Imaging system including scanner and modulator, and improved accuracy response method

Abstract

A system for providing accurate lateral mapping of an image acquired via a scanning mechanism includes a modulator synchronized with an imaging engine clock to generate image markers. The markers are then used to remove distortion and generate a spatially accurate mapping. A method for correcting image distortion by identifying modulations and removing distortion according to the modulation interval. A system and method applicable to ocular biometry and topography includes an OCT arrangement that images the entire eye while simultaneously scanning the cornea and retina, and an on-axis imaging system that assesses ocular surface quality.

Description

Technical Field

[0001] The present disclosure is directed to optical coherence tomography imaging systems and techniques that enable accurate mapping within other scanner-based imaging systems.

[0002] The present disclosure is directed to adjusting on an OCT image obtained using an OCT system to match results calculated based on images obtained using another system with different performance characteristics.

[0003] The present disclosure is directed to a preferred scanning geometry for optical biometrics.

Background Art

[0004] Optical coherence tomography (OCT) is an imaging technique widely used in medicine, metrology, and industrial applications. OCT technology can perform non-contact and high-resolution imaging in turbid media. This interference-based technique provides excellent sensitivity to the weak intensity of light backscattered or backreflected from a sample. The technique provides a unique means of visualizing topography as well as subsurface features and structures at micron-level resolution.

[0005] The interference signal provides accurate spatial mapping in the depth (axial) dimension of the sample. The lateral dimension of an OCT scan depends on the scanning mechanism of the light beam or the sample itself. Scanning can be horizontal and vertical, or circumferential or helical. Commercial OCT systems utilize a mechanical scanner to scan the beam, resulting in low spatial accuracy along the lateral direction. Mechanical scanners typically have a dynamic nature and cause distortion that changes over time. Due to this limitation, OCT lacks the ability to map surfaces with nanometer-level accuracy. The lateral scanning accuracy is expected to become more difficult as the speed of OCT systems increases because the requirements for mechanical scanners become higher.

[0006] Achieving an accurate OCT-based mapping system would eliminate the need for complementary mapping systems commonly used with OCT, such as ocular Placido topographs. Reflection-based topographs, such as Placido ring topographs, are effective for examining the quality of optical surfaces, but require a large space to accurately measure topographic information.

[0007] There is a need to provide accurate, distortion-free OCT images at all dimensions. Addressing this need will be beneficial for optical surface measurement, accurate mapping of the ocular surface for improved cataract and refractive surgery, and many other applications. A complementary, compact imaging system is needed that can help understand the optical health of an object.

[0008] In many cases, OCT images are used to provide quantitative data using image analysis techniques. For many diseases, tracking this data allows for monitoring the progression of a patient's disease over several years. The importance of consistently monitoring progression requires that the image quality of the OCT system remains consistent. Therefore, there are limitations to implementing significant image quality improvements in new systems, as improved images taken of the same patient may change the measured values.

[0009] There is a need to provide an improved system that can convert OCT images to achieve quantitative analysis similar to that of the legacy system without changing the image analysis method.

[0010] Because optical biosensing systems typically focus light into the anterior segment of the eye, a blurred spot almost always appears in the fovea. Axial length is the most important biosensor for IOL (intraocular lens) calculators, and therefore accurate measurement of distance within the fovea is essential.

[0011] Acquiring optical biometric data requires that the patient fixates on a target adjusted by the measurement system. Several methods have been proposed and implemented to provide fixation based on the anterior part of the eyeball, but none accurately represent actual foveal fixation. Other methods confirm foveal fixation, but because the foveal position is captured after the actual measurement, these methods are susceptible to errors due to eye movements. [Overview of the project] [Problems that the invention aims to solve]

[0012] There is a need to provide more accurate optical biosensing systems that incorporate precise and simultaneous fixation confirmation and correction. [Means for solving the problem]

[0013] Overview: Spatiotemporal Modulation and Demodulation System This disclosure relates to methods and systems for providing accurate lateral mapping of OCT imaging systems, single-pixel imaging systems, or other systems that utilize a scanner to generate multidimensional images. This technique is called spatio-temporal modulation-demodulation, or STMD for short.

[0014] In some embodiments, the system includes an imaging engine and an objective scanner. The objective scanner consists of an optical setup having a scanning mechanism. The setup is adjusted to scan an object and collect light and return it to the imaging engine. In the setup, an active modulator is inserted after the scanner and generates image markers in synchronization with the imaging engine's clock. In this embodiment, the modulator is placed after the scanner. The modulator is synchronized with the imaging engine's clock to generate image markers, and the modulator starts at a rate that generates image markers.

