Ion mirror and ion-optical lens for imaging

An ion mirror comprising:

• an ion entrance electrode section at the ion entrance to the ion mirror;
• an energy focussing electrode section for reflecting ions back along a longitudinal axis towards said ion entrance;
• a spatial focussing electrode section arranged between the ion entrance electrode section and the energy focussing electrode section for spatially focussing the ions;
• one or more DC voltage supply configured to apply different DC voltages to the ion entrance electrode section, the spatial focussing electrode section and the energy focussing electrode section, and to apply a DC potential to the spatial focussing electrode section that is intermediate the DC potential applied to the ion entrance electrode section and a DC potential applied to the energy focussing electrode section;
• and
• wherein at least one first transition electrode is arranged between said ion entrance electrode section and said spatial focussing electrode section, wherein said one or more DC voltage supply is configured to apply a DC potential to said at least one first transition electrode that is intermediate the DC potential applied to the ion entrance electrode section and the DC potential applied to the spatial focussing electrode section;
• and
• wherein at least one second transition electrode is arranged between said energy focussing electrode section and said spatial focussing electrode section, wherein said one or more DC voltage supply is configured to apply a DC potential to said at least one second transition electrode that is below the DC potential applied to the spatial focussing electrode section.

A time of flight mass spectrometer comprising:

• a time of flight region for separating ions according to their mass to charge ratio;
• and
• an ion optical lens for spatially focussing ions arranged within the time of flight region, said lens comprising:
• an ion entrance electrode section and an ion exit electrode section at opposite ends of the lens, and a spatial focussing electrode section arranged between the ion entrance and ion exit electrode sections for spatially focussing ions passing through the lens;
• one or more DC voltage supply configured to apply DC voltages to the ion entrance electrode section, the spatial focussing electrode section and the ion exit electrode section;
• and to apply a DC potential to the spatial focussing electrode section that is either lower or greater than both the DC potential applied to the ion entrance electrode section and the DC potential applied to the ion exit electrode section;
• at least one first transition electrode arranged between said ion entrance electrode section and said spatial focussing electrode section, wherein said one or more DC voltage supply is configured to apply a DC potential to said at least one first transition electrode that is intermediate the DC potential applied to the ion entrance electrode section and the DC potential applied to the spatial focussing electrode section;
• and
• at least one second transition electrode arranged between said ion exit electrode section and said spatial focussing electrode section, wherein said one or more DC voltage supply is configured to apply a DC potential to said at least one second transition electrode that is intermediate the DC potential applied to the ion exit electrode section and the DC potential applied to the spatial focussing electrode section.