DEVICE FOR MEASURING THE PARAMETERS OF PHASE ELEMENTS AND OPTICAL FIBER DISPERSION AND A METHOD OF MEASURING THE PARAMETERS OF PHASE ELEMENTS AND OPTICAL FIBER DISPERSION

Abstract

A device for measuring the parameters of phase elements and dispersion of optical fibers, characterized in that it contains: a light source, serially connected to fiber optic coupler, one of whose arms constitutes a part of the reference arm, and whose second arm constitutes a part of the measurement arm of the device, and a motorized linear stage is mounted on the arm of the device. One of the arms of the device is connected to at least one detector, and at least one collimator is placed in at least of the arms of the device, at least before the phase element. A method of measuring the parameters of the phase element and the dispersion of optical fibers is conducted in two stages, wherein the first stage assumes the calibration of the device and the second stage is the proper measurement.

Claims

1. A device for measuring the parameters, especially thickness or refractive index or dispersion of phase elements, characterized in that the device contains: at least one fiber optic coupler (2.1), at least one low-coherence light source (1.1), serially connected to at least one input fiber optic coupler (2.1), one of whose arms constitutes a part of a reference arm, and whose second arm constitutes a part of a measurement arm of the device, and at least one motorized linear stage (6) is mounted on at least one arm of the device, and at least one of the arms of the device is connected, either directly, or through an additional output fiber optic coupler (2.2), to at least one detector (7.1; 7.2), and at least one collimator (3.1; 3.2; 4.1; 4.2) is placed in at least one of the arms of the device, at least before the measured phase element (5.1; 5.2; 5.3; 5.4; 11).

2. (canceled)

3. The device according to claim 1, characterized in that a model phase element (5.2) selected from among lenses, plane-parallel plates, optical fibers or other, is mounted in the measurement arm.

4. The device according to claim 1, characterized in that a photodiode is the detector (7.1; 7.2).

5. The device according to claim 3, characterized in that the measurement arm according to the invention contains: the optical fiber comprising the input fiber optic coupler (2.1), the first collimator (3.1) located in the end of the optical fiber comprising the input fiber optic coupler (2.1), free space, in which the phase element (5.1, 5.3, 5.4) is mounted in a handle for the duration of the measurement, the second collimator (3.2) located in the beginning of the optical fiber comprising the output fiber optic coupler (2.2), and the reference arm of the device according to the invention comprises: the optical fiber consisting: the input fiber optic coupler (2.1), the third collimator (4.1) located in the end of the optical fiber comprising the input fiber optic coupler, free space, the fourth collimator (4.2) located in the beginning of optical fiber comprising the output fiber optic coupler (2.2), whereas one of the collimators (4.1) or (4.2) or (3.1) or (3.2) is mounted on a motorized linear stage (6).

6. (canceled)

7. The device according to claim 1, characterized in that the measured phase element (5.1; 5.3; 5.4), particularly a measured lens, is placed in the free space of the measurement arm, after the first collimator (3.1), which is placed in the terminal of the optical fiber comprising the input fiber optic coupler (2.1), and before the collimator (43.2) is placed on the motorized linear stage (6), and the optical fiber comprising the input fiber optic coupler (2.1) which is not terminated with a collimator, is connected, either directly or through another optical fiber, to the optical fiber comprising the output fiber optic coupler (2.2) which is not terminated with a collimator.

8. The device according to claim 1, characterized in that the high-dispersion optical fiber (11) is connected to the optical fibers comprising the fiber optic couplers (2.1) and (2.2), and the connection is performed by fiber splicing or butt coupling or otherwise, and the second arm of the device according to the invention contains the collimator (3.1) and collimator (3.2), mutually and serially connected, and the collimator (3.2) is placed on the motorized linear stage (6), which are parallel to the high dispersion optical fiber (11) and the high-dispersion optical fiber (11) and the collimator system (3.1) and (3.2) are connected to the fiber optic coupler (2.2) connected to detector (7.1).

9. (canceled)

10. The device according to claim 1, characterized in that the device contains a second, coherent light source (1.2) is applied apart from the low-coherence light source (1.1), cross-connected to the device in relation to the first light source (1.1), and the output signal from the low-coherence light source (1.1) is directed through the input fiber optic coupler (2.1) to the reference and measurement arms, and then reaches the detector (7.1) through the connected output fiber optic coupler (2.2) and a second, coherent light source (1.2) is connected to the second optical fiber comprising the output fiber optic coupler (2.2), from which, through the measurement arm and the reference arm, signal is directed to the input fiber optic coupler (2.1) and to the second detector (7.2).

