Optical system, optical delay line and OCT apparatus
An optical system, capable to admit a light beam, the optical system comprising: a plurality of reflectors configured to reflect the light beam, wherein each of the reflectors is configured to reflect an incident light beam such that the path of the incident light beam and the path of the reflected light beam are parallel to each other. Each of the reflectors has a reflection center axis positioned centrally between the path of the incident light beam and the path of the reflected light beam. At least two of the reflectors are arranged relative to each other such that their respective reflection center axes do not overlap, thereby enabling the path of the light beam to pass at least one of the at least two of the reflectors multiple times.
1. An optical system, capable to admit a light beam, the optical system comprising:
a plurality of reflectors comprising a first reflector and a second reflector, the plurality of reflectors being configured to reflect the light beam wherein:
each of the reflectors is configured to reflect an incident light beam according to a number of passes, such that, for each pass of the number of passes, a path of the incident light beam and a path of the reflected light beam are parallel to each other;
each of the reflectors has a reflector center axis positioned centrally between the path of the incident light beam and the path of the reflected light beam; and
the first reflector and the second reflector are arranged relative to each other such that their respective reflector center axes do not overlap, thereby enabling the path of the light beam to pass at least one of the first reflector or the second reflector multiple times; and
in operation of the optical system:
the light beam reflected from the first reflector is incident on the second reflector and reflected by the second reflector back to the first reflector;
the light beam is incident on the first reflector first, before being incident on any other of the reflectors;
the light beam is last reflected by the first reflector such that, after the last reflection from the first reflector, the light beam is not incident on any other of the reflectors; and
at least one of the first reflector or the second reflector is movable in an adjustment direction that is orthogonal to its respective reflector center axis, thereby changing the number of passes in which incident light and reflected light are parallel, to permit a length of the light beam between the first reflector and the second reflector to be adjusted in discrete steps according to the changed number of passes.
2. The optical system of claim 1 , further comprising a specular element configured to reflect the light beam such that at least one of a path of the light beam reflected by the specular element or a path of the light beam incident on the specular element is not parallel to a path of the light beam incident to any one of the reflectors.
3. The optical system of claim 1 , wherein at least one of the path of the first light beam incident on the first reflector, or the path of the last light beam reflected by the first reflector, is not incident on the second reflector.
4. The optical system of claim 1 , wherein each of the reflectors comprises a respective one of:
a mirror arrangement comprising two orthogonal mirrors;
a corner cube comprising three orthogonal mirrors;
a corner cube prism; or
a Luneburg lens.
5. The optical system of claim 1 , wherein at least one of the reflectors is configured so as to be movable in an adjustment direction, the adjustment direction being parallel to the reflector center axis of the at least one reflector.
6. The optical system of claim 1 , further comprising a light source configured to provide the light beam.
7. The optical system of claim 1 , wherein the optical system further comprises at least one of a light input device or a light output device, and wherein, in operation of the optical system, at least one of:
the path of the light beam first incident on the first reflector emerges from the light input device; or
the path of the light beam last reflected by the first reflector is incident on the light output device.
8. The optical system of claim 7 , wherein the light input device comprises an input fibre collimator.
9. The optical system of claim 7 , wherein the light output device comprises an output fibre collimator.
10. The optical system of claim 1 , wherein at least one of the reflectors is provided with at least one reflecting surface and at least one light beam passage said light beam passage being located on the at least one reflecting surface and being configured to allow transmission of the light beam therethrough.
11. The optical system of claim 10 , wherein, in operation of the optical system, at least one of the path of the light beam first incident on the first reflector or the path of the light beam last reflected by the first reflector, passes through the at least one light beam passage.
12. The optical system of claim 1 , wherein:
each of the reflectors has a projected area, said projected area being defined as a two-dimensional projection of the respective reflector in a direction of a respective reflector center axis, and
the projected area of each of the reflectors at least partially overlaps with the projected area of at least one other of the reflectors.
13. The optical system of claim 12 , wherein the reflector center axis of at least one of the reflectors intersects the projected area of at least one other of the reflectors.
