Attachment B - Laser Head Requirements Document (1).pdf

LISA Laser Head Requirements Document

REQUEST FOR INFORMATION - SOURCES SOUGHT FOR

THE LASER INTERFEROMETER SPACE ANTENNA (LISA)

Solicita(on Number: 80GSFC24XXXRFI

Requirement ID Requirement Title Requirement Verification

Method

5.1 Functional requirements

LS.FUN.00010 Laser light for interferometry The LS shall provide the laser light with performance meeting the interferometric measurement needs.

T

LS.FUN.00020 Laser light modulation The LS shall superimpose the modulations required for ranging, clock correction, and data transfer, as generated by the phasemeter, on the provided laser light.

T

LS.FUN.00030 OBA power measurement The LS shall provide a measurement of the power with at least 1 Hz sampling frequency and at least 1E-4 precision at 0.1 mHz.

T

LS.DES.00220 Payload calibration support

The LS shall support the payload calibration activities and measurement, by providing in particular:

• Absolute frequency determination

• Adjustable power levels for interferometer calibration

• Frequency modulation around set point for TDI calibration

R, T

LS.DES.00430 Timestamped telecommand execution The LS shall be capable of receiving, storing and implementing telecommands for execution at a defined timestamp based on spacecraft internal time.

R, T

LH.Req.Des.80 Laser System Operational Modes

The LS shall have the following operational modes:

Mode 0: Off Mode 1: Stand-by Mode 2: Safe Mode Mode 3: On Mode 4: Free-running Mode 5: Diagnostic Mode 6A: Reference Mode 6B: Frequency Modulation Mode 7: Transponder Mode 8: Amplitude Modulation

Note: Each LH of the constellation shall be independently commandable to any mode. Only a single LH at a time shall be in Mode 8. LH mode selection is controlled by the SC OBC.

R, T

LH.Req.Des.81 Mode 0: Off

Power consumption: None Available TM: None Data rate to OBC: None Mode description: In this mode the LS shall consume no electrical power, shall provide no telemetry, shall be able to transition to Mode 1 when commended via TC by the OBC. The LS unit non-operational temperature will be ensured by the SC through dedidated heaters provided by the SC and mounted on the LS units.

Allowed transitions from this mode:

• Mode 1

R, T

LH.Req.Des.82 Mode 1: Stand-by

Power consumption: TBD Available TM: TBD Data rate to OBC: TBD Mode description: The OBC will command one LH in each LA into this mode. The LS shall command the FRS into Stand-by mode. In this mode the LH shall be ready able to receive TC from the OBC. In this mode laser HK TM shall be provided to the OBC.

Upon receipt of TC from the OBC the LH shall transition to Mode 3 with no waiting time.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions from this mode:

• Mode 0

• Mode 2

• Mode 3

R, T

LH.Req.Des.83 Mode 2: Safe Mode

Power consumption: TBD Available TM: TBD Data rate to OBC: TBD Mode description: Upon failure detection, the LS shall enter and remain within this mode. In this mode laser HK TM shall be provided to the OBC. The LS shall remain with this mode until receipt of TC from the OBC.

Allowed transitions from this mode:

• Mode 0

• Mode 1

R, T

LH.Req.Des.84 Mode 3: On

Power consumption: 99 W TBC Available TM: all at nominal resolution and sampling rate.

Data rate to OBC: 14 kbps Mode description: The OBC will command one LH in each LA into this mode. In this mode the LH shall emit laser light towards the OB; frequency and power stability requirements are not required to be met in this mode. The optical power on the OB shall be tuneable, according to LS.PER.PWR.00020, via TC from the OBC and measured on the OB by PMON and internally within the LH.

FRS shall be on and frequency scanning shall be possible.

In this mode the LH shall be able to receive TC from the OBC. LS HK TM shall be provided to the OBC.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions from this mode:

• Mode 1

• Mode 2

• Mode 4

• Mode 5

• Mode 8

R, T

LH.Req.Des.85 Mode 4: Free-running

Power consumption: 99 W TBC Available TM: all at nominal resolution and sampling rate.

