1. Method for transferringreceiving audio andor video signals fulfilling the requirement to bridge synchronous and asynchronous networks and minimizing delay time over such networks comprising:
analysing an active network interface or verifying which network interface is receiving andor sending data;
taking a synchronous-clock signal from the network and providing said synchronous-clock signal to a bitstream analyser;
analysing a format of a multiplexed signal obtained from an audio codec;
analysing an audio format;
adapting an ISDN network clock to an IP network clock, and resulting in a clock-adapted digital signal;
encoding said clock-adapted digital signal;
adapting the encoded clock-adapted digital signal to IP datagrams as required by the network interface and by the active network itself in terms of protocols and packet size, resulting in a datagram signal; and
taking the datagram signal and putting the datagram signal in an IP network.
2. Method for transferringreceiving audio andor video signals fulfilling the requirement to bridge synchronous and asynchronous networks according to claim 1, wherein a data inserter is used to insert additional data, either within the encoded signal or in a separated stream, or, alternatively, used to replace less significant bits of the encoded signal with such additional data.
3. Apparatus for transferring audio andor video signals fulfilling the requirement to bridge synchronous and asynchronous networks comprising
means for analysing an active network interface or verifying which network interface is receiving andor sending data;
means for taking a synchronous-clock signal from the network and providing the synchronous-clock signal to a bitstream analyser;
means for analysing a format of a multiplexed signal obtained from an audio codec;
means for analysing an audio format;
means for adapting an ISDN network clock to an IP network clock and resulting in a clock-adapted digital signal;
means for encoding said clock-adapted digital signal;
means for adapting the encoded clock-adapted digital signal to IP datagrams as required by the active network interface and by the network itself in terms of protocols and packet size, and resulting in a datagram signal; and
means for taking the datagram signal and putting the datagram signal in an IP network.
4. Apparatus for receiving audio andor video signals fulfilling the requirement to bridge synchronous and asynchronous networks for the reception of audio andor video signals and minimizing delay time over Internet networks comprising
means for analysing an active network interface or verifying which network interface is receiving andor sending data;
means for taking a synchronous-clock signal from a network and providing said synchronous-clock signal to a bitstream analyser.
means for analysing a format of a multiplexed signal obtained from an audio codec;
means for analysing an audio format;
means for adapting an ISDN network clock to an IP network clock and resulting in a clock-adapted digital signal;
means for encoding said clock-adapted digital signal;
means for adapting the encoded clock-adapted digital signal to IP datagrams as required by the active network interface and by the network itself in terms of protocols and packet size, and resulting in a datagram signal; and
means for taking the datagram signal and putting the datagram signal in an IP network.
5. System for transferringreceiving audio andor video signals fulfilling the requirement to bridge synchronous and asynchronous networks for transferringreceiving audio andor video signals and minimizing delay time over Internet networks comprising
means for analysing an active network interface or verifying which network interface is receiving andor sending data;
means for taking a synchronous-clock signal from a network and providing said synchronous-clock signal to a bitstream analyser;
means for analysing a format of a multiplexed signal obtained from an audio codec;
means for analysing an audio format;
means for adapting an ISDN network clock to an IP network clock and resulting in a clock-adapted digital signal;
means for encoding said clock-adapted digital signal;
means for adapting the encoded clock-adapted digital signal to IP datagrams as required by the active network interface and by the network itself in terms of protocols and packet size, and resulting in a datagram signal; and
means for taking the datagram signal and putting the datagram signal in an IP network.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system comprising:
first and second sources configured to emit corresponding first and second beams of radiation;
a beam selection device comprising a tiltable mirror configured to be tiltable about two axes, wherein:
the tiltable mirror is positioned such that the first beam of radiation is incident on the tiltable mirror at a first angle of incidence and the second beam is incident on the tiltable mirror at a second angle of incidence, and
the beam selection device is configured to select one of the first and second beams of radiation as a measurement beam of radiation by tilting the tiltable mirror;
an objective lens configured to direct the measurement beam of radiation onto the target on the substrate and to collect radiation diffracted by the target; and
a sensor configured to detect an angle resolved spectrum in a pupil plane of the objective lens.
2. The system of claim 1, wherein the first beam of radiation differs from the second beam of radiation in spot size or angular distribution.
3. The system of claim 1, further comprising an aperture plate having first and second openings configured to pass the first and second beams of radiation, respectively.
4. The system of claim 3, wherein:
the tiltable mirror is positioned in a conjugate plane of the substrate, and
the aperture plate is positioned in a plane that is a Fourier transform of the conjugate plane of the substrate.
5. The system of claim 1, wherein the first source comprises:
a broadband radiation source configured to emit a third beam of radiation having a first wavelength range; and
a wavelength selection device configured to output the first beam of radiation by selecting a second wavelength range from the third beam of radiation.
6. The system of claim 5, wherein the wavelength selection device comprises an acousto-optical tunable filter, a dispersive element, or an interference filter.
7. The system of claim 5, wherein the broadband radiation source comprises a supercontinuum laser.
8. The system of claim 1, wherein at least one of the first and second sources comprises a xenon lamp.
9. The system of claim 1, wherein:
the first source comprises a xenon lamp; and
the second source comprises:
a broadband radiation source configured to emit a third beam of radiation having a first wavelength range; and
a wavelength selection device configured to generate the second beam of radiation by selecting a second wavelength range from the third beam of radiation.
10. The system of claim 9, wherein the wavelength selection device comprises an acousto-optical tunable filter, a dispersive element or an interference filter.
11. The system of claim 9, wherein the broadband radiation source comprises a supercontinuum laser.
12. The system of claim 1, wherein each of the first and second sources comprises a xenon lamp.
13. The system of claim 1, wherein:
the objective lens has a pupil plane;
the first and second sources are configured so that the first and second beams of radiation have respective spatial extents and angular ranges at a plane conjugate with the pupil plane of the objective lens; and
at least one of the spatial extent and angular range of the first illumination beam being different from the spatial extent and angular range of the second illumination beam.
14. The system of claim 1, wherein:
the beam selection device further comprises an optical system configured to direct the first and second beams of radiation onto a pivot point of the tiltable mirror, and
the optical system comprises the aperture plate.
15. The system of claim 1, wherein the tiltable mirror is configured so that changes in its orientation change the angle of incidence of the measurement beam of radiation on the substrate.
16. The system of claim 1, wherein the beam selection device further comprises a selectable aperture stop.
17. The apparatus according claim 1, further comprising:
an additional sensor;
a beam splitter configured to direct a part of the radiation collected by the objective lens to the additional sensor; and
an imaging optical system configured to form an image of the target on the additional sensor.
18. A system comprising:
an illumination optical system arranged to illuminate a pattern;
a projection optical system arranged to project an image of the pattern onto a substrate; and
a metrology device configured to measure a property of a target on the substrate, the metrology device comprising:
a first source configured to emit a first beam of radiation;
a second source configured to emit a second beam of radiation;
a beam selection device comprising a tiltable mirror configured to be tiltable about two axes, wherein the tiltable mirror is positioned such that the first beam of radiation is incident on the tiltable mirror at a first angle of incidence and the second illumination beam is incident on the tiltable mirror at a second angle of incidence and wherein the beam selection device is configured to select one of the first and second illumination beams of radiation as a measurement beam of radiation by tilting the tiltable mirror;
an objective lens configured to direct the measurement beam of radiation onto the target on the substrate and to collect radiation diffracted by the target; and
a sensor configured to detect an angle resolved spectrum in a pupil plane of the objective lens.
19. The system of claim 18, further comprising:
an exposure station; and
a measurement station,
wherein the substrate table is moveable between the exposure station and the measurement station, and
wherein the metrology device is positioned at the measurement station.
20. A method of measuring a property of a target on a substrate, the method comprising:
generating first and second illumination beams, the first and second illumination beams differing in at least one of spatial extent and range of angles, the first and second beams being incident on a mirror configured to be tiltable about two axes, wherein the first beam of radiation is incident on the mirror at a first angle of incidence and the second illumination beam is incident on the mirror at a second angle of incidence;
tilting the mirror such that one of the first and second illumination beams is directed onto the target;
collecting radiation diffracted from the target using an objective lens; and
detecting an angle-resolved spectrum in a pupil plane of the objective lens.