MIF Task List
- MIF Task List
LSC ASC Overall Design (Aso, Michimura, (Nakano ?))
Green Lock System (Tatsumi, Ueda)
RTS code implementation (Miyakawa)
Commissioning Planning (Aso)
Vacuum Enclosure & Wiring for In-Vac PDs (Akutsu, Yamamoto)
PD Protection Shutter (Somiya, Akutsu)
Output Mode Cleaner (Somiya, Michimura, Arai)
LSC ASC Overall Design
- Design the signal sensing scheme for LSC/ASC
- Design the overall servo topology of LSC/ASC
- Design the servo filters for LSC/ASC
Frequency Stabilization Servo
The frequency stabilization servo (FSS) is a multi-loop servo system to ultimately stabilize the laser frequency. There are three references used to hierarchically stabilize the laser frequency. The most inner reference is the reference cavity, which serves as the frequency reference at DC. The MC is the second loop, which is ultimately taken over by the CARM loop. Since the FSS loops are high BW, the feedback filters are mostly implemented in analog. Only the part of signals fed back to the mirrors of the MC and ETMs are processed by the digital RTS. The slow thermal control of the laser frequency will also be performed digitally.
- Make a conceptual design of the overall system.
- Calculate requirements (BW, noise) to the components in the servo.
- Design the analog filter circuits.
- Borrow as much as possible from aLIGO design, as usual.
Green Lock System
We should work in collaboration with the IOO group on the practical implementation of the green lock system. Task List:
- Fix the overall design of the green lock system.
- Design practical optical system
- Design necessary analog electronics
RTS code implementation
Implement servo systems with realtime system codes.
- Make RTS models of LSC and ASC systems
- Create MEDM screens
- Create appropriate filters
- Write necessary scripts to lock and adjusts the interferometer
- Simulated plant for above tasks
- Devise the procedures for commissioning
- Man power management
Electronics Circuit Design
Design and manufacturing of necessary electronics circuits for interferometer control.
The tasks include:
- Schematic design (mostly borrow designs from aLIGO)
- PCB design (mostly borrow designs from aLIGO)
- Work with the Analog Electronics Group to manufacture, test, install the circuits
Here is an incomplete list of circuits
- RF PD
- RF QPD
- DC PD for DC readout
- DC PD for Intensity Monitor
- DC QPD
- I-Q demodulator
- LO Distribution
- Whitening Filter
- Variable Gain Amp
- FSS Servo Circuits
- Green Lock Circuits
Vacuum Enclosure & Wiring for In-Vac PDs
Some of the core PDs and QPDs have to be placed inside the vacuum. Those PDs will be put in hermetic enclosures. The wires used to communicate with those PDs have to be also vacuum compatible.
The tasks are:
- Design the airtight enclosures
- Make sure that the heat can escape from the PD.
- Chose appropriate (vacuum compatible) wires for signal and power transmission.
PD Protection Shutter
All the PDs have to be protected against sudden increase of the incident power, for example when the lock is lost. A quick mechanism to deflect the beam path from the PDs is necessary.
The tasks are:
- Calculate the requirements (speed, power, etc).
- Investigate the PD protection mechanisms employed by other groups (aLIGO, aVirgo).
- See if we can borrow those designs.
- If so, adopt the design to KAGRA.
- If not, develop our own design.
Beam handling during All-In-Vac operation
During the science mode, we want to operate solely on the PDs inside the vacuum. There will be no light coming out to the air at all. The main reason for this is to avoid scattering light problems (things in the air vibrate much more at audio frequencies due to accoustic noise). However, this configuration poses some challenges to us.
First of all, all the light power has to be somehow dissipated in the vacuum. Even though the detection chambers (in which the PDs are installed) are at room temperature, we have to make sure that the heat is properly disposed. If the temperature of the PDs change too much during a lock, we may have slow drift problems.
Secondly, beams from the interferometer are extracted out to the air and detected by large range (but more noisy) PDs for lock acquisition. Once the interferometer is locked, we have to close those windows. Just closing the lid is not enough because the lid will generate a heck of scattered light. We have to come up with a way to gracefully shut down the beam going out to the air. Moreover, just damping the beam is not enough at some detection ports. In order to maximize the light power going to the in-vac PDs (to minimize the shot noise), we may want to change the power ratio between the in-air and the in-vac PDs after the lock acquisition. We probably send more power to the air during the lock acquisition, while we want send most of the light to the in-vac PDs after the lock.
- Develop a way to remotely close the optical window without generating scattered light.
- Develop a way to remotely change the power ratio between the beam going to the air and the in-vac PDs.
Output Mode Cleaner
Design, fabrication and commissioning of the Output Mode Cleaner.
- Finalize the conceptual design
- Design the control scheme
- Mechanical Design
- Prototype Test
- Fabrication and commissioning of the final OMC.