Data rate to OBC: 14 kbps Mode description: In this mode the LH shall emit power in the performance power range (LS.PER.PWR.00010) towards the OB. Power on OB is controlled using in-loop PMON and the power stability requirement (LH.Req.Opt.150) shall be met. The free running frequency stability performance (LH.Req.Opt.91) shall be met. If in-loop power monitor fails the LH shall autonomously switch to out-of-loop sensor and communicate failure to system.

In this mode the LH shall be able to receive TC from the OBC. LS HK TM shall be provided to the OBC.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions:

• Mode 2

• Mode 3

• Mode 5

• Mode 6

• Mode 7

R, T

LH.Req.Des.86 Mode 5: Diagnostic

Power consumption: 130 W TBC Available TM: TBD Data rate to OBC: 400 kbps Mode description: In this mode the LH shall emit laser light towards the OB. The optical power on the OB shall be tuneable, according to LS.PER.PWR.00020, via TC from the OBC and measured on the OB by PMON and internally within the LH.

Performance requirements shall not be met.

In this mode the LH will be able to start a frequency scan, and/or acquire high resolution and sampling rate telemetry of the FRS photodetectors. In this mode the PMON shall be on and the PMON control loop telemetries shall be accessible at high resolution, and sampling rate.

In this mode the LH shall provide to OBC the relevant telemetries as required for diagnostic purposes.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions:

• Mode 2

• Mode 3

• Mode 4

• Mode 7

R, T

LH.Req.Des.87 Mode 6A: Reference

Power consumption: 99 W TBC Available TM: all at nominal resolution and sampling rate Data rate to OBC: 14 kbps Mode description: In this mode the laser shall emit towards the OB in the performance power range (LS.PER.PWR.00010), meeting power (LH.Req.Opt.150) and frequency stability (LH.Req.Opt.93, LH.Req.Opt.94) requirements.

Upon receipt of OBC command the selected LH shall enter this mode automatically i.e. perform frequency scan and lock acquisiton autonomously. FRS is on and is used to control (via FRS-E, and LEM) the laser frequency. PMON are on and used to control the RIN (via LEM internal control loop). If in-loop power monitor fails the LH shall autonomously switch to out-of-loop sensor and communicate failure to system.

In this mode the LH shall be able to receive TC from the OBC. LS HK TM shall be provided to the OBC.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions:

• Mode 2

• Mode 4

• Mode 5

• Mode 6B

R, T

LH.Req.Des.89 Mode 6B: Frequency Modulation

Power consumption: 99 W TBC Available TM: all at nominal resolution and sampling rate Data rate to OBC: 14 kbps Mode description: In this mode the reference laser shall be locked on the FRS with a sinusoidally varying offset creating a frequency modulation as specified by LH.Req.Opt.25. In this mode the laser shall emit towards the OB in the performance power range (LS.PER.PWR.00010), meeting power (LH.Req.Opt.150) and frequency stability (LH.Req.Opt.93, LH.Req.Opt.94) requirements.

In this mode the LH shall be able to receive TC from the OBC. LS HK TM shall be provided to the OBC.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions:

• Mode 2

• Mode 3

• Mode 4

• Mode 5

• Mode 6A

R, T

LH.Req.Des.88 Mode 7: Transponder

Power consumption: 99 W TBC Available TM: all at nominal resolution and sampling rate Data rate to OBC: 14 kbps Mode description: In this mode the laser shall emit towards the OB in the performance power range (LS.PER.PWR.00010), meeting power (LH.Req.Opt.150) and frequency stability (LH.Req.Opt.93, LH.Req.Opt.94) requirements. In this mode the LH frequency control actuators shall be controlled by the PMS.