11. The device according to claim 1, characterized in that at least one light source (1.1) is connected to the input fiber optic coupler (2.1) whose optical fibers comprising a part of the measurement arm and reference arm are terminated with collimators (3.1, 4.1), one of which is connected to a motorized linear stage (6) to which a mirror (10.1) is connected, and the phase element (5.1; 5.3; 5.4) is mounted in the measurement arm area at the stage of conducting proper measurement.

12. The device according to claim 11, characterized in that an additional mirror (10.1) is placed behind the measured phase element (5.1, 5.2, 5.3, 5.4).

13. (canceled)

14. The device according to claim 1, characterized in that the motorized linear stage (6) moves along at least one axis, and the handle of the phase element (5.1; 5.2; 5.3; 5.4) moves along three axes or enables rotation around any of these axes.

15. A method of measuring the parameters especially thickness or refractive index or dispersion of the phase element (5.1; 5.2; 5.3; 5.4; 11), applying the device according to claim 1, characterized in that it is two-staged, wherein the first stage assumes the calibration of the device according to the invention, and the second stage is the proper measurement, characterized in that during calibration of the device according to the invention, light from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), where it is separated into two arms: measuring and reference, and then the motorized linear stage (6) moves, recording information on its position until zero difference of optical paths between particular fiber optic coupler arms is obtained, interferogram is collected in time delay, by a detector (7.1; 7.2), and after the device is calibrated, the system proceeds to proper measurement, in which the phase element, is inserted in the measurement arm of the device according to the invention, after which, sliding the motorized linear stage, the position producing zero optical path difference is determined, and the selected parameter of the phase element is determined on the basis of differential positions of the motorized linear stage for the zero optical path difference in the calibration, and in the proper measurements.

16. The method according to claim 11, characterized in that the calibration and proper measurements are performed in one scanning in the reflective configuration of the device according to the invention.

17. The method according to claim 15, characterized in that during measurement signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1), and after leaving the collimator (3.1) in the measurement arm, light is directed to the phase element (5.1; 5.3; 5.4), after which it is directed to a collimator (3.2), and after leaving the collimator (4.1), it illuminates a collimator (4.2) in the reference arm, where the length of the measurement arm or reference arm depends on the shift of the motorized linear stage (6), and signals from collimators (3.2 and 4.2) are directed to a fiber optic coupler (2.2), where they interfere, and signal from the fiber optic coupler is directed to a detector (7.1).

18. The method according to claim 15, characterized in that when applying a second, coherent light source apart from the low-coherence light source, signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1), and after leaving the collimator (3.1), light is directed to the phase element (5.1; 5.3; 5.4) in the measurement arm, after which it is directed to a collimator (3.2), and after leaving the collimator (4.1), it reaches a collimator (4.2) in the reference arm, the position of which depends on the shift of the motorized linear stage (6), and signals from collimators (3.2 and 4.2) are directed to a fiber optic coupler (2.2), where they interfere, and signal from the fiber optic coupler is directed to a detector (7.1), while on the other side of the system, signal from the coherent light source (1.2) is directed to the fiber optic coupler (2.2), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.2) and (4.2), and after leaving the collimator (3.2), light is directed to the phase element (5.1, 5.3, 5.4) in the measurement arm, after which it is directed to a collimator (3.1), and signal from the collimator (4.2) is directed to a collimator (4.1) in the reference arm, where the length of the reference optical path depends on the said shift of the motorized linear stage (6), and signals from collimators (3.1) and (4.1) are directed to a fiber optic coupler (2.1), where they interfere, and signal from the fiber optic coupler is directed to a detector (7.2).

19. The method according to claim 15, characterized in that when applying the model phase element (5.2) placed in the reference arm, signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1), and after leaving the collimator (3.1), light is directed to the phase element (5.1, 5.3, 5.4) in the measurement arm, after which it is directed to a collimator (3.2), and after leaving the collimator (4.1), it reaches the model phase element (5.2) and then a collimator (4.2) in the reference arm, where the length of the reference optical path depends on the shift of the motorized linear stage (6), and signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere, and signal from the fiber optic coupler is directed to a detector (7.1).

20. The method according to claim 15, characterized in that when measuring the curve of the phase element, signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1), and after leaving the collimator (3.1), light is directed to the phase element (5.1, 5.3, 5.4) in the measurement arm, after which it is directed to a collimator (3.2), and the phase element (5.1; 5.3; 5.4) is mounted in a system enabling its movement along axes X and Y (8), and after leaving the collimator (4.1), light reaches a collimator (4.2) in the reference arm, where the length of the reference optical path depends on the shift of the motorized linear stage (6), and signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere, and signal from the fiber optic coupler is directed to a detector (7.1).

21. The method according to claim 15, characterized in that when measuring the refractive index, signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1), and after leaving the collimator (3.1), light is directed to the phase element (5.1, 5.3, 5.4) in the measurement arm, after which it is directed to a collimator (3.2), and the phase element (5.1, 5.3, 5.4) is mounted in a system enabling its rotation by a present angle (9), and after leaving the collimator (4.1), light reaches a collimator (4.2) in the reference arm, where the length of the reference optical path depends on the shift of the motorized linear stage (6), and signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere, and signal from the fiber optic coupler is directed to a detector (7.1).

22. The method according to claim 15, characterized in that when performing measurement with collimators mounted in one arm onlyin the measurement arm of the fiber optic couplers, signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to a collimator (3.1), and after leaving the collimator (3.1), light is directed to the phase element (5.1, 5.3, 5.4) in the measurement arm, after which it is directed to a collimator (3.2), where the length of the reference optical path depends on the shift of the motorized linear stage (6), and after leaving the fiber optic coupler (2.1), light is transported by the optical fiber comprising the reference arm to the second fiber optic coupler (2.2), and signals from the measuring and reference arms are directed to the fiber optic coupler (2.2), where they interfere, and signal from the fiber optic coupler is directed to a detector (7.1).

23. The method according to claim 16, characterized in that when applying a system in the reflective configuration, signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to the collimator (3.1) and the collimator (4.1), and after leaving the collimator (3.1), light is directed to the phase element (5.1, 5.3, 5.4) in the measurement arm, after which it is reflected by a mirror (10.1) and through the lens (5.1) and collimator, it is directed back to the fiber optic coupler (2.1) and to the detector (7.1), after which the light directed to the collimator (4.1) is then directed to the mirror (10.1), the position of which depends on the shift of the motorized linear stage (6), and after leaving the fiber optic coupler (2.1), light is transported to the detector (7.1).

24. The method according to claim 15, characterized in that signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to the collimator (3.1) and the collimator (4.1), and after leaving the collimator (3.1), light is directed to the measured phase element (5.1, 5.3, 5.4) in the measurement arm on which signal reflects and then reflected light is directed back to the collimator (3.1), to the fiber optic coupler (2.1) and to the detector (7.1), and the light directed to the collimator (4.1) is then directed to the mirror (10.1), the position of which depends on the shift of the motorized linear stage (6), and reflected signal is directed back to the collimator (4.1), the fiber optic coupler (2.1) and is transported to the detector (7.1).

25. The method according to claim 15, characterized in that when performing measurement with collimators mounted on one arm onlyon the reference arm of the fiber optic couplers, signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to the optical fiber with high dispersion value (11) and the collimator (3.1), and after leaving the collimator (3.1), light is directed to the collimator (3.2), the position of which is regulated by the motorized linear stage (6), and signal from the optical fiber (11) and the signal leaving the collimator (3.2) interfere in the fiber optic coupler (2.2), and then is directed to the detector (7).

Description

[0047] The device according to the invention was presented in a figure, in which

[0048] FIG. 1 presents the invention in its basic version, in which signal from the low-coherent light source (1.1) is directed to a fiber optic coupler (2.1), then from optical fibers comprising the fiber optic coupler, signal passes to collimators (3.1) and (4.1).

[0049] FIG. 2 presents the invention applying coherent and low-coherence light sources,

[0050] FIG. 3 presents the invention in a variant used for measurements applying model phase element,

[0051] FIG. 4 presents the invention in a configuration for measuring the curve of the phase element,

[0052] FIG. 5 presents a beneficial embodiment of the invention, used for measuring the refractive index of plane-parallel plates, in which data for two various plate inclinations are collected,

[0053] FIG. 6 presents a beneficial embodiment of the invention in the so-called reduced version,

[0054] FIG. 7 presents a beneficial embodiment of the invention in a version applying reflective configuration basing on mirror reflections,

[0055] FIG. 8 presents another beneficial embodiment of the invention in a version applying reflective configuration basing on reflections from the surface of the phase element,

[0056] FIG. 9 presents a beneficial embodiment of the invention in a version for measuring the dispersion of optical fibers with high absolute dispersion values.

EXAMPLE 1

[0057] A device for measuring the parameters of phase elements and optical fiber dispersion comprising: a low-coherence light source, a detectorphotodiode, two fiber optic fiber optic couplers, a motorized linear stage, four collimators.

[0058] The measurement arm according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the phase elementa lens is mounted in a handle for the duration of measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler, and optical fiber comprising an output fiber optic coupler.

[0059] The reference arm of the device according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the phase elementa lens is mounted in a handle for the duration of measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler, and optical fiber comprising an output fiber optic coupler.