[0015] In some embodiments, the active modulator is started at a speed that produces a measurable marker on the image. For example, the modulator is clocked to produce at least one marker on at least one image element, and furthermore, the modulator is clocked at a speed that results in modulation which is an integer division of the imaging engine clock.

[0016] In some embodiments, the modulation causes at least one marker to appear on at least one image element, such as a pixel or an A-line.

[0017] In some embodiments, the modulation rate is clocked to an integer divider of the system's master clock.

[0018] In some embodiments, the imaging engine can be an A-line scanner for an OCT, comprising a light source, a beam splitter and combiner configuration, a reference arrangement, at least one detector, a processor, and a display.

[0019] In some embodiments, the imaging engine can be a single-pixel camera or detector.

[0020] In some embodiments, the imaging system can be a line-scanning camera.

[0021] In some embodiments, the imaging system can be LiDAR (Light Detection and Ranging).

[0022] In some embodiments, the active modulator is positioned within a substantially optical plane from which the scanning mechanism is imaged.

[0023] In some embodiments, the active modulator is located near the scanning mechanism.

[0024] In some embodiments, the active modulator is positioned distal to the optical element of the scanning light probe.

[0025] In some embodiments, the active modulator is installed anywhere in the optical path.

[0026] In some embodiments, the active modulator is installed after all the optical components of the system to eliminate the need to calibrate the mechanical drift of the scanner and the optical distortion of the optical components.

[0027] In some embodiments, the active modulator can be an acousto-optic modulator, a liquid crystal modulator, an electro-optic modulator, a piezoelectric element, a galvanometer scanner, a voice coil, or another type of modulator.

[0028] In some embodiments, the active modulator can introduce a phase delay to at least one image element.

[0029] In some embodiments, the active modulator can introduce an amplitude change to at least one image element.

[0030] In some embodiments, the active modulator can introduce a color change to at least one image element.

[0031] In some embodiments, the active modulator can introduce a change in sharpness or moiré pattern removal to the interference signal corresponding to at least one image element.

[0032] In some embodiments, the active modulator can decorrelate the speckle for at least one image element.

[0033] In some embodiments, the active modulator can introduce a change in image characteristics such as blurring to at least one image element.

[0034] In some embodiments, the active modulator can be replaced with a passive modulator.

[0035] In some embodiments, the passive modulator can incorporate spatial characteristics that cause a phase, intensity, or other shift in one or more imaging events.

[0036] In some embodiments, the system is used to provide accurate mapping of the eye surface for the purpose of developing a precise IOL computer or developing a 3D eye model for planning cataract or refractive surgery.

[0037] In some embodiments, the system is used to provide accurate mapping of optical or precision surfaces.

[0038] In some embodiments, at least one characteristic is added to the objective scanner to generate a fiducial that can be used to calibrate the image scale to precise spatial dimensions.

[0039] In some embodiments, at least one optical object is selected from the group consisting of optical fibers, cylindrical objects, specular reflectors, and scatterers.

[0040] In some embodiments, the optical object is integrated with the modulator. In some embodiments, the optical object is located at the end of the modulator.

[0041] In some embodiments, the reference optical path length is matched to the optical path length of the reference arm of the imaging engine.

[0042] In some embodiments, the reference is generated by optical interactions within the optical object without interfering with the reference arm of the imaging system.

[0043] In some embodiments, the reference is inserted outside the image region.

[0044] Overview: Image Processing Image markers generated using the STMD method can be processed to remove distortions from the image or to perform final measurements based on the image.

[0045] In some embodiments, a method for correcting image distortion includes: creating an image with a modulator that generates modulation of elements within the image; placing image markers distributed along the surface of the object in at least one image of the object including the surface; identifying the modulations; and removing distortion from individual images in a horizontal direction perpendicular to the z-direction of the imaging beam, according to the interval of the modulations in the horizontal dimension.

[0046] In some embodiments, z-modulation is removed from the A-line of the OCT by applying a shift along the z-direction.

[0047] In some embodiments, removing the phase delay applied to an image element is achieved by applying a phase shift on the conjugate data that is equal to the phase shift applied to the image element.

[0048] In some embodiments, the modulated elements are removed from the image.

[0049] In some embodiments, a second unmodulated image of an object without an image marker pattern is received, and distortion data calculated from the modulated image is applied to the unmodulated image to construct a corrected image.

[0050] In some embodiments, the method includes receiving a second modulated image of an object, which is modulated with an image marker pattern shifted from a pattern on a first set; identifying the shifted image markers; removing distortion within the second image according to the modulation interval; and constructing a corrected image using unmodulated portions from the first set and the second image.

