Vertical motion axis for imaging optical head

A system comprising:

• a first plate;
• a second plate, wherein the second plate is moveable with respect to the first plate along a vertical direction associated with a weight of the second plate, wherein the second plate is configured to connect to one or more objects;
• one or more magnetic counterbalances coupled to the first and second plates and providing a counterbalance force to the second plate in the vertical direction opposing the weight of the second plate, wherein at least one of the one or more magnetic counterbalances comprises a tunable magnetic counterbalance, wherein the tunable magnetic counterbalance comprises:
• a first portion including a rod including one or more magnets, the first portion attached to one of the first plate or the second plate;
• and
• a second portion including a ferromagnetic sleeve formed from one or more ferromagnetic materials and at least partially surrounding the one or more magnets of the rod, the second portion attached to a different one of the first plate or the second plate than the first portion, wherein the one or more ferromagnetic materials of the ferromagnetic sleeve at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction, wherein the first and second portions are separated by a gap, wherein the counterbalance force is adjustable by controlling at least one of a relative rotation angle between the first and second portions in the horizontal plane or a length of the gap along at least one direction, wherein the ferromagnetic sleeve includes a slit configured to weaken magnetic field flow;
• a motorized actuator mechanically coupled to at least one of the first portion or the second portion and configured to adjust the relative rotation angle between the first and second portions in the horizontal plane, wherein the actuator is configured to automatically tune the counterbalance force;
• a translation stage for positioning a sample in at least the horizontal plane;
• an actuator configured to position the second plate with respect to the first plate along the vertical direction;
• an encoder, wherein the encoder is configured to measure a relative position of the second plate;
• and
• a controller communicatively coupled to the tunable magnetic counterbalance, the controller including one or more processors configured to execute program instructions causing the one or more processors to:
• receive a relative position of the second plate;
• and
• provide feedback to the motorized actuator and the actuator via one or more drive signals.

A method comprising:

• placing a sample at a selected distance in a vertical direction from one of one or more objects, wherein the object is connected to a translation stage, wherein the translation stage comprises:
• a first plate;
• a second plate, wherein the second plate is moveable with respect to the first plate along the vertical direction, wherein the vertical direction is associated with a weight of the second plate, wherein the one or more objects are connected to the second plate;
• one or more magnetic counterbalances coupled to the first and second plates and providing a counterbalance force to the second plate in the vertical direction opposing the weight of the second plate, wherein at least one of the one or more magnetic counterbalances comprises a tunable magnetic counterbalance, wherein the tunable magnetic counterbalance comprises:
• a first portion including a rod including one or more magnets, the first portion attached to one of the first plate or the second plate;
• and
• a second portion including a ferromagnetic sleeve formed from one or more ferromagnetic materials and at least partially surrounding the one or more magnets of the rod, the second portion attached to a different one of the first plate or the second plate than the first portion, wherein the one or more ferromagnetic materials of the ferromagnetic sleeve at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction, wherein the first and second portions are separated by a gap, wherein the counterbalance force is adjustable by controlling at least one of a relative rotation angle between the first and second portions in the horizontal plane or a size of the gap along at least one direction wherein the ferromagnetic sleeve includes a slit configured to weaken magnetic field flow;
• a motorized actuator mechanically coupled to at least one of the first portion or the second portion and configured to adjust the relative rotation angle between the first and second portions in the horizontal plane, wherein the actuator is operatively connected to a controller configured to execute program instructions to automatically tune the counterbalance force;
• and
• an actuator configured to position the second plate with respect to the first plate along the vertical direction;
• and
• an encoder, wherein the encoder is configured to measure a relative position of the second plate and provide feedback to the actuator;
• adjusting the counterbalance force to be equal to a combined weight of the second plate and the one or more objects;
• generating measurements of at least one of position of the sample along the vertical direction or a distance in the vertical direction between the sample and the at least one of the one or more objects on the second plate;
• and
• maintaining, via the actuator, the selected distance in the vertical direction between the sample and the one of one or more objects based on the measurements.