[0060] The length of the arms is divided into length in the optical fiber and length in the free space. The length of the arm in the optical fiber is standard, as listed in catalogue solutions applied in marketed fiber optic couplers and equals 1 m. The length of the arms in free space is 150 mm.

[0061] The light source is connected to the input fiber optic coupler whose optical fibers comprising a part of the measurement arm and reference arm are terminated with collimators, one of which is connected to a motorized linear stage, and a fiber optic coupler connected to a detector is connected to the other side of the measuring and reference arms. At the stage of measurement, a measured phase elementmeasured lensis mounted in the free space of the measurement arm.

[0062] The method of measuring the parameters of the phase element and the dispersion of optical fibers, applying the device according to the invention is two-staged, wherein the first stage assumes the calibration of the device according to the invention, and the second stage is the proper measurement.

[0063] During calibration of the device according to the invention, light from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), where it is separated into two arms: measuring and reference. Whereas, there are no phase elements in the free space of the measurement and reference arms.

[0064] Further on, the motorized linear stage (6) moves, registering information on its position until zero difference of optical paths between particular fiber optic coupler arms is obtained through an analysis of data from the detector and motorized linear stage positions. Interference takes place in the fiber optic coupler (2.2), after passing through the collimators (3.2) and (4.2), and interferogram is collected as the time function, which translates into motorized linear stage movement. Interferogram is collected by the photodetector, in particular by the photodiode.

[0065] After the device is calibrated, the system proceeds to proper measurement, in which a phase element, particularly a lens intended for measurement, is inserted in the measurement arm of the device according to the invention, between the collimators (3.1) and (3.2). Further on, sliding the motorized linear stage, the position producing zero optical path difference is determined. Basing on differential positions of the motorized linear stage for interferogram contrast maximums in the calibration measurement and in the proper measurement with the phase element, and having the refractive index of glass, from which the phase element was made, the thickness of the phase element, particularly the lens, is determined.

[0066] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1). After leaving the collimator (3.1), light is directed to a phase elementlens (5.1) in the measurement arm, after which it is directed to a collimator (3.2). After leaving the collimator (4.1), it reaches a collimator (4.2) in the second arm, the position of which depends on the shift of the motorized linear stage (6). Signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere. Signal from the fiber optic coupler is directed to a detector (7.1).

[0067] Due to high precision of refractive index defined in the available catalogs refractive index, we can determine the thickness of the phase element with high accuracy.

EXAMPLE 2

[0068] A device for measuring the parameters of phase elements and optical fiber dispersion comprising: a low-coherence and coherent light source, two detectors in the form of photodiodes, two fiber optic couplers, a motorized linear stage, four collimators.

[0069] The measurement arm according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the phase elementa lens is mounted in a handle for the duration of measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler, and optical fiber comprising an output fiber optic coupler.

[0070] The reference arm of the device according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler mounted on a motorized linear stage, and optical fiber comprising an output fiber optic coupler.

[0071] The length of the arms is divided into length in the optical fiber and length in the free space. The length of the arm in the optical fiber is standard, as listed in catalogue solutions applied in marketed fiber optic couplers and equals 1 m. The length of the arms in free space is 150 mm. Fiber optic couplers are fabricated from standard single-mode optical fibers.

[0072] The coherent light source and the detector are connected to the input fiber optic coupler whose optical fibers comprising a part of the measurement arm and reference arm are terminated with collimators, one of which is connected to a motorized linear stage, and the input fiber optic coupler connected to a second detector and the low-coherence light source is connected to the other side of the measurement and reference arms.

[0073] In the case of the coherent light source, the coherence length is higher or equal to the range of movement of the motorized linear stage.

[0074] The method of measuring the parameters of the phase element and the dispersion of optical fibers, applying the device according to the invention is two-staged, wherein the first stage assumes the calibration of the device according to the invention, and the second stage is the proper measurement.

[0075] During calibration of the device according to the invention, light from the low-coherence (1.1) and coherent (1.2) light source is directed to the fiber optic couplers (2.1) and (2.2), where it is separated into two arms: measurement and reference. Whereas, there are no phase elements in the free space of the measuring and reference arms.

[0076] The motorized linear stage moves, which causes interferogram to be registered for each of the sources. Further on, the motorized linear stage moves, recording information on its position until zero difference of optical paths between particular fiber optic coupler arms is read with the use of detectors. Interference takes place both fiber optic couplers, whereas one of them supports interference from the coherent source, and the secondfrom the low-coherence source. Interferograms are collected by photodetectors, in particular by photodiodes.

