Method of measuring chlorophyll fluorescence

A method of measuring chlorophyll fluorescence, the method comprising:

• performing a first chlorophyll fluorescence measurement at one or more different areas of a crop, wherein performing each first chlorophyll fluorescence measurement comprises
• using an actuator configured to controllably direct the light from a light source and aiming said light source at an area of the crop,
• using the light source to emit substantially collimated or convergently focused light so as to irradiate the area with light;
• using an optical sensor, detecting chlorophyll fluorescence from the area, and
• using a controller, recording the location of the area;
• and then performing a second chlorophyll fluorescence measurement at the one or more different areas, wherein performing each second chlorophyll fluorescence measurement comprises
• using the actuator, aiming said light source at one of said areas based on the recorded location of the area in the respective first chlorophyll fluorescence measurement,
• using the light source to emit substantially collimated or convergently focused light so as to irradiate the area with light, and
• using the optical sensor, detecting chlorophyll fluorescence from the area, and
• wherein a) performing each first chlorophyll fluorescence measurement comprises selecting an area to aim the light source at based on one or more captured images of the crop, and/or b) recording the location of the area for each first chlorophyll fluorescence measurement comprises saving a captured image of the area, and aiming the light source at one of the areas for each second chlorophyll fluorescence measurement comprises capturing an image of the crop, comparing the captured image of the crop with the saved captured image of the area from the first chlorophyll fluorescence measurement, and adjusting the aim of the light source based on the result of the comparison.

A method of measuring chlorophyll fluorescence, the method comprising:

• performing a first chlorophyll fluorescence measurement at one or more different areas of a crop, wherein performing each first chlorophyll fluorescence measurement comprises
• using an actuator configured to controllably direct the light from a light source and aiming said light source at an area of the crop,
• using the light source to emit substantially collimated or convergently focused light so as to irradiate the area with light;
• using an optical sensor, detecting chlorophyll fluorescence from the area, and
• using a controller, recording the location of the area;
• and then performing a second chlorophyll fluorescence measurement at the one or more different areas, wherein performing each second chlorophyll fluorescence measurement comprises
• using the actuator, aiming said light source at one of said areas based on the recorded location of the area in the respective first chlorophyll fluorescence measurement,
• using the light source to emit substantially collimated or convergently focused light so as to irradiate the area with light, and
• using the optical sensor, detecting chlorophyll fluorescence from the area, wherein each first chlorophyll measurement is performed while the crop is in one of a dark-adapted state or a light-adapted state, and wherein each second chlorophyll measurement is performed while the crop is in the other of a dark-adapted state or a light-adapted state.