1. An apparatus comprising:
a pulsed gas discharge laser lithography light source comprising:
a seed laser portion providing a seed laser output light beam of seed pulses;
an amplifier portion receiving the seed laser output light beam and amplifying the optical intensity of each seed pulse to provide a high power laser system output light beam of output pulses;
a pulse stretcher increasing the number of peaks in the output pulse and decreasing the average peak intensity of each of the output pulses by passing the output pulses through a pair of optical delay paths in series;
the pulse stretcher comprising:
a first beam splitter operatively connected with the first delay path and a second pulse stretcher operatively connected with the second delay path;
a first optical delay path tower containing the first beam splitter;
a second optical delay path tower containing the second beam splitter;
one of the first and second optical delay paths comprising:
a plurality of mirrors defining the respective optical delay path including mirrors located in the first tower and in the second tower;
the other of the first and second optical delay paths comprising:
a plurality of mirrors defining the respective optical delay path including mirrors only in one of the first tower and the second tower.
2. The apparatus of claim 1 further comprising:
the first optical delay path and the second optical delay path being of unequal length.
3. The apparatus of claim 1 further comprising:
the first optical delay path being longer than the second optical delay path.
4. The apparatus of claim 2 further comprising:
the one of the first and second optical delay towers containing mirrors in both of the first and second towers being the longer of the first and second optical delay paths.
5. The apparatus of claim 3 further comprising:
the one of the first and second optical delay towers containing mirrors in both of the first and second towers being the longer of the first and second optical delay paths.
6. The apparatus of claim 4 further comprising:
the longer of the first and second optical delay paths being the first optical delay path.
7. The apparatus of claim 1 further comprising:
the mirrors comprising imaging mirrors.
8. The apparatus of claim 6 further comprising:
the mirrors comprising imaging mirrors.
9. The apparatus of claim 1 further comprising:
the mirrors comprising confocal mirrors.
10. The apparatus of claim 6 further comprising:
the mirrors comprising confocal mirrors.
11. The apparatus of claim 8 further comprising:
the mirrors comprising confocal mirrors.
12. An apparatus comprising:
a pulsed gas discharge laser lithography light source comprising:
a seed laser portion providing a seed laser output light beam of seed pulses;
an amplifier portion receiving the seed laser output light beam and amplifying the optical intensity of each seed pulse to provide a high power laser system output light beam of output pulses;
the amplifier portion comprising a ring power amplifier comprising amplifier portion injection optics comprising at least one beam expanding prism, a beam reverser and an inputoutput coupler;
the beam expansion optics and the output coupler being mounted on an optics assembly with the beam expansion optics rigidly mounted with respect to the optics assembly and the inputoutput coupler mounted for relative movement with respect to the optics assembly for optical alignment purposes.
13. The apparatus of claim 12 further comprising:
the inputoutput coupler being mounted for movement with respect to the optic assembly in a first axis and a second axis.
14. The apparatus of claim 13 further comprising:
the first axis and second axis being generally orthogonal to each other.
15. The apparatus of claim 12 further comprising:
the amplifier injection optics being contained within an amplifier portion injection optics assembly box and the inputoutput coupler comprising at least one through-the-wall adjusting actuator to adjust the position of the inputoutput coupler in at least one axis.
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 self-service terminal comprising:
a fascia;
a transmitter sending a chirped ultrasonic pulse across a region of the fascia;
wherein the pulse interacts with the region;
a receiver receiving the pulse after the pulse has interacted with the region and produces an electrical output corresponding to the received pulse; and,
an analysing module converting the electrical output to a frequency domain, the analyzing module comparing the frequesncy domain converted electrical output to a baseline frequency response.
2. A self-service terminal according to claim 1, where the frequencies of the pulse are in the range of 30 to 100 KHz.
3. A self-service terminal according to claim 1, wherein the region comprises one or more parts of the fascia.
4. A self-service terminal according to claim 1, further comprising a signal generator producing a chirped electrical pulse that the transmitter converts into a chirped ultrasonic pulse.
5. A self-service terminal according to claim 1, further comprising a microprocessor controlling the signal generator and analysing module.
6. A self-service terminal according to claim 1, further comprising a memory storing the baseline frequency response andor frequency response characterisations.
7. A self-service terminal according to claim 1, wherein the transmitter sends a succession of pulses.
8. A self-service terminal according to claim 1, wherein the pulse is damped.
9. A self-service terminal according to claim 1, wherein the transmitter and receiver are co-located.
10. A self-service terminal according to claim 1, wherein the transmitter and receiver are combined as a single transducer unit.
11. A method of detecting foreign bodies at a self-service terminal, the method comprising:
sending a chirped ultrasonic pulse across a region of a fascia of the terminal so that the pulse interacts with the region, wherein the region is associated with a magnetic card slot of the self- service terminal;
receiving the pulse after the pulse has interacted with the region;
producing an electrical output corresponding to the received pulse; and,
analysing the electrical output by converting the electrical output to a frequency domain and comparing the frequency domain converted electrical output to a baseline frequency response.
12. A method according to claim 11, further comprising determining the baseline frequency response in the absence of foreign bodies and subsequently comparing a determined frequency response with the baseline frequency response.
13. A method according to claim 12 wherein a succession of chirped pulses are sent across the fascia and the baseline frequency response is established on the basis of a historical average of frequency responses.
14. A method according to claim 12, further comprising characterising a range of foreign bodies by determining a frequency response with each foreign body present, storing the frequency responses and subsequently comparing a determined frequency response with the stored frequency responses.
15. A method according to claim 11 wherein analysing the electrical output also, or instead of making the frequency domain analysis, includes making a time domain analysis of the electrical output.