Czerny-Turner Monochromator]], | The instrument is based on a [[wikipedia:Monochromator|Czerny-Turner Monochromator]], in essence a narrow slit followed by a [[wikipedia:Diffraction grating|diffraction grating]]. | ||
in essence a narrow slit followed by a [[wikipedia:Diffraction grating|diffraction grating]]. | A [[wikipedia:Vidicon|vidicon tube]] scans the optical spectrum and produces a periodic electric signal which is then displayed by the scope mainframe. | ||
A [[wikipedia:Vidicon|vidicon tube]] scans the optical spectrum | |||
and produces a periodic electric signal which is then displayed by the scope mainframe. | |||
[[File:7J20-principle.jpg | thumb | 400px | center | Operating principle (click to enlarge) ]] | [[File:7J20-principle.jpg | thumb | 400px | center | Operating principle (click to enlarge) ]] | ||
The internal vidicon horizontal scan voltage corresponds to wavelength, | The internal vidicon horizontal scan voltage corresponds to wavelength, but not in a linear way. | ||
but not in a linear way. | To provide a linear nm/div horizontal display on the 7000-series mainframe, the vidicon horizontal scan signal is passed through a function generator IC, the [[155-0106-00]] (U1550 and U1590), which implements an interpolated lookup table. | ||
To provide a linear nm/div horizontal display on the 7000-series mainframe, | Inside the J20, there are 40 trimmer potentiometers that allow the lookup function to be tweaked so that the horizontal scale of the system is accurate. | ||
the vidicon horizontal scan signal is passed through a function generator IC, | |||
the [[155-0106-00]] (U1550 and U1590), | |||
which implements an interpolated lookup table. | |||
Inside the J20, there are 40 trimmer potentiometers that allow the lookup function to be tweaked | |||
so that the horizontal scale of the system is accurate. | |||
[[File:Tek_j20_interim_normalizer2.png | thumb | 400px | center | Normalizer (click to enlarge) ]] | [[File:Tek_j20_interim_normalizer2.png | thumb | 400px | center | Normalizer (click to enlarge) ]] | ||
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Tektronix-J20 UV Fiber Optic Sensor-Ring Adpater-Side-hires.JPG |J20 Mounting Ring Adapter Side | Tektronix-J20 UV Fiber Optic Sensor-Ring Adpater-Side-hires.JPG |J20 Mounting Ring Adapter Side | ||
</gallery> | </gallery> | ||
{{Custom ICs|7J20}} | |||
{{Custom ICs|J20}} | |||
[[Category:7000 series combined plugins]] | [[Category:7000 series combined plugins]] | ||