In this mode the LH shall be able to receive TC from the OBC. LS HK TM shall be provided to the OBC.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions:

• Mode 2

• Mode 4

• Mode 5

R, T

LH.Req.Des.90 Mode 8: Amplitude Modulation

Power consumption: 99 W TBC Available TM: all at nominal resolution and sampling rate Data rate to OBC: 14 kbps Mode description: In this mode the laser shall emit towards the OB in the performance power range (LS.PER.PWR.00010). The laser output power shall be modulated as follows:

a) Constellation acquisition sub-mode: the laser power shall be modulated sinusoidally by at most 20 dB peak to peak from a power in the performance power range at a frequency of 10 Hz. The mid point of the sinusoidal modulation shall be 1 W.

b) GRS calibration sub-mode: the laser power shall be modulated sinusoidally by at most 10% from a power in the performance power range at a frequency between 0.1 mHz and 100 mHz. The mid point of the sinusoidal modulation shall nominally be 1.8 W and the power step resolution shall be < 1 mW TBC.

In case of failure, the LH shall transition to Mode 2.

Allowed transitions:

• Mode 2

• Mode 3

R, T

5.2 Performance

5.2.1 Optical performance

5.2.1.1 Spectral Performance

LH.Req.Opt.10 Laser centre wavelength The centre wavelength, in vacuum, for the LS shall be in the range 1064.5±0.05 nm (or in frequency 2.81627E+14 Hz±13GHz).

T

LH.Req.Opt.60 Laser wavelength absolute knowledge The LH absolute wavelength shall be known to better than 1 part in 10,000 of the absolute wavelength over the nominal mission lifetime.

A

LH.Req.Opt.50 Laser frequency reproducibility The ground to space frequency reproducibility for a free-running LH (Mode 4) shall be 50MHz over the nominal mission lifetime.

A

LH.Req.Opt.15 Laser frequency tuning range commonality The laser heads shall allow tuning their output frequency in a mode-hop free fashion by at least ± 2 GHz, measured from an absolute laser frequency value, within the range and reproducibility specified by LH.Req.Opt.10 and LH.Req.Opt.50, that is identical for all laser heads.

T

LH.Req.Opt.25 Laser frequency modulation The LS shall, when set to Mode 6B, implement a sinusoidally varying offset creating a frequency modulation of amplitude between 2 Hz and 2 kHz, with step size of 10 Hz at a frequency between 1 mHz and 1 Hz.

T

LH.Req.Opt.80 Laser Wavelength Tuning Capabilities – Transponder Mode, fast actuation

The Laser Head shall provide the capability of fast actuation, mode-hop-free, continuous tuning. The fast actuation of the output laser frequency SHALL cover a range of ±50MHz and be compatible with a loop bandwidth (with which the frequency actuator must be compatible) of 30kHz.

NOTE this stipulates that LS.IF.PMS.00625 has to be met.

T

LH.Req.Opt.85 Laser Wavelength Tuning Capabilities – Transponder Mode, slow actuation

The Laser Head shall provide the capability of slow actuation mode-hop-free continuous tuning. The slow actuation shall be compatible with a unity gain of at least 1Hz. The maximum variation of frequency with a linear actuator response is expected to be of the order of 1MHz/s (TBC).

T

LH.Req.Opt.91 Laser frequency stability - free-running mode

The frequency stability for a free-running laser operating in Mode 4 shall be:

T, A

LH.Req.Opt.92 Laser frequency stability excess noise - free-running mode

The frequency stability excess noise for a free-running laser operating in Mode 4 shall be:

T, A

LH.Req.Opt.93 Laser frequency stability - reference mode

The frequency stability for a laser operating in reference mode (Mode 6A) shall be:

T, A

LH.Req.Opt.94 Laser frequency stability excess noise - reference mode

The frequency stability excess noise for a laser operating in reference mode (Mode 6A) shall be:

T, A

LA.Req.Opt.100 Laser spectral purity

The integrated power in a 10 nm band around the laser centre wavelength (LH.Req.Opt.100), excluding the laser line and a ±20 GHz band centred on it, shall be

• < 0.1% of the output power for light in the nominal polarization

• < 0.01% of the output power for light in the sum of all other polarisation states The integrated power, in the nominal polarisation, outside the 10 nm band around the laser centre wavelength shall be < 0.1%

A

LH.Req.Opt.101 Laser spectral purity - side-mode suppression ratio

The laser shall have a side-mode suppression ratio higher than 40 dB.