[0077] After the device is calibrated, the system proceeds to proper measurement, in which a phase element, particularly a lens intended for measurement, is inserted in the measurement arm of the device according to the invention, between the collimators (3.1) and (3.2). Further on, sliding the motorized linear stage, the position producing zero optical path difference is determined. Basing on differential positions of the motorized linear stage for interferogram contrast maximums in the calibration measurement and in the proper measurement with the phase element, and having the refractive index for glass, from which the phase element was made, the thickness of the phase element, particularly the lens, is determined.

[0078] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1). After leaving the collimator (3.1), light is directed to a phase elementlens (5.1) in the measurement arm, after which it is directed to a collimator (3.2). After leaving the collimator (4.1), it reaches a collimator (4.2) in the second arm, the position of which depends on the shift of the motorized linear stage (6). Signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere. Signal from the fiber optic coupler is directed to a detector (7.1). On the other side of the system, signal from the coherent light source (1.2) is directed to the fiber optic coupler (2.2), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.2) and (4.2). After leaving the collimator (3.2), light is directed to a phase elementlens (5.1) in the measurement arm, after which it is directed to a collimator (3.2). After leaving the collimator (4.2), it reaches a collimator (4.1) in the second arm, the position of which depends on the shift of the motorized linear stage (6). Signals from collimators (3.1) and (4.1) are directed to a fiber optic coupler (2.1), where they interfere. Signal from the fiber optic coupler is directed to a detector (7.2). Thanks to the occurrence of a second light source (coherent), it is possible to increase the precision of measurement of the motorized linear stage position.

[0079] Due to high precision of refractive index defined in the available catalogs refractive index, we can determine the thickness of the phase element with high accuracy.

EXAMPLE 3

[0080] A device for measuring the parameters of phase elements and optical fiber dispersion comprising: a low-coherence light source, a detectorphotodiode, two fiber optic couplers, a motorized linear stage, four collimators. As part of measurement, the specification of the measured phase element is determined on the basis of a model phase elementa model lens with familiar optical parameters and dimensions.

[0081] The measurement arm according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the phase elementa lens is mounted in a handle for the duration of measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler, and optical fiber comprising an output fiber optic coupler.

[0082] The reference arm of the device according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the model phase elementa model lens is mounted in a handle for the duration of proper measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler mounted on a motorized linear stage, and optical fiber comprising an output fiber optic coupler.

[0083] The length of the arms is divided into length in the optical fiber and length in the free space. The length of the arm in the optical fiber is standard, as listed in catalogue solutions applied in marketed fiber optic couplers and equals 1 m. The length of the arms in free space is 150 mm.

[0084] The light source is connected to the input fiber optic coupler whose optical fibers comprising a part of the measurement arm and reference arm are terminated with collimators, one of which is connected to a motorized linear stage, and a fiber optic coupler connected to a detector is connected to the other side of the measuring and reference arms. At the stage of measurement, a measured phase elementmeasurement lensis mounted in the free space of the measurement arm, and a model phase elementmodel lens is mounted in the reference arm. The model phase element is mounted on a motorized linear stage.

[0085] The method of measuring the parameters of the phase element and the dispersion of optical fibers, applying the device according to the invention is two-staged, wherein the first stage assumes the calibration of the device according to the invention, and the second stage is the proper measurement.

[0086] During calibration of the device according to the invention, light from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), where it is separated into two arms: measuring and reference. Whereas, there are no phase elements in the free space of the both arms.

[0087] Further on, the motorized linear stage (6) moves, recording information on its position until zero difference of optical paths between particular fiber optic coupler arms is read using a detector. Interference takes place in the fiber optic coupler (2.2), after passing through the collimators (3.2) and (4.2), and interferogram is collected as the time function, which translates into motorized linear stage movement. Interferogram is collected by the photodetector, in particular by the photodiode.

[0088] After the device is calibrated, the system proceeds to proper measurement, in which a phase element, particularly a lens intended for measurement, is inserted in the measurement arm of the device according to the invention, between the collimators (3.1) and (3.2). In addition, a model phase element consisting in a model lens with familiar parameters is placed between the collimators in the reference arm (4.1) and (4.2). Further on, sliding the motorized linear stage, the position producing zero optical path difference is determined. Basing on differential positions of the motorized linear stage for interferogram contrast maximums in the calibration measurement and in the proper measurement with the phase element, and having the refractive index for glass, from which the phase element was made, the thickness of the phase element, particularly the lens, is determined.

[0089] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1). After leaving the collimator (3.1), light is directed to a phase elementlens (5.1) in the measurement arm, after which it is directed to a collimator (3.2). After leaving the collimator (4.1), it reaches a model lens (5.2) and then a collimator (4.2) in the second arm, the position of which depends on the shift of the motorized linear stage (6). Signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere. Signal from the fiber optic coupler is directed to a detector (7.1).

