As you see, if FLASH1 STROBE be 4.8 volts, voltage of
collector will be 0.18 volt. FLASH1 STROBE comes from a ATMEGA16 port. Is there any problem with this design? I mean 0.18 volt on collector and 4.8 volt on FLASH1 STROBE.
There are two problems normally optoisolators in this setup: - Rise times - Not a low enough V_IL for the gate driver
Rise times aren't going to be a problem at 5 to 10Hz. The V_IL is 0.8V for the TC4426 so if the optoisolator pulls down to 0.2V you should be fine.