| 摘要 |
PURPOSE: To reduce an offset signal difficult to remove heretofore while enhancing an S/N ratio. CONSTITUTION: In an infrared gas analyser constituted so that the synchronizing signal (s) based on the rotary cycle of an optical chopper 6 is appropriately shifted in phase by a phase-shifting circuit 16 and detector output (a) is synchronously rectified by the phase shifted synchronizing signal (s), a second phase- shifting circuit 17 capable of shifting the synchronizing signal (s) by 90 deg. and the circuit 18 bypassing the same are provided in the signal line 15 of the synchronizing signal in parallel. The second phase-shifting circuit 17 and the bypass circuit 18 are alternately connected to adjust the phase shift of the synchronizing signal (s) to cancel the offset quantity caused by the axial shift of the optical chopper 6. |
