I don't know if this is a good idea with optics but other parts i use a steam cleaner, that generally works out very well, even if it's rum and coke spilled into a power supply, but it seems to work well for pcb and other stuff, optics you would get water inside and cause major fogging. steam and a clean brush do work wonders with no solvents
Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu