摘要 |
A radiation source suitable for providing a beam of radiation to an illuminator of a lithographic apparatus. The radiation source comprises a nozzle configured to direct a stream of fuel droplets along a trajectory towards a plasma formation location. The radiation source is configured to receive a first amount of radiation such that, in use, the first amount of radiation is incident on a fuel droplet at the plasma formation location. The first amount of radiation transfers energy to the fuel droplet to generate a radiation generating plasma that emits a second amount of radiation. The radiation source further comprises an alignment detector having a first sensor arrangement and a second sensor arrangement. The first sensor arrangement is configured to measure a property of a third amount of radiation that is indicative of a focus position of the first amount of radiation. The second sensor arrangement is configured to measure a property of a fourth amount of radiation, the fourth amount of radiation being a portion of the first amount of radiation that is reflected by the fuel droplet upon which the first amount of radiation is incident. |