Calibration Unit Filter Wheels

Table of Contents:

1 Introduction
2 Relevant Devices
3 Relevant Functional Block Diagram
4 Cable Details
5 Look-up Tables for Filter Positions
- 5.1 Filter Wheel: ND1 “Octagon” (All Calibration Fibers)
- 5.2 Filter Wheel: ND2 “Simul Cal” (Simult. Cal. Fiber Only)
6 Relevant Datasheets & Manuals

Introduction

Two filter wheels are employed in the calibration unit. Both are populated with six neutral-density filters that are used to adjust the amount of calibration flux reaching the main spectrometer.

Calibration Unit section of the KPF System Overview diagram.

The “Octagon” (or ND1) filter wheel is used to tune the amount of flux injected into all of the calibration fibers. The sources within the octagon vary in intensity, and this filter can be used to minimize flux differences between sources.

The “Simul Cal” (or ND2) filter wheel is used to tune the amount of flux injected into the Simultaneous Calibration fiber only. Because the Simultaneous Calibration fiber is used during science exposures, its flux output must be adjusted to match that of the science target (otherwise the calibration spectrum would be over-exposed). Since both the Octagon and Simul Cal ND filter wheels affect the light reaching the Simultaneous Cal fiber, there are 36 combinations of filters possible for matching the simultaneous cal flux with that of the science target.

Relevant Devices

Descriptions	Qty	Source	Part Number	Notes

Descriptions

Qty

Source

Part Number

Notes

Filter Wheel

2

Thorlabs

FW102C

RS-232 connectivity

RS-232 to Ethernet Adapter

1

Lantronix

UDS2100

This is the version with two serial ports (and standard 9-pin RS-232 connectors)

Smaller Footprint Power Supply for Lantronix

1

Tri-Mag, LLC

Tri-Mag PN: L6R12H-120

DigiKey PN: 364-1264-ND

The stock Lantronix power supplies do not work well with the PDUs (as they block two extra outlets). KPF uses these replacement supplies since they only take up one PDU outlet.

Relevant Functional Block Diagram

Cable Details

Cable	Qty	Details	Notes

Cable	Qty	Details	Notes
Ethernet	1	Cat6 Copper Ethernet Cable M-M, 6 feet long	Entirely within Cal Rack.
Cal Unit - Filter Wheel Power	2	See https://keckobservatory.atlassian.net/wiki/spaces/KPFElectronics/pages/1511915635	DC Barrel Extension Cable Female-Male 5.5 mm OD x 2.1 mm ID
Cal Unit - Filter Wheel RS-232	2	See https://keckobservatory.atlassian.net/wiki/spaces/KPFElectronics/pages/1511915635

Look-up Tables for Filter Positions

Filter Wheel: ND1 “Octagon” (All Calibration Fibers)

Position	Filter Short Name	Filter Vendor	Vendor Description	Vendor Part Number

Position	Filter Short Name	Filter Vendor	Vendor Description	Vendor Part Number
1	OD 0.1	Thorlabs	Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 0.1	NDUVW01B
2	OD 1.0		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 1.0	NDUVW10B
3	OD 1.3		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 1.3	NDUVW13B
4	OD 2.0		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 2.0	NDUVW20B
5	OD 3.0		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 3.0	NDUVW30B
6	OD 4.0		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 4.0	NDUVW40B

Filter Wheel: ND2 “Simul Cal” (Simult. Cal. Fiber Only)

Position	Filter Short Name	Filter Vendor	Vendor Description	Vendor Part Number

Position	Filter Short Name	Filter Vendor	Vendor Description	Vendor Part Number
1	OD 0.1	Thorlabs	Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 0.1	NDUVW01B
2	OD 0.3		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 0.3	NDUVW03B
3	OD 0.5		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 0.5	NDUVW05B
4	OD 0.8		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 0.8	NDUVW08B
5	OD 1.0		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 1.0	NDUVW10B
6	OD 4.0		Unmounted Ø25 mm Wedged UVFS Reflective ND Filter, OD: 4.0	NDUVW40B

Relevant Datasheets & Manuals

	Description	File	Source

	Description	File	Source
1	Device Manual		https://www.thorlabs.us/newgrouppage9.cfm?objectgroup_id=988&pn=FW102C#2926
2	Software Manual		https://www.thorlabs.us/newgrouppage9.cfm?objectgroup_id=988&pn=FW102C#2926
3	SDK		https://www.thorlabs.us/software_pages/viewsoftwarepage.cfm?code=FW102C
4	Lantronix UDS 2100 Quick Start Guide		https://www.lantronix.com/products/uds2100/#tab-docs-downloads
5	Lantronix UDS 2100 User Guide		https://www.lantronix.com/products/uds2100/#tab-docs-downlo
6	Smaller Footprint Power Supply Datasheet		https://www.tri-mag.com/wp-content/uploads/2021/05/L6R12H_Series_2021-01.pdf (Linked off the DigiKey product page)

KPF Electronics