T, A

LH.Req.Opt.113 RF modulation The LS shall implement a phase modulation of the laser light at a modulation frequency of 2.400 ± 1% GHz.

T, A

LH.Req.Opt.114 RF modulation noise

The phase noise Sphi(f) and the excess noise δpp phi in the LISA frequency band (LS.DEF_PER_010) shall be:

T, A

LH.Req.Opt.115 RF modulation sideband power From a modulation input signal of between -8 dBm and -4 dBm, the laser shall ensure that the RF sidebands contain between 10 and 20% of the total laser power.

T, A

LH.Req.Opt.111 RF modulation modulation depth stability The RF sideband modulation depth shall not change by more than 10%, with respect to a constant input signal from the PMS, over the nominal mission lifetime.

T, A

LH.Req.Opt.120 PRN modulation The laser shall implement a phase modulation of the laser light with a PRN code with chip rate between 1Mbits/sec and 2Mbits/sec, with nominal rate 1.25 Mbits/sec.

T, A

LH.Req.Opt.121 PRN modulation sideband power From a modulation input signal of between TBC V and TBC V, the laser shall ensure that the PRN sidebands contain between 1% and 5% of the total laser power.

T, A

LH.Req.Opt.122 PRN modulation: modulation depth stability The PRN sideband modulation depth shall not change by more than 10%, with respect to a constant input signal from the PMS, over the nominal mission lifetime.

T, A

LH.Req.Opt.123 PRN modulation group delay The PRN modulation absolute group delay shall be less than 5µs. T, A

LH.Req.Opt.124 PRN modulation group delay stability The PRN modulation shall have a group delay stability of less than 1 ns over 24 hours.

T, A

LH.Req.Opt.125 PRN modulation rise time The PRN code modulation rise time shall be less than 20ns.

T, A

5.2.1.2 Power Performance

!! " < 3.75 () () 1 + 8 .()

"/0 0.12() ≤ " ≤ 14()

!!!" ≤ 30 '() *+, 1 () ≤ * ≤ 1 .()

!!!" ≤ 3 .() *+, 0.1 0() ≤ * ≤ 1 ()

1" * ≤ 30 () () 1 + 2 0()

*+, 0.10() ≤ * ≤ 1()

1" * ≤ 3.75 () () 1 + 8 '()

*+, 1() ≤ * ≤ 1.()

!!!" ≤ 50 '() *+, 0.1 0() ≤ * ≤ 1 ()

!!!" ≤ 200 '() *+, 1 () ≤ * ≤ 1 .()

1% * < 60 µ,:; ()⁄ 1 +700()* !!!= < 660,:;

LS.PER.PWR.00010 Laser performance power The laser shall emit a frequency (LH.Req.Opt.93) and power stabilised (LH.Req.Opt.150) power of 2 W at the output of the delivery optical fibre (LH.Req.Int.Opt.10), over the nominal mission lifetime.

T, A

LS.PER.PWR.00020 Laser operating power range The laser shall emit a non-stabilised (frequency or power) power in the range from 5- 10 mW to 2 W at the output of the delivery optical fibre (LH.Req.Int.Opt.10 ), over the nominal mission lifetime.

T, A

LS.PER.PWR.00030 Laser operating power adjustment via OBC TC

The laser operating power shall be settable via OBC telecommand. The setpoint is supplied in the following form:

Control bandwidth: 1 Hz Range and resolution: min to max of LS.PER.PWR.00020 in increments of 5 mW

(TBC).

