1. VIRGO_LCGT Meeting Laser & Mirror 5 November, 2010 Norikatsu Mio

2. Laser MC1 MC2 MC3 PRMPR1 PR2 BS SR2 SR1 SRM ITMX ITMY ETMX ETMY MT1 MT2 Schematic View of LCGT Optical System 780 W 75 W 150 W

3. EOM FI PD PZT Nd:YAG rod Nd:YAG NPRO quartz rotator 2W 100W BW FI QWP PBS WB-EOM Intensity stabilization （ Injection Current Control ） 150W Frequency Stabilization f < 10 kHz PZT, Crystal Temp. 10 kHz < f < 1 MHz WB-EOM Injection Locked laser Master: 2-W NPRO Slave: Mitsubishi Power Amplifier High-Power Laser Modules Mitsubishi Laser for LCGT

4. Laser Basic design has been tested with a prototype laser. Discussion with Mitsubishi that makes laser modules for LCGT. – We will buy laser modules from Mitsubishi and assemble a laser system from them by ourselves or by another company. Alternative choice? – Commercial fiber laser: 40W

6. Alternative design Mitsubishi laser modules Fiber laser amplifiers NPRO(500mW) 40 W 80 W 200 W

7. Laser MC1 MC2 MC3 PRM PR1 PR2 BS SR2 SR1 SRM ITMX ITMY ETMX ETMY MT1 MT2 Size of these mirrors must be determined according to the design policy of the interferometer.  38cm  10cm Mirrors for LCGT Mirrors for Main cavities Initial: Silica Final: Sapphire

8. Mirror Size of the mirrors for main cavities was determined as  25cm x t10cm in order to make full use of the iLIGO mirror substrates. Size of the beam splitter is  38cm x t12cm. The substrate will be prepared within this year. Concerning polishing and coating, several companies inquired the situations. We need to develop a new coating machine for large mirrors. Some Japanese companies may collaborate with us; this issue is under consideration. Polish: Collaboration with Riken Group – Details are not fixed.

9. Current Plan For iLCGT, the size of the mirrors is chosen as that of iLIGO’s mirror. BS and ITMs will be newly fabricated from Japanese Silica.

10. Sapphire We need a C-axis mirror(  25cm x t15cm). Reply from GT Crystal systems – Current Max size of C-axis mirror:  20cm x t15cm A-Plane mirror:  25cm x t15cm “With time we feel can develop larger C-axis sapphire slabs to achieve your goal of 25cm x 15cm sapphire mirrors with our HEM growth process.” Inquiring – when we can obtain C-axis mirror of  20cm x t15cm? – price and delivery time of max size of C-axis mirror(  20cm x t15cm) and A-Plane mirror (  25cm x t15cm). – No answer (the quotations will be made in this week!).

11. appendix

12. Laser module （ Mitsubishi ） Two rods and rotator Diffusive reflector +LD