[0090] Due to high precision of refractive index defined in the available catalogs refractive index, we can determine the thickness of the phase element with considerable accuracy.

EXAMPLE 4

[0091] A device for measuring the parameters of phase elements and optical fiber dispersion comprising: a low-coherence light source, a detectorphotodiode, two fiber optic couplers, a motorized linear stage, one system allowing for movement along axes X and Y, four collimators. As part of measurement, the specification of the measured phase element, flat on the one side, is determined when the phase element is placed in a system enabling its movement along axes X and Y.

[0092] The measurement arm according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the phase elementa lens is mounted in a handle that enables its movement along axes X and Y for the duration of measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler, and optical fiber comprising an output fiber optic coupler.

[0093] The reference arm of the device according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the model phase elementa model lens is mounted in a handle for the duration of proper measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler mounted on a motorized linear stage, and optical fiber comprising an output fiber optic coupler.

[0094] The length of the arms is divided into length in the optical fiber and length in the free space. The length of the arm in the optical fiber is standard, as listed in catalogue solutions applied in marketed fiber optic couplers and equals 1 m. The length of the arms in free space is 150 mm.

[0095] The light source is connected to the input fiber optic coupler whose optical fibers comprising a part of the measurement arm and reference arm are terminated with collimators, one of which is connected to a motorized linear stage, and a fiber optic coupler connected to a detector is connected to the other side of the measuring and reference arms. At the stage of measurement, a measured phase elementflat on the one side and placed on a motorized linear stageis mounted in the measuring optical fiber area.

[0096] The method of measuring the parameters of the phase element and the dispersion of optical fibers, applying the device according to the invention is two-staged, wherein the first stage assumes the calibration of the device according to the invention, and the second stage is the proper measurement.

[0097] During calibration of the device according to the invention, light from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), where it is separated into two arms: measuring and reference. Whereas, there are no phase elements in the free space of the both arms.

[0098] Further on, the motorized linear stage (6) moves, recording information on its position until zero difference of optical paths between particular fiber optic coupler arms is read using a detector. Interference takes place in the fiber optic coupler (2.2), after passing through the collimators (3.2) and (4.2), and interferogram is collected as the time function, which translates into motorized linear stage movement. Interferogram is collected by the photodetector, in particular by the photodiode.

[0099] After the device is calibrated, the system proceeds to proper measurement, in which a phase element, particularly a lens intended for measurement, is inserted in the measurement arm of the device according to the invention, between the collimators (3.1) and (3.2). Further on, sliding the motorized linear stages, the position producing zero optical path difference is determined. Whereas measurement is conducted in several spots, sliding the measured phase element. Basing on differential positions of the motorized linear stage for interferogram contrast maximums in the calibration measurement and in the proper measurement with the phase element, and having the refractive index for glass, from which the phase element was made, the thickness of the phase element, particularly the lens, is determined.

[0100] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1). After leaving the collimator (3.1), light is directed to a phase elementflat on the one side (5.3) in the measurement arm, after which it is directed to a collimator (3.2). The flat measured phase element (5.3) is mounted in a system enabling its movement along axes X and Y (8). After leaving the collimator (4.1), light reaches a collimator (4.2) in the second arm, the position of which depends on the shift of the motorized linear stage (6). Signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere. Signal from the fiber optic coupler is directed to a detector (7.1).

[0101] Due to high precision of refractive index defined in the available catalogs refractive index, we can determine the thickness of the phase element with considerable accuracy.

EXAMPLE 5

[0102] A device for measuring the parameters of phase elements and optical fiber dispersion comprising: a low-coherence light source, a detectorphotodiode, two fiber optic couplers, a motorized linear stage, four collimators. As part of measurement, the specification of the measured phase element mounted on one of the motorized linear stages.

[0103] The measurement arm according to the invention comprises: optical fiber comprising an input coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which the phase elementa plane-parallel lens is mounted in a handle for the duration of measurement, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler, and optical fiber comprising an output fiber optic coupler.

[0104] The reference arm of the device according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler mounted on a motorized linear stage, and optical fiber comprising an output fiber optic coupler.

[0105] The length of the arms is divided into length in the optical fiber and length in the free space. The length of the arm in the optical fiber is standard, as listed in catalogue solutions applied in marketed fiber optic couplers and equals 1 m. The length of the arms in free space is 150 mm. Fiber optic couplers are fabricated out of standard single-mode optical fibers.