I, R

LH.Req.Opt.135 Uncertainty of the absolute power from LS The power uncertainty at the output of the laser fibre (LH.Req.Int.Opt.10 ) shall be less than 10% (TBC) over the nominal mission lifetime.

A

LH.Req.Opt.140 Maximum power emitted towards the optical bench

The laser shall never emit an optical power greater than 2.5W at the output of the delivery optical fibre (LH.Req.Int.Opt.10), over all mission phases including AIT.

T, A

LH.Req.Opt.150 Output power stability

The output power stability at nominal power (LS.PER.PWR.00010) at the output of the delivery optical fibre (LH.Req.Int.Opt.10), over the nominal mission lifetime shall be less than (see Table 1).

The RIN noise shape function is defined in LS.DEF_PER_030.

T, A

LH.Req.Opt.160 Polarisation extinction ratio The polarisation extinction ratio at the output of the delivery optical fibre (LH.Req.Int.Opt.10), over the nominal mission lifetime shall be less than -20 dB.

A

LH.Req.Opt.170 Laser backscatter tolerance: continous The LH shall tolerate a continuous backscattered optical power of 10 µW (TBC) without any degradation of performance.

T, A

LH.Req.Opt.175 Laser backscatter tolerance: transient The LH shall tolerate a transient backscattered optical power of -15 dB for any output optical power without incurring any damage.

T, A

5.2.2 Mechanical properties

LH.Req.Mech.10 Mass Each LH including harnesses between LOM and LEM shall not exceed 19.2 kg, which includes 20% margin.

I, T

LH.Req.Mech.30 First eigenfrequency: LH The first eigenfrequency of the LH shall not be lower than 140Hz (TBC).

A

5.3 Interfaces

5.3.1 Optical Interfaces

LH.Req.Int.Opt.10 LH main optical output

The main optical output of the LH shall deliver laser light via a polarization maintaining, single-mode optical fibre with the following characteristics:

Fibre length: 4 m from LH to connector

NA: 0.085

Core geometric diameter: 8.5 µm Polarisation: SM, PM, nominal linear polarisation parallel to slow axes Termination: MIDI-AVIM connectors with 8 degree APC ends Fibre jacketing: Metal

I

LS.IF.OPT.015 LS optical fibre minimum bending radius The minimum bending radius of the LH to OBA and LH to FRS-O fibres shall be 45 mm.

I, T

LS.IF.OPT.090 Fibre polarisation angle The main optical output (LH.Req.Int.Opt.10) shall have the optical slow-axis of the fibre aligned to the connector key with an alignment accuracy of ±2 degrees.

T, A

5.3.2 Electrical Interfaces

LH.Req.Int.Elt.40 LH-PMS RF modulation interface

The LH shall accept from PMS an analogue signal in the form of a sine tone for phase modulation of the main optical carrier according to the following interface specification:

• Interface type: Analog single ended

• Impedance: 50 Ohm matched

• Coupling: AC

• Frequency: see LH.Req.Opt.113

• Spectral quality: Pure sine tone (TBC)

• Output power: -8 dBm to -4 dBm from PMS at input of laser after 5m PT150 cable

• Connector type: SMA

• Cable type: coax

• Redundancy: each LH shall accommodate two RF modulation interfaces, nominal and redundant cross-strapped to the PMS

I, T, R

LH.Req.Int.Elt.50 LH-PMS PRN modulation interface

The LH shall accept from PMS a digital data stream representing a PRN code with TBC Encoding and apply this signal unchanged to generate a direct sequence PRN phase modulation on the optical main carrier. The interface specification is as follows:

• Interface type: Analog differential signal, tuneable amplitude, 100 ohm source and termination

• Signal type: Direct sequence bitstream PRN code modulation

• Coding and error handling: Reed Solomon

• Coding specification: Balanced on subsequent blocks of 16 chips and no more than 5 identical sequential bits