[0051] In some embodiments, the method may include one or more of the following: calculating topographic information from a plurality of corrected images; performing spatial scaling of an image based on prior knowledge scaling within a portion of an image having spatial data; and / or performing spatial scaling of an image based on measurements of a known object to generate an image reference.

[0052] In some embodiments, the image reference is generated by inserting at least one optical element of known width and height, or at least two elements of known spacing, into an objective scanner used to capture an image.

[0053] In some embodiments, a method for correcting image distortion includes placing image markers, which are created by modulators that generate modulation of elements in an image, on multiple OCT images of an object including a surface; generating a topography map from the images; identifying modulation along the topography projection; and removing distortion from the topography map according to the modulation intervals.

[0054] In some embodiments, the topography map is interpolated to fill in the data in place of modulated image elements.

[0055] In some embodiments, z-modulation is removed by shifting the OCT's A-line in the z-direction before calculating the topography map.

[0056] In some embodiments, the spatial scaling of an image is based on measurements of known objects to generate an image reference.

[0057] In some embodiments, the image reference is generated by inserting at least one optical element of known width and height, or at least two elements of known spacing, into an objective scanner used to capture an image.

[0058] In some embodiments, the method includes receiving a second set of multiple unmodulated images of an object that does not have an image marker pattern, and applying distortion data from a modulated topography map to the unmodulated topography map to construct a corrected topography map.

[0059] In some embodiments, baseline curvature can be removed from OCT images. Numerical differentiation of the image can be performed to identify the indices of image markers.

[0060] In some embodiments, the phase delay applied to the A-line can be eliminated by shifting the A-line data, or, to obtain more accurate results, by applying a phase shift by applying an index shift on the spectral data equal to the phase shift to the spatial A-line data.

[0061] In some embodiments, A-lines with image markers can be used to correct distortion, but the A-lines themselves can be removed from the image.

[0062] In some embodiments, another image of the same object having a shifted image marker pattern is obtained. At least one image is processed to identify the image markers, and the index data of the marked areas in the image is then replaced with data of the unmarked areas in the other image.

[0063] In some embodiments, accurate spatial scaling of an image can be achieved based on prior knowledge scaling within a portion of the image that has reliable spatial data.

[0064] In some embodiments, accurate spatial scaling of an image can be achieved based on measurements of known objects before or after scanning.

[0065] In some embodiments, accurate spatial scaling of an image can be achieved based on at least two image references, each based on at least one object placed on the objective scanner.

[0066] In some embodiments, the image reference can be realized by inserting an optical element with a known width relative to the objective scanner, or two elements with a known spacing between them.

[0067] In some embodiments, the optical element can be automatically removed from the optical path.

[0068] In some embodiments, a sequence of images is acquired to record at least one image of an object having image markers and references, and an unmarked image of the object. Image analysis of the image markers and references can be applied to provide distortion correction information applicable to the unmarked image.

[0069] In some embodiments, image data can be interpolated based on image marker indices to provide uniform and precise spacing between A-lines or image elements.

[0070] In some embodiments, the final analysis data, such as topographic data, can be interpolated based on an image marker index to obtain accurate topographic information.

[0071] Overview: Quality evaluation of optical surfaces This disclosure relates to an invention that complements an OCT imaging system with a compact pattern-based reflection system in order to examine the quality of an optical surface in detail.

[0072] The reflection of light patterns captured by a camera is an effective means of evaluating corneal topography and tear film breakdown on the corneal surface. This technique for measuring corneal topography requires a relatively large angle between the incident and reflected light rays on the cornea. As the tear film breaks down on the corneal surface, the quality of the reflected light deteriorates, and a correlation can be established between the quality of the tear film and the quality of the captured image.

[0073] STMD provides accurate mapping of the eyeball surface, eliminating the need to use reflection patterns to provide topographic information. Therefore, the difference between the angle of incidence and the angle of reflection can be significantly reduced or eliminated, and the illumination pattern and camera placement allow for comprehensive tear film analysis with a compact system.

[0074] In some embodiments, the imaging system includes an imaging engine; a scanner system including a scanner; a modulator placed after the scanner, which is synchronized with the clock of the imaging engine to generate image markers and starts at a rate that generates image markers; and a pattern-based reflection system coupled to the scanner system via a dichroic combiner, wherein the illumination pattern and the imaging camera are configured with substantially the same optical cone angle.

[0075] In some embodiments, the imaging engine is an OCT system, and the dichroism combiner is located in the OCT imaging path.

