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Table of Contents:
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Introduction
The Laser Frequency Comb (LFC) is a ‘black box’ system purchased from Menlo Systems. It provided a high-line density calibration source for KPF that offers high wavelength stability,
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Relevant Devices
Description | Qty | Source | Part Number |
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Menlo Laser Frequency Comb |
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Relevant Functional Block Diagram
Software Actions
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Action
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Notes
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Required Adjustable Settings
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Setting
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When Needed
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Notes
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Build
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Observing
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Maintenance
Required Telemetry
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Parameter
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Report Frequency
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Purpose
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Notes
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f_rep
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Used to define comb output frequencies
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f_0
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Used to define comb output frequencies
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Required Alarms
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Parameter
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Threshold
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Notes
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Relevant Datasheets & Manuals
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Description
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File
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Source
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XML Manual
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Should be supplied by Menlo
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Relevant Software
From Sam:
“Hi Steve,
We will need to query the LFC desktop for (at least) two pieces of telemetry -- f_rep and f_0, which fully define the output frequencies of the comb. These need to be saved in each FITS header to derive the absolute wavelength solution and also tell the act as a flag for whether or not the comb is locked. There are also a few other health-check metrics that can be stored, such as the comb lock status.
For NEID, I believe the Astrocomb computer is queried via XML to send a set of telemetry values, which the NEID server then stuffs into the FITS header of the observation. I'm not too familiar with this telemetry handoff (sorry), but there is a specific manual that we will get with the comb delivery that outlines the command protocols and query-able data products.
Is that what you were asking? I can also see if I can find the NEID LFC XML manual, if this would help give a sense of the complexity.
Sam”Note the LFC computer will sit on the Keck ‘ops’ network at the summit, not the KPF private network.
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Relevant Datasheets & Manuals
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Relevant Software
The Menlo LFC uses websockets to communicate with other processes.
Menlo has written an API layer in Python that has two requirements:
Menlo also suggests that you can use
with pywebchannel but you have to roll your own interface.
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Dispatcher
Keyword | Value | Type |
|---|---|---|
AMPLIFETIME | 22.004 sec | Float |
DEVICE(#) | Menlo LFC - device name AstroComb_AU06112 | String |
PCFSERIAL | ####### - serial number of PCF | String |
OPERATIONMODE | 0 - AstroComb (or On) 1 - StandbyHi (preferred when not in use) 2 - StandbyLow 3 - Off 4 - Manual | Enumerated Values 2 through 4 are NOT writeable. |
IRFLUX | 13451234 | Integer - no units |
VISFLUX | 12341234 | Integer - no units |
OFFSETFREQ | 135928345 Hz | Double |
LFCCEOFR | -30000000.00 Hz CEO filtered setpoint | Double |
LFCCWFERR | 34412342 Hz CW frequency error | Double |
LFCCWFREF | -30000000 Hz CW reference frequency | Double |
LFCCWFREQ | 288005504412342 Hz CW frequency | Double |
LFCCWMDN | 0 | Integer |
LFCF0 | 250000163.02 Hz LFC filtered offset frequency | Double |
LFCFOREF | 250000000.00 Hz LFC filtered offset freq ref | Double |
LFCFRR | 20000013041.2758 Hz LFC Filtered Rep Rate | Double |
LFCFRREF | 20000000000.0000 Hz LFC Filtered Rate Ref | Double |