14. An optical delay line for an optical coherence tomography apparatus, the optical delay line comprising an optical system capable to admit a light beam, the optical system comprising:
a plurality of reflectors comprising a first reflector and a second reflector, the plurality of reflectors being configured to reflect the light beam, wherein:
each of the reflectors is configured to reflect an incident light beam according to a number of passes, such that, for each pass of the number of passes, a path of the incident light beam and a path of the reflected light beam are parallel to each other;
each of the reflectors has a reflector center axis positioned centrally between the path of the incident light beam and the path of the reflected light beam; and
the first reflector and the second reflector are arranged relative to each other such that their respective reflector center axes do not overlap, thereby enabling the path of the light beam to pass at least one of the first reflector or the second reflector multiple times; and
in operation of the optical system:
the light beam reflected from the first reflector is incident on the second reflector and reflected by the second reflector back to the first reflector;
the light beam is incident on the first reflector first, before being incident on any other of the reflectors;
the light beam is last reflected by the first reflector such that, after the last reflection from the first reflector, the light beam is not incident on any other of the reflectors; and
at least one of the first reflector or the second reflector is movable in an adjustment direction that is orthogonal to its respective incident and reflected light beam paths, thereby changing the number of passes for the reflector, to permit a length of the light beam between the first reflector and the second reflector to be adjusted in discrete steps.
15. The optical delay line of claim 14 , wherein at least one of the reflectors is provided with at least one reflecting surface and at least one light beam passage said light beam passage being located on the at least one reflecting surface and being configured to allow transmission of the light beam therethrough.
16. The optical delay line of claim 14 , wherein at least one of the reflectors is configured so as to be movable in a second adjustment direction, the parallel to its respective incident and reflected light beam paths.
17. An optical coherence tomography apparatus comprising an optical system capable to admit a light beam, the optical system comprising:
a plurality of reflectors comprising a first reflector and a second reflector, the plurality of reflectors being configured to reflect the light beam, wherein:
each of the reflectors is configured to reflect an incident light beam according to a number of passes, such that, for each pass of the number of passes, a path of the incident light beam and a path of the reflected light beam are parallel to each other;
each of the reflectors has a reflector center axis positioned centrally between the path of the incident light beam and the path of the reflected light beam; and
the first reflector and the second reflector are arranged relative to each other such that their respective reflector center axes do not overlap, thereby enabling the path of the light beam to pass at least one of the first reflector or the second reflector multiple times; and
in operation of the optical system:
the light beam reflected from the first reflector is incident on the second reflector and reflected by the second reflector back to the first reflector;
the light beam is incident on the first reflector first, before being incident on any other of the reflectors;
the light beam is last reflected by the first reflector such that, after the last reflection from the first reflector, the light beam is not incident on any other of the reflectors; and
at least one of the first reflector or the second reflector is movable in an adjustment direction that is orthogonal to its respective reflector center axis, thereby changing the number of passes in which incident light and reflected light are parallel, to permit a length of the light beam between the first reflector and the second reflector to be adjusted in discrete steps according to the changed number of passes.
18. The optical coherence tomography apparatus of claim 17 , wherein at least one of the reflectors is configured so as to be movable in a second adjustment direction parallel to the reflector center axis of the at least one reflector.
19. An optical coherence tomography apparatus comprising an optical delay line, the optical delay line comprising an optical system capable to admit a light beam, the optical system comprising:
a plurality of reflectors comprising a first reflector and a second reflector, the plurality of reflectors being configured to reflect the light beam, wherein:
each of the reflectors is configured to reflect an incident light beam according to a number of passes, such that, for each pass of the number of passes, a path of the incident light beam and a path of the reflected light beam are parallel to each other;
each of the reflectors has a reflector center axis positioned centrally between the path of the incident light beam and the path of the reflected light beam; and
the first reflector and the second reflector are arranged relative to each other such that their respective reflector center axes do not overlap, thereby enabling the path of the light beam to pass at least one of the first reflector or the second reflector multiple times; and
in operation of the optical system:
the light beam reflected from the first reflector is incident on the second reflector and reflected by the second reflector back to the first reflector;
the light beam is incident on the first reflector first, before being incident on any other of the reflectors;
the light beam is last reflected by the first reflector such that, after the last reflection from the first reflector, the light beam is not incident on any other of the reflectors; and
at least one of the first reflector or the second reflector is movable in an adjustment direction that is orthogonal to its respective reflector center axis, thereby changing the number of passes in which incident light and reflected light are parallel, to permit a length of the light beam between the first reflector and the second reflector to be adjusted in discrete steps.
20. The optical coherence tomography apparatus of claim 19 , wherein at least one of the reflectors is configured so as to be movable in a second adjustment direction parallel to the reflector center axis of the at least one reflector.