• Chip rate: see LH.Req.Opt.120

• Symbol rate: < TBD

• Modulation scheme: BPSK

• PRN performance: see LH.Req.Opt.121 through LH.Req.Opt.125

• Connector type: Micro D 9S female (TBC) together with frequency control signals

• Cable type: Shielded twisted pair (TBC)

• Redundancy: each LH shall accommodate two PRN modulation interfaces, nominal and redundant cross-strapped to the PMS

I, T, R

LH.Req.Int.Elt.70 LH-PMS optical frequency control interface

The LH shall accept optical frequency control signals from PMS, according to the following interface specification:

• Interface Type: Analog differential

• Range: -2.5V to 2.5V for each individual line of the differential pair, such as when individual lines are combined the overall differential range is -5V to +5V. This range shall translate into optical frequency changes of at least 100 MHz via PZT, and 3.5 GHz via TEMP

• Bandwidth: PZT = 30 kHz (TBC). TEMP = 10 mHz

• Connector type: 1x Micro D 9S female containing PZT and TEMP signals

• Cable type: Shielded twisted pair

• Redundancy: none; a single set of fast/slow control signals per LH from PMS

I, T, R

LS.Req.Int.Elt.80 Slow and fast optical frequency actuator tuning coefficients maximum variability

The slow (TEMP) and fast (PZT) actuators of all LH shall have the following frequency tuning coefficients:

Slow actuator tuning coefficient (TEMP): 500 MHz/V ± 20% Fast actuator tuning coefficient (PZT): 14 MHz/V ±20%

R, T

LH.Req.Int.Elt.61 LH-PMON power control interface

The LH shall be connected to the PMON by an electrical harness which will be routed by Prime and IDS-OBA. The harness shall meet the following specification:

The minimum bending radius of the harness shall be 15 TBC mm The harness length shall be 5 m TBC The harness shall shall consist of the following:

• 1 m TBC harness from PMON to MOSA bracket with a TBD connector

• Connector feedthrough to be installed at MOSA bracket to be specified by provider and agreed to by ESA and Prime

• 4 m TBC harness from MOSA bracket to LH with a TBD connector

I, T, R

5.3.2.1 Power

LS.IF.BUS.00500 LS-SC power bus interface The LS-SC power bus interface is specifed as:

• Each LH shall provide a nominal and redundant interface to the SC power bus

R

LH.Req.Int.Elt.140 Power consumption: LH The power consumption of a single LH in any operational mode shall not exceed 145

W TBC.

A

5.3.2.2 Data and Timing

LS.IF.ELEC.030 LS-OBC TMTC interface Each LH shall provide a nominal and redundant TMTC interface to the OBC.

The OBC is responsible for commanding of the laser system.

I

LS.IF.ELEC.010 LS-OBC interface: TC

The LS shall accept, from the OBC, commands controlling the following functions:

• Mode changes

• Mode settings

• Switching between redundant sub-assemblies

• Control of set-points for frequency, power, temperature, etc.

R, T

LS.IF.ELEC.020 LS-OBC interface: TM The LS shall have a set of monitor telemetries whose aim will be to allow for LS operation, performance optimisation and problem diagnosis and resolution.

The TM shall be defined per operational mode as specified in LH.Req.Des.80 through LH.Req.Des.89.

R, T

LS.IF.ELEC.040 LS-OBC TMTC interface: SpaceWire The LS-OBC TMTC interface shall be SpaceWire and shall comply with the SpaceWire standard (ECSS-E-ST-50-12C) and CCSDS packet transfer protocol

(ECSS-E-ST-50-53C).

R

LS.IF.ELEC.050 LS-OBC TMTC interface: PUS-C The LS TMTC interface shall be PUS-C compatible.

I

LS.IF.ELEC.060 LS-OBC TMTC interface: maximum data rate The LS-OBC TMTC interface shall be compatible with a data rate of at least 10 Mbps.