[0106] The light source is connected to the input fiber optic coupler whose optical fibers comprising a part of the measurement arm and reference arm are terminated with collimators, one of which is connected to a motorized linear stage, and a fiber optic coupler connected to a detector is connected to the other side of the measuring and reference arms. At the stage of measurement, a measured phase elementa plane-parallel plate placed on a motorized linear stageis mounted in the measuring optical fiber area.

[0107] The method of measuring the parameters of the phase element and the dispersion of optical fibers, applying the device according to the invention is two-staged, wherein the first stage assumes the calibration of the device according to the invention, and the second stage is the proper measurement.

[0108] During calibration of the device according to the invention, light from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), where it is separated into two arms: measuring and reference. Whereas, there are no phase elements in the free space of the the reference and measurement arms.

[0109] Further on, the motorized linear stage (6) moves, recording information on its position until zero difference of optical paths between particular fiber optic coupler arms is read using a detector. Interference takes place in the fiber optic coupler (2.2), after passing through the collimators (3.2) and (4.2), and interferogram is collected as the time function, which translates into motorized linear stage movement. Interferogram is collected by the photodetector, in particular by the photodiode.

[0110] After the device is calibrated, the system proceeds to proper measurement, in which a phase elementa plane-parallel plate intended for measurement, is inserted in the measurement arm of the device according to the invention, between the collimators (3.1) and (3.2). Further on, sliding the motorized linear stages, the position producing zero optical path difference is determined. Whereas measurement is conducted in a manner that the measurement plate is rotated at least twice by familiar angles. Basing on differential positions of the motorized linear stage for interferogram contrast maximums in the calibration measurement and in the proper measurement with the phase element and the knowledge of rotation angles, the refractive index for the phase element is determined.

[0111] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to collimators (3.1) and (4.1). After leaving the collimator (3.1), light is directed to a plate (5.4) in the measurement arm, after which it is directed to a collimator (3.2). The plate (5.4) is mounted in a system enabling its rotation by a present angle (9). After leaving the collimator (4.1), light reaches a collimator (4.2) in the second arm, the position of which depends on the shift of the motorized linear stage (6). Signals from collimators (3.2) and (4.2) are directed to a fiber optic coupler (2.2), where they interfere. Signal from the fiber optic coupler is directed to a detector (7.1).

EXAMPLE 6

[0112] A device for measuring the parameters of phase elements and optical fiber dispersion comprising: a low-coherence light source, a detectorphotodiode, two fiber optic couplers, a motorized linear stage, two collimators. As part of measurement, the specification of the measured phase element mounted on a handle.

[0113] The reference arm according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, connected to optical fiber comprising an output fiber optic coupler.

[0114] The measurement arm of the device according to the invention comprises: optical fiber comprising an input fiber optic coupler, a collimator located in the end of the optical fiber comprising the input fiber optic coupler, free space, in which a lens mounted on a handle is located, a collimator located in the beginning of optical fiber comprising an output fiber optic coupler mounted on a motorized linear stage, and optical fiber comprising an output fiber optic coupler.

[0115] The length of the arms is divided into length in the optical fiber and length in the free space. The length of the arm in the optical fiber is standard, as listed in catalogue solutions applied in marketed fiber optic couplers and equals 1 m. The length of the arms in free space is 150 mm. Fiber optic couplers are fabricated out of standard single-mode optical fibers.

[0116] At the stage of measurement, a measured phase elementa measured lensis mounted in the measuring optical fiber area, and the collimator is mounted on the motorized linear stage.

[0117] The method of measuring the parameters of the phase element and the dispersion of optical fibers, applying the device according to the invention is two-staged, wherein the first stage assumes the calibration of the device according to the invention, and the second stage is the proper measurement.

[0118] During calibration of the device according to the invention, light from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), where it is separated into two arms: measuring and reference. Whereas, there are no phase elements in the free space of the measurement arm.

[0119] Further on, the motorized linear stage (6) moves, registering information on its position until zero difference of optical paths between particular fiber optic coupler arms is obtained. Interference takes place in the fiber optic coupler (2.2), after passing through the collimators (3.1) and (3.2), and interferogram is collected as the time function, which translates into motorized linear stage movement. Interferogram is collected by the photodetector, in particular by the photodiode.

[0120] After the device is calibrated, the system proceeds to proper measurement, in which a lens intended for measurement is inserted in the measurement arm of the device according to the invention, between the collimators (3.1) and (3.2). Further on, sliding the motorized linear stages, the position producing zero optical path difference is determined. Basing on differential positions of the motorized linear stage for interferogram contrast maximums in the calibration measurement and in the proper measurement with the phase element and the knowledge of the refractive index, the thickness of the phase element is determined.

[0121] Due to high precision of refractive index defined in the available catalogs refractive index, we can determine the thickness of the phase element with considerable accuracy.

