Disclosed are several technical approaches of using low coherence interferometry techniques to create an autofocus apparatus for optical microscopy. These approaches allow automatic focusing on thin structures that are positioned closely to reflective surfaces and behind refractive material like a cover slip, and automated adjustment of focus position into the sample region without disturbance from reflection off adjacent surfaces. The measurement offset induced by refraction of material that covers the sample is compensated for. Proposed are techniques of an instrument that allows the automatic interchange of imaging objectives in a low coherence interferometry autofocus system, which is of major interest in combination with TDI (time delay integration) imaging, confocal and two-photon fluorescence microscopy.

A velocity-compensated frequency sweeping interferometer has a single measurement light producing device that produces a coherent light source consisting of a single light beam. The light producing device produces a scanning wavelength light beam. A primary beam splitter produces a first reference beam and a first measurement beam from said single light beam. The first reference beam travels a fixed path length to a primary reference reflector and the first measurement beam travels to and from a moveable reflective target over an unknown path length. A distance measurement interferometer is created by interfering the first reference beam with the first measurement beam. A return frequency measurement interferometer provides a measure of frequency of the return beam from the target which, when compared with the frequency of the outgoing beam, allows for velocity compensation of the target.

A multi-mode frequency sweeping interferometer has a single measurement light producing device configured to produce a coherent light source consisting of a single light beam. The single measurement light producing device transitions the single light beam between a fixed light beam and a scanning wavelength light beam. A primary beam splitter produces a first reference beam and a first measurement beam from said single light beam. The first reference beam is configured to travel a fixed path length to a primary reference reflector and the first measurement beam is configured to travel to and from a moveable reflective target over an unknown path length. A first interferometer is created by interfering the first reference beam with the first measurement beam and one or more optoelectronic devices may be configured to determine a measured distance to the movable reflective target.

The tomographic image capturing device of the present invention comprises a display means (18) configured to: split light from a light source (11) into measurement light and reference light and cause the measurement light and the reference light to be incident to an object (E) and a reference object (49), respectively; capture tomographic images of the object (E) on the basis of interference light generated by superposition of the measurement light reflected from the object (E) and the reference light reflected from the reference object (49); and display tomographic pictures of the object generated on the basis of the captured tomographic images. The tomographic image capturing device has a first image capturing mode and a second image capturing mode. The first image capturing mode is a mode in which the measurement light is two-dimensionally scanned by raster scan to be incident to the object (E) and the tomographic images of the object (E) are captured. The second image capturing mode is a mode in which the measurement light is two-dimensionally scanned by raster scan to be incident to the object (E) and the tomographic images of the object (E) are captured. The raster scan in the second image capturing mode is thinned from the raster scan in the first image capturing mode. The display means (18) is configured to be switchable between a first display mode and a second display mode. The first display mode is a mode in which a plurality of tomographic pictures including a region of interest of the object (E) is selected from among the tomographic pictures generated on the basis of the tomographic images captured in the second image capturing mode and only the selected plurality of tomographic pictures is displayed. The second display mode is a mode in which all of the tomographic pictures generated on the basis of the tomographic images captured in the second image capturing mode are in turn displayed. The capturing of the tomographic images in the first image capturing mode is performed after separately performing a first adjustment operation and a second adjustment operation for adjustment of an image capturing condition necessary for capturing the tomographic images in the first image capturing mode. The first adjustment operation is based on the tomographic pictures displayed in the first display mode. The second adjustment operation is based on the tomographic pictures displayed in the second display mode.

An image data set acquired by an optical coherence tomography (OCT) system is corrected for effects due to motion of the sample. A first set of A-scans is acquired within a time short enough to avoid any significant motion of the sample. A second more extensive set of A-scans is acquired over an overlapping region on the sample. Significant sample motion may occur during acquisition of the second set. A-scans from the first set are matched with A-scans from the second set, based on similarity between the longitudinal optical scattering profiles they contain. Such matched pairs of A-scans are likely to correspond to the same region in the sample. Comparison of the OCT scanner coordinates that produced each A-scan in a matching pair, in conjunction with any shift in the longitudinal scattering profiles between the pair of A-scans, reveals the displacement of the sample between acquisition of the first and second A-scans in the pair. Estimates of the sample displacement are used to correct the transverse and longitudinal coordinates of the A-scans in the second set, to form a motion-corrected OCT data set.

Systems and methods for enhanced accuracy in optical coherence tomography imaging of the cornea are presented, including approaches for more accurate corneal surface modeling, pachymetry maps, keratometric values, and corneal power. These methods involve new scan patterns, an eye tracking mechanism for transverse motion feedback, and advanced motion correction algorithms. In one embodiment the methods comprise acquiring a first sparse set of data, using that data to create a corneal surface model, and then using the model to register a second set of denser data acquisition. This second set of data is used to create a more accurate, motion-corrected model of the cornea, from which pachymetry maps, keratometric values, and corneal power information can be generated. In addition, methods are presented for determining simulated keratometry values from optical coherence tomography data, and for better tracking and registration by using both rotation about three axes and the corneal apex.

Systems and methods for improved interferometric imaging are presented. One embodiment is a partial field frequency-domain interferometric imaging system in which a light beam is scanned in two directions across a sample and the light scattered from the object is collected using a spatially resolved detector. The light beam could illuminate a spot, a line or a two-dimensional area on the sample. Additional embodiments with applicability to partial field as well as other types of interferometric systems are also presented.

An optical measuring device is provided. An actuator of a reference mirror set drives a reference mirror to move back and forth at a scan velocity. A first light source module transmits a first light beam to an optical coupling module transmitting two parts of the first light beam respectively to an examinee object and the reference mirror set. The first light beam then is reflected by the examinee object and reference mirror set and then transmitted to the optical coupling module and the processing unit. The second light source module transmits a second light beam to the examinee object. Then the second light beam is reflected and then transmitted to the second sensing unit. The second sensing unit provides a sensing signal to the processing unit which accordingly provides a value of the relative velocity. The thickness is calculated according to the relative velocity and the scan velocity.

A method for compensating the artifacts generated by moving measurement objects in measurement signals of swept-source OCT systems by moving measurement objects. Signal reconstruction is implemented without the aid of additional reference signals in respect of the movement of the measurement object and only by way of especially adapted algorithms. Example methods relate firstly to the especially adapted, Fourier transform-based algorithms for processing the captured measurement signals and secondly to the measurement signals to be captured, in particular to the optical coherence interferometry-based measurement systems used for the production thereof. Although the proposed method is provided for applications in ophthalmology in particular, it can be used, in principle, wherever signals reflected by curved surfaces or backscattered from structures are analyzed.

A method for compensating the artifacts generated by moving measurement objects in measurement signals of swept-source OCT systems by moving measurement objects. Signal reconstruction is implemented without the aid of additional reference signals in respect of the movement of the measurement object and only by way of especially adapted algorithms. Example methods relate firstly to the especially adapted, Fourier transform-based algorithms for processing the captured measurement signals and secondly to the measurement signals to be captured, in particular to the optical coherence interferometry-based measurement systems used for the production thereof. Although the proposed method is provided for applications in ophthalmology in particular, it can be used, in principle, wherever signals reflected by curved surfaces or backscattered from structures are analyzed.