R

LS.IF.ELEC.070 LS TM: maximum generation rate for downlink The LS maximum generation rate to be downlinked to ground shall be less than 10.5 kbps TBC (including all Payload Provider packet overheads and unit level margin).

T, A

LS.IF.ELEC.080 LS TM: maximum on board generation rate The LS maximum on board generation rate shall be less than 400 kbps TBC (including all unit level packet overheads and unit level margins).

T

LS.IF.ELEC.090 LS-OBC/CTU timing interface The LS-OBC/CTU timing interface is specifed as:

• Each LH shall provide a nominal and redundant interface to the OBC/CTU for USO and PPS signals

I

5.3.3 Mechanical Interfaces

LH.Req.IF.Mech.10 LH linear dimensions The LH, including connectors (both LH mounted and mating part) and mounting feet, shall fit inside the following linear dimensions:

x dimension: 350mm (TBC) y dimension: 255 mm (TBC) z dimension: 270 mm (TBC)

I, T

LH.Req.IF.Mech.15 LH Volume The LH volume shall not exceed 24 litres (TBC).

I, T

LH.Req.IF.Mech.17 LH connector location The LH connectors shall be mounted on the PY and PX faces.

I

5.3.4 Thermal interfaces

LH.Req.Env.Th.10 LH-SC conductive thermal interface

The LH to SC conductive interface is specfied as:

The LH shall have a smooth and planar baseplate to give full contact to the spacecraft for thermal control.

The local heat flux on the baseplate shall not be greater than 1.5 times the average heat flux.

The LH shall conduct at least 95% of it's power dissipation through the baseplate to the SC.

A

FRS.Req.IF.Th.40 LH-SC radiative thermal interface The LH shall radiate no more than 5% (TBC) of its power dissipation towards the SC.

A

5.3.5 PERFORMANCE I/F

5.3.5.1 TO SYS

LS.IF.SYS.00010

Maximum length constraint: LH-MOSA bracket optical fibre

The SC shall accommodate the LH such that the maximum length of the LH-MOSA bracket optical fibre (LH.Req.Int.Opt.10 ) is 4 m.

I

LS.IF.SYS.00015

Maximum length constraint: LH-FRS-O optical fibre

The SC shall accommodate the LS units such that the maximum length of the LH- FRS-O optical fibre is 5 m.

I

LS.IF.SYS.00016

Maximum length constraint: LH-FRS-E electrical harness

The SC shall accommodate the LS units such that the maximum length of the LH- FRS-E electrical harness is 5 m.

I

LS.IF.SYS.00019

Maximum length constraint: LH-PMON electrical harness

The SC shall accommodate the LS units such that the maximum length of the FRS-E- PMON electrical harness is 5 m TBC.

I

LS.IF.SYS.00017 LS electrical harness bending radius The LS electrical harness minimum bending radius shall be 20 mm.

I, T

LS.IF.SYS.00030 LH-FRS-O fibre thermal environment stability The SC shall ensure that LH-FRS-O optical harness experences thermal variations (see Figure 2) TBC.

A

LS.IF.BUS.00501 LH hard wired reset line The SC shall provide a direct reset line from OBC to LH LEM. The baseline is LVDS with LOW asserted to reset the LH. The reset line shall be redundant.

I

5.4 Design

LH.Req.Des.52 Laser System modularity: sub-system segregation All LS units i.e. LH, FRS-O, and FRS-E shall be completely separable from each other.

All LS units shall meet all requirements.

I

5.5 Environmental

5.5.1 Mechanical

LA.Req.Env.Mech.10 LH quasi-static load The LH shall withstand the following quasi-static design loads without degradation of performance:

• +/-20g in any direction

R, A, T

LA.Req.Env.Mech.20 LH random vibration level The LH shall withstand the following random vibration levels without degradation of performance (see Firgure 3 and Table 2).

R, A, T

LA.Req.Env.Mech.30 LH sine vibration level The LH shall withstand the following sinusoidal vibration levels without degradation of performance:

Note that no notching is expected to be applied (see Table 3).

R, A, T

LA.Req.Env.Mech.40 LH shock level The LH shall withstand the following shock levels without degradation of performance (see Figure 4).

R, A, T

5.5.2 Thermal

LH.Req.Env.Th.20 LH operational temperature range The LH shall meet the requirements for any temperature in the operating temperature range of 20 °C ± 5°C at its conductive and radiative boundaries.

A

LH.Req.Env.Th.30 LH operational environmental temperature stability The LH shall meet its requirements when the temperature stability at the conductive and radiative boundaries of its subsystem is at most 0.5*u_T (f) K/sqrt(Hz) TBC for frequencies within the measurement LISA measurement bandwidth.

R, A, T

LH.Req.Env.Th.33 LH-OBA optical fibre thermal environment stability The LS shall meet its performance requirements with a temperature noise of the LH- OBA optical fibre below (see Figure 1) TBC.

R, A, T

LH.Req.Env.Th.34 LH-FRS-O fibre thermal environment stability The LS shall meet its performance requirements with a temperature noise of the LH- FRS-O optical fibre below (see FIgure 2) TBC.

R, A

LH.Req.Env.Th.40 Power dissipation: LH The power dissipation of a single LH in any operational mode shall not exceed 145 W

TBC .

R, A

LH.Req.Env.Th.50 LH power dissipation fluctuations The power dissipation fluctuations of the LH shall be less than (TBC):

R, A, T

LH.Req.Env.Th.60 LH non-operative temperature range The LH non-operative design temperature range shall be -20 °C to +40°C.

T, A

LH.Req.Env.Th.70 LH storage and transportation temperature range The LH storage and transportation temperature range shall be -20 °C to +40°C. T, A

5.5.3 EMC

LH.Req.Env.El.0010 Laser Head magnetic moment allocation The magnetic moment of the Laser Head shall not exceed 125 (TBR) mAm^2. T, A

5.6 Verification

LH.Req.Ver.10 Performance verification The LS shall meets its requirements, and those requirements shall be verified by measurement, at the main optical output as specified in LH.Req.Int.Opt.10.

R

LH.Req.Ver.14 Ground test lifetime The LS design shall account for 12 months (TBC) of ground test lifetime.

A

LS.Req.Env.Gen.21 Performance at EOL LH pressure The LH shall be pressurized and filled with clean dry air. The LH shall demonstrate that the LS performance is met by test, considering the EOL LH pressure.

R, A, T

LS.ENV.VER.30

Performance over the operational temperature range

The LS provider shall demonstrate that the LS performance is met through test for a minimum of three points in the operating temperature range specified in LH.Req.Env.Th.20, LH.Req.Env.Th.21, LH.Req.Env.Th.22, LS.IF.OBA.00870. The testing baseline shall be at the mid point and extremes of the operating temperature ranges.

T

LH.Req.Ver.11 Verification approach: nominal test conditions Performance testing shall occur at the power specified in LS.PER.PWR.00010.

Note: the number of tested set-points and Fourier frequencies to be included in the performance testing require iteration and remain TBD.

T

5.7 Product assurance

LH.Req.Env.Gen.50 Cleanliness

The contamination on LS external surfaces shall not exceed at delivery the following level:

VC-0.5-1000-1500UV according to standard IEST-STD-CC1246E NOTE: The requirement is for cross-contamination purpose. The specification above means visually clean when inspected at a close distance with both white light and UV light.

I

LH.Req.Env.Gen.60 LIC derisking All non-metallic materials (e.g. glue) contained in the LS units housing must be submitted to a laser-induced contamination test to be defined by the LS provider.

Silicone glues must be avoided.

I

4×10&' @( * A ()⁄

Figures

Figure 1

Figure 2

Figure 3

Figure 4

Tables

Table 1

Table 2

Table 3