[0076] In some embodiments, the pattern-based reflection system further includes a light source that generates a pattern, which is combined with the OCT imaging path.

[0077] In some embodiments, the system includes a camera that images the pattern after it has been reflected from the corneal surface.

[0078] In some embodiments, reflection patterns are recorded to counteract eye movements.

[0079] In some embodiments, the system includes a processor programmed to perform a differential analysis of reflection patterns to analyze the surface of the eyeball.

[0080] In some embodiments, the camera is also used to guide the imaging system to align with the eyeball.

[0081] In some embodiments, the light source is masked using a dichroic beam combiner to merge into the optical path of the objective scanner and generate a pattern. The light is projected onto the surface of the cornea. The reflected light is collected through the same dichroic beam combiner and imaged through a camera.

[0082] In some embodiments, the light source can consist of one or more light sources, preferably light-emitting diodes.

[0083] In some embodiments, a light source can generate a pattern by sequentially illuminating different areas at different times.

[0084] In some embodiments, after recording a reflection image from the corneal surface and correcting for motion, difference analysis can be applied to establish an analysis of the health status of the ocular surface.

[0085] In some embodiments, the same camera can be used to guide an ophthalmic system and align it with the eyeball.

[0086] Overview: Robust biomeasurement using fixation evaluation This disclosure relates to an optical biomedical scanning configuration that provides accurate measurement of axial length at the fovea for all ocular powers of the eye, as well as accurate fixation confirmation simultaneously with biomedical scanning.

[0087] Ophthalmic biometers typically utilize a focused beam of light within the anterior chamber of the eye. Because the numerical aperture of the beam is generally small, the spot size on the retina is not significantly enlarged. However, due to varying variables such as eye length and visual acuity, the spot size on the retina varies considerably from patient to patient. Axial length measurement is optimal for examining the center of the fovea; increasing the spot size would mean measuring the average of a larger area, thus reducing signal intensity and completeness. Both of these factors result in reduced accuracy for the most important parameter of ocular biometrics.

[0088] The beams described above are typically not scanned at all in an A-line biometer, or they are scanned nearly coaxially to cover more of the anterior segment surface. Neither of these configurations is suitable for real-time visualization of the fovea for fixation confirmation or correction. For an eye with a diopter correction of 0, scanning paraxially will always concentrate the scanning beam in the fovea.

[0089] In eyes with diopter correction, the beam is concentrated either posteriorly or anteriorly on the foveal surface, causing the examination spot to scan the fovea across different A-lines, resulting in averaging across a non-uniform region. Similar results occur with other semi-axial scans. During data analysis, the averaging of A-lines can lead to errors due to blurring, or, if only one A-line is used for analysis, it can lead to errors due to noise.

[0090] The optical biosensing beam is preferably scanned within the pupil, or with a rotation center approximately anterior to or posterior to the pupil. For ocular biosensing, it is preferable to focus the beam onto the retina. This configuration provides a clear cross-sectional image of the retina.

[0091] In some embodiments, the ocular biomedical measurement system includes an OCT engine that generates an imaging beam; a scanner that directs the imaging beam towards the eyeball; a focus assembly that focuses the imaging beam onto the retina; a first lens set in the path of the imaging beam that scans with a center of rotation located in the anterior chamber of the eyeball in a plane containing the pupil of the eyeball or a parallel plane immediately before or after the pupil; and an imaging beam that rotates with the center of rotation to image the entire eyeball while simultaneously scanning lines on the retina and cornea of ​​the eyeball.

[0092] In some embodiments, an optical assembly that swirls the imaging beam at a point anterior or posterior to the cornea can be inserted into the path of the imaging beam in order to simultaneously scan the imaging beam across the structure of the cornea and lens.

[0093] In some embodiments, the optical assembly includes an assembly lens and a delay element. In some embodiments, the delay element is selected so as to reduce or eliminate the optical path length difference when the optical assembly is in the path of the imaging beam and when the assembly is out of the path of the imaging beam.

[0094] In some embodiments, the first lens set includes a first telescope and a second telescope, each telescope containing two lenses, and the optical assembly is inserted between the lenses of the second telescope.

[0095] In some embodiments, the system further includes a modulator in the path of the imaging beam after the beam scanner.

[0096] In some embodiments, the ocular biomedical measurement system includes an OCT engine that generates an imaging beam; a scanner that directs the imaging beam towards the eyeball; a first lens in the path of the imaging beam that focuses and scans the imaging beam so that structures within the anterior chamber can be imaged; a second lens that can be inserted into the path of the imaging beam and rotates the imaging beam at a point anterior or posterