Content Comparison

The rotation stage is accessible on the outside of the Calibration Bench, and mechanically this is a straightforward change. The difficulty lies in re-aligning the fold mirror mounted on the rotation stage, so that is directs the light from all sources onto the various fibers.

None

• At best this would allow use of only one calibration source.

• However, it would likely take the entire Calibration Unit off-line

• We would not be able to calibrate the main spectrometer and monitor instrument drift.

Aux Rack

Cryostat Ion Pumps

Gamma 3SDI1V5KNN (3S TiTan)

4x

$770 /
6-7 weeks

Requires warming up CCDs, venting main spectrometer vacuum chamber, and removing the large camera-access flange on the side of the vacuum chamber. The ion pumps can be “re-conditioned” at WMKO and re-used.

500 hours at 1e-4mbar

5,000 hours at 1e-5mbar

50,000 hours at 1e-6mbar

500,000 hours at 1e-7mbar

None

Each cryostat has two ion pumps.

• If one fails:

  Status
  colour Green title small impact

• If both fail:

  Status
  colour Red title major impact

  • CCD thermal control will be lost

Computer

*updated*

kpfserver

ASL Lancelot
2884-SRT

1

$10k /
1 week (in 2021)

Backup computer already installed within KPF Calibration Rack. When switching to the backup computer, the USB cable for the Exposure Meter detector needs to be moved from kpfserver to the backup computer.

However the WMKO-standard OS and files need to be installed.

1 spare

• If kpfserver goes down, we lose remote control of the instrument (and all telemetry)

FIU

*updated*

Science ADC or HK ADC Controller

Micronix
MMC-100-PCB Piezo Motor Controller Board

3

Controllers sit within AO Rack on top shelf. Access to controllers is somewhat constrained as the rack door does not fully open. The spares are a PCB board (only) that needs to be installed within an existing MMC-100 controller enclosure.

Works with either the PR-50 rotary ADC stages (science arm) or the PPX-32 linear ADC stages (HK arm).

2 spares

If Science ADC fails:

• ADC correction would be impossible, leading to loss of blue and red flux within science spectra. Radial velocity precision would be impacted.

If HK ADC fails:

• HK Spectrometer throughput would suffer, perhaps to the point that spectra were not useable.

• Main spectrometer would be unaffected.

FIU

*updated*

Calibration Mirror Linear Stage Controller

Micronix MMC-200-01110 stepper motor controller

1

Controllers sit within AO Rack on top shelf. Access to controllers is somewhat constrained as the rack door does not fully open, but still a relatively straightforward replacement.

1 spare

If controller failed while mirror was out-of-beam:

• We would not be able to calibrate the main spectrometer and monitor instrument drift.

If it failed in-beam:

• Light from the telescope would be blocked.

FIU

*updated*

Front Hatch

Uniblitz NS45B1T1 Shutter

1

$960 /
4-5 weeks

FIU does not need to be removed for this shutter to be replaced. The replacement shutter does need to have it’s in-line 5-pin SwitchCraft connector replaced with a right-angled version.

1 spare

If it fails closed:

• no telescope light can reach KPF

If it fails open:

• FIU could be used at night, but is no longer protected from dust during the day, and is no longer light-tight to the rest of the AO system (day or night)

LN2 Cart

*updated*

Autofill System

2x solenoids

The solenoids and other components are accessible on the LN2 cart in the basement. Marked as medium difficulty given there is some risk involved, as care must be taken to avoid water vapor getting into the lines (leading to ice blocking the lines). If ice blocks the lines then the CCD must be warmed up and the lines purged (with a major disruption to the instrument stability timeline).

3x Solenoids

Also shared spares available for:

• Maple PLC (and HMI and I/O modules

• temperature sensors

• pressure transducers

• CCD thermal control cannot be maintained without LN2 in the KPF dewars. The CCD will start to warm up.

Aux Rack

LN2 Pumps

Instec LN2-SYS

2x

The pumps are easily accessible on the LN2 cart in the basement. Marked as medium difficulty given the steps involved:

• power down the appropriate Instec controller;

• connect the new pump and power it on;

• turn the Instec controller back on;

• ensure Instec set point is correct and temperature control enabled.

There is also some risk involved, as care must be taken to avoid water vapor getting into the lines (leading to ice blocking the lines). If ice blocks the lines then the CCD must be warmed up and the lines purged (with a major disruption to the instrument stability timeline).

1 brand-new spare;
1 used spare

• CCD thermal control cannot be maintained with the LN2 pump running. The CCD will start to warm up.

Aux Rack

Instec Controller

Instec mK2000B

2

$5000 / 4-6 weeks

The pumps are easily accessible on the LN2 cart in the basement. Marked as medium difficulty given the software steps involved:

• power down the appropriate Instec controller and disconnect cables;

• connect the new controller and power it on;

• ensure Instec set point is correct and temperature control enabled.

1 spare has been ordered

• CCD thermal control cannot be maintained without the Instec system running. The CCD will start to warm up.

Fiber System

Scrambler Timed Shutter

Uniblitz NS65B

1x

$1,280 /
4-5 weeks

This shutter is designed to be easily removable from the scrambler. Marked as medium difficulty given time required to open the enclosure to access the shutter, and care required while working around exposed optics and fibers.

Consumable item.

1 spare

• This shutter controls the exposure time of the main spectrometer. Would not be able to take spectra until shutter is replaced.

Cal Unit

Shutters

Uniblitz DSS25B

6x

(2x Cal Bench,
1x Flat Field, 2x SoCal,
1x HK)

$540 ea /
4-5 weeks

The various shutters are designed to be easily removable from their mounts. Marked as medium difficulty given time required to open the enclosure to access shutter, and care required while working around exposed optics and fibers.

Consumable item.

3 spares

If the Calibration shutters fail:

• We would no longer be able to calibrate the main spectrometer or track instrument drift.

If the SoCal, HK Spectrometer, or Flat Field Fiber shutters fail:

• The main spectrometer would be unaffected.

LFC

Photonic Crystal Fiber (PCF)

Menlo Systems

1

Brett Smith (WMKO) installed the replacement when the PCF failed. He said it took about an hour, but one needs to be slow and methodical. Covers, module, output fibers are removed one of which, the IR, is in a tight space. PCF module location is set by pins.

Consumable item.

None

• LFC cannot be used until replaced. Calibrations will have to lean more heavily on the etalon and the HCL lamps while LFC down; could compromise tracking of instrument stability

Cal Unit 

Etalon Super Continuum

NKT SuperK EVO

1x

$33.5k for new device, $8.5k to refurbish existing device. Lead time: 4-6 weeks.

The SuperK is easily accessible within Etalon Rack.

Consumable item.

None

• If etalon not available, calibrations will have to lean more heavily on the LFC and the HCL lamps.

• Using the LFC instead of the etalon is more expensive, as it leads to more frequent PCF fiber replacements in the LFC.

Exposure Meter

Exposure Meter Detector

SBIG Aluma 47-10

1x

$15k /
6-8 weeks

Requires opening the Exposure Meter enclosure. Detector is on mounting that is designed to be removable.

None

• Main spectrometer would remain operational, however, ability to monitor flux within science exposures would be lost. RV quality would suffer because precise exposure midtimes could not be computed.

Fiber System

Agitator Motor

Galil BLM-N23-50-1000-B

1x

$500 /
1-2 weeks
(in 2018)

Motor is accessible on the outside of the agitator. A flex coupling is used between the motor and the agitator mechanism, so no careful alignment required. Marked as medium difficulty given the agitator is located within the crypt (not easily accessible and potential permits required).

None

• Observations could continue however the radial velocity precision will be impacted.

FIU

H&K Fiber Stage

Micronix PPX-32CR-C0002

1x

$4,500 ea / 10-12 weeks

Requires:

• removing FIU from AO Bench,

• opening FIU,

• removing Ca HK fibers from stage,

• removing stage from FIU.

None

• Throughput of Ca HK spectrometer would diminish, likely to a point were spectra do not have enough flux to be useful.

• Main spectrometer and rest of system would be unaffected.