[0122] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to the collimator (3.1). After leaving the collimator (3.1), light is directed to a lens (5.1) in the measurement arm, after which it is directed to a collimator (3.2), the position of which depends on the shift of the motorized linear stage (6). After leaving the fiber optic coupler (2.1), light is transported by the optical fiber comprising the reference arm to the second fiber optic coupler (2.2). Signals from the measuring and reference arms are directed to the fiber optic coupler (2.2), where they interfere. Signal from the fiber optic coupler is directed to a detector (7.1).

[0123] In this layout, the two collimators were resigned thus avoiding the necessity of adjusting these systems. The method is effective provided that the optical fibers comprising the system have small dispersion (which does not distort the measurement at a level which lowers the desired accuracy).

EXAMPLE 7

[0124] In another, beneficial embodiment of the inventionin a reflective configuration of the system, as presented in FIG. 7, the device comprises: preferably a low-coherence light source, preferably a detector, preferably one fiber optic coupler, preferably two mirrors, preferably two collimators. As part of measurement, the specification of the measured phase elementa measured lensis determined.

[0125] Whereas, compared to M-Z configuration, this embodiment of the device according to the invention enables larger impact of the phase element on the beam, since an electromagnetic wave passes through the lens twice. A need arises to increase movement precision in relation to the M-Z configuration since double passage of light through the system requires increased precision (a requirement according the Nyquist criterion), while maintaining the same range of scanning. In addition, the reflective configuration features back reflectionthe same power reaches the light source and the detector (which sometimes enforces the need to apply additional optical attenuators).

[0126] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to the collimator (3.1) and collimator (4.1). After leaving the collimator (3.1), light is directed to a lens (5.1) in the measurement arm, after which it is reflected by a mirror (10.1) and through the lens (5.1) and collimator, it is directed back to the fiber optic coupler (2.1) and to the detector (7.1). The light directed to the collimator (4.1) is then directed to the mirror (10.1), the position of which depends on the shift of the motorized linear stage (6). After leaving the fiber optic coupler (2.1), light is transported to the detector (7.1).

EXAMPLE 8

[0127] In another, beneficial embodiment of the inventionin a mirror-reflection configuration of the system, as presented in FIG. 8, the device comprises one low-coherence light source, a detector, a fiber optic coupler, a mirror, two collimators. As part of measurement, the specification of the measured phase element is determined.

[0128] The idea of measurement applying the reflective configuration does not differ from the measurement presented in example 7. The difference is the method of obtaining interference, which, in this case, occurs between signals reflected from the first and second measured surface of the phase element and the signal propagated in the reference arm: the physical operation principle remains unchanged.

[0129] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to the collimator (3.1) and collimator (4.1). After leaving the collimator (3.1), light is directed to a lens (5.1) in the measurement arm, after which it is reflected by the surface of the phase element and through the lens (5.1) and collimator, it is directed back to the fiber optic coupler (2.1) and to the detector (7.1). The light directed to the collimator (4.1) is then directed to the mirror (10.1), the position of which depends on the shift of the motorized linear stage (6). After leaving the fiber optic coupler (2.1), light is transported to the detector (7.1).

EXAMPLE 9

[0130] In another, beneficial embodiment of the invention, intended for measuring the dispersion of optical fibers of high absolute dispersion values, as presented in FIG. 8, the device comprises one low-coherence light source, a detector, a fiber optic coupler, a mirror, two collimators. As part of measurement, the specification of the measured phase element is determined.

[0131] The primary difference between this solution and the solutions presented in examples 1-7 is that the measurement arm is replaced with an arm in the form of optical fiber with absolutely high dispersion.

[0132] In the first stage of measurement, the length of the optical fiber (11) is measured. The optical fiber is coupled with optical fibers comprising the fiber optic couplers (2.1) and (2.2). The coupling is performed by optical fiber splicing, butt coupling or otherwise. Then, interferogram is collected in the motorized linear stage (6) as the shift function, similarly to the measurements of phase element parameters. The value of dispersion of the refractive index is obtained through mathematical analysis of the generated interferogram, considering information on the length of the optical fiber (11).

[0133] Signal from the low-coherence light source (1.1) is directed to the fiber optic coupler (2.1), then from the optical fibers comprising the fiber optic coupler, the signal passes to the optical fiber with high dispersion value (11) and the collimator (3.1). After leaving the collimator (3.1), light is directed to the collimator (3.2), the position of which is regulated by the motorized linear stage (6). Signal from the optical fiber (11) and the signal leaving the collimator (3.2) interfere in the fiber optic coupler (2.2). Then, the signal is directed to the detector (7.1).