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US 5,847,827 AGranted
Coherence biometry and coherence tomography with dynamic coherent
AssigneeCarl Zeiss Jena GmbH
InventorAdolf Friedrich Fercher
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AssigneeCarl Zeiss Jena GmbH
InventorAdolf Friedrich Fercher
Estimating the term…
In the application of coherence distance measurement in medical biometry and in medical coherence tomography, an interferometric measurement light path is directed on the object to be measured and is focussed in order to improve the transverse resolution. Since the focus of the measurement light beam is fixed in the axial direction, high transverse resolution cannot be achieved over the entire object depth at all interferometric measurement points along the measurement light beam. This problem is not solved merely by displacing the focus along the measurement beam, since the focus will then lose coherence with respect to the reference light and the actual interferometric measurement location will then lie outside of this focus. In accordance with the invention, a simultaneous displacement of the reference light mirror be effected synchronously with the displacement of the focus by virtue of the optics generating the focus in order to maintain the coherence of the focus. The invention provides a method in which the focus is displaced and the coherence of the focus is maintained by one and the same moving optical element.
In a method for coherence biometry and coherence tomography with increased transverse resolution for measuring the position of light-reflecting locations along a measurement path at the surface of and in the interior of objects by means of a measurement light path of a short-coherence interferometer, in which, for the purpose of achieving interference, the path lengths of the measurement arm and the reference arm are balanced to the same optical length and the positions of the light-reflecting locations in the object along the measurement path are determined from the changes in length of the measurement light path and/or reference light path which are required for these positions to balance the path lengths, wherein the measurement light path is focussed in or on the object to be measured and the measurement focus produced in this way is moved along the measurement path in such a way that it remains coherent with respect to the reference light during the scanning movement, the improvement comprising the step of:
In an arrangement for coherence biometry and coherence tomography with increased transverse resolution for measuring the position of light-reflecting locations along a measurement path at the surface of and in the interior of objects by means of a measurement light path of a short-coherence interferometer, in which, for the purpose of achieving interference, the path lengths of the measurement arm and the reference arm are balanced to the same optical length and the positions of the light-reflecting locations in the object along the measurement path are determined from the changes in length of the measurement light path and/or reference light path which are required for these positions to balance the path lengths, wherein the measurement light path is focussed in or on the object to be measured and the measurement focus produced in this way is moved along the measurement path in such a way that it remains coherent with respect to the reference light during the scanning movement, the improvement comprising:
In a method for coherence biometry and coherence tomography according to the dual-beam method with increased transverse resolution for measuring the position of light-reflecting locations along a measurement path at the surface of and in the interior of objects based on short-coherence interferometry, in which the object to be measured is illuminated by a dual beam formed of a measurement light beam and a reference light beam exiting from a two-beam interferometer and in which, for the purpose of achieving interference in the light returning from the object to be measured, the path lengths of the measurement arm and the reference arm of said two-beam interferometer are balanced to the same optical length and the positions of the light-reflecting locations in the object along the measurement path are determined from the changes in length in the measurement arm and/or reference arm which are required for these positions for equilibrium, wherein the reference beam is reflected at a stationary light-reflecting location of the object, while the measurement beam is focussed in or on the measurement object, and the measurement focus produced in this way is moved along the measurement path during the measurement, the improvement comprising the step of:
In an arrangement for coherence biometry and coherence tomography according to the dual-beam method with increased transverse resolution for measuring the position of light-reflecting locations along a measurement path at the surface of and in the interior of objects based on short-coherence interferometry, in which the object to be measured is illuminated by a dual beam formed of a measurement light beam and a reference light beam exiting from a two-beam interferometer and in which, for the purpose of achieving interference in the light returning from the object to be measured, the path lengths of the measurement arm and the reference arm of said two-beam interferometer are balanced to the same optical length and the positions of the light-reflecting locations in the object along the measurement path are determined from the changes in length in the measurement arm and/or reference arm which are required for these positions for equilibrium, wherein the reference beam is reflected at a stationary light-reflecting location of the object, while the measurement beam is focussed in or on the measurement object, and the measurement focus produced in this way is moved along the measurement path during the measurement, the improvement comprising:
An arrangement for scanning an object, comprising:
Dependencies are inferred from the claim text.