Ca HK

Ca HK Detector

Andor Newton 920 (with UV-optimized CCD)

1x

$37k / 12 weeks

Requires opening Ca HK Spectrometer (after swinging it to a horizontal state).

None

• Ca HK Spectrometer would not be usable if detector failed.

• Main spectrometer and rest of system would be unaffected.

Cal Unit

Broadband Source 

Thorlabs SLS201L

2x

(1x Octagon, 1x Flat Field)

$1,200
No lead (June 2023)

The broadband sources are easily accessible under the Calibration Bench.

Consumable item.

None

• Would lose some calibration ability but could rely on past calibrations until replacement available. (True?)

Cal Unit

Filter Wheel

Thorlabs FW102C

3x

(1x Octagon, 1x Flat Field)

$1,300
No lead (June 2023)

Mechanically the filter wheels are easy to remove with no careful alignment requirements. Marked as medium difficulty given the care required to avoid damaging the bare optical fibers within the Calibration Unit enclosure.

None

• Would require a change in calibration strategy (and scripts) but could likely carry on until replacement filter wheel arrived.

Cal Unit

ThAr Lamp

Green Scientific G858A

2x

(1x Daily,
1x 'Gold')

$405

The lamps are easily accessible on the exterior of the Calibration Unit.

Consumable item.

No current spares

6 are on order

* updated *

If one lamp fails:

• we can rely on the other lamp of the same type until replacement arrives.

If both lamps of the same type fail:

• we lose ability to wavelength-calibrate daily, and will have to rely on past calibrations. Radial velocity precision might be impacted.

Cal Unit

UNe Lamp

Photron P863

2x

(1x Daily,
1x 'Gold')

$825

The lamps are easily accessible on the exterior of the Calibration Unit.

Consumable item.

4 spares

Cal Unit

HCL Power Supply

Photron P209 Hollow Cathode Lamp Power Supply

and

Green Scientific G200

4x

(1x Th-Ar Daily,
1x Th-Ar Gold,

1x U-Ne Daily, 1x Un-Ne Gold)

Green Scientific Supply:

$730

The HCL power supplies are easily accessible within the Calibration Rack.

1x Green Scientific Power Supply

If one supply fails:

• we can rely on the other lamp of the same type until replacement arrives.

If two supplies of the same type fail:

• we could swap supplies around to have one lamp of each type operational until replacement arrives.

If three supplies fail:

• we lose ability to wavelength-calibrate daily, and will have to rely on past calibrations. Radial velocity precision might be impacted.

Fiber System

Scrambler Source Select Shutter

Uniblitz RS20B

2x

$550 each (minimum quantity was 10 last time we ordered). Lead time: 5-6 weeks

These shutters are designed to be easily removable from the scrambler. Marked as medium difficulty given time required to open the enclosure to access the shutters, and care required while working around exposed optics and fibers.

Consumable item.

10 spares

• If one of these shutters fails in a closed state, that light path (Science or Sky) cannot be used until the shutter is replaced.

Cal Unit

Intensity Monitor Stage

Newmark MSL-50-21

1x

$1,100

Mechanically the stage is easy to remove, and the intensity monitor detector is simply mounted (on a post with no careful alignment requirements). Marked as medium difficulty given the care required to avoid damaging the bare optical fibers within the Calibration Unit enclosure.

None

• If stage failed out-of-beam, it could stay there until replaced.

• If stage failed in-beam, it could be removed from system until replacement is available.

Vac Cart

Isolator Stepper Motors

Lin Engineering 4118M-06S-22RO

5x

Requires warming up CCDs, venting main spectrometer vacuum chamber, and opening chamber door(s) to gain access to the motors under the optical bench. Depending on the motor’s location, the Vac Cart, Aux Rack and LN2 Autofill system might need to be disconnected and moved out of the way so the chamber door can open.

Used very infrequently (mainly for initial alignment of bench or realigning after a significant earthquake). Powered off when not in use.

None

• Loss of one motor could likely be compensated for through adjustment of the other four.

• It is very unlikely we would vent the chamber only to replace one of these motors.

Cal Unit

Compensator Motor

Newport TRA12PPD

4x
(2x BS,
2x Fold)

Need TBD