7J20: Difference between revisions

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* [[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 7J20 is a 2-wide plug-in for [[7000-series scopes]] containing the sweep timing and mainframe interface circuits.

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==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) ]]

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) ]]

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Tektronix-J20 UV Fiber Optic Sensor-Ring Adpater-Side-hires.JPG |J20 Mounting Ring Adapter Side

</gallery>

[[Category:7000 series combined plugins]]

@@ Line 20: / Line 20: @@
 * [[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 7J20 is a 2-wide plug-in for [[7000-series scopes]] containing the sweep timing and mainframe interface circuits.
@@ Line 31: / Line 28: @@
 ==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) ]]
-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) ]]
@@ Line 92: / Line 82: @@
 Tektronix-J20 UV Fiber Optic Sensor-Ring Adpater-Side-hires.JPG |J20 Mounting Ring Adapter Side
 </gallery>
+{{Custom ICs|7J20}}
+{{Custom ICs|J20}}
 [[Category:7000 series combined plugins]]

7J20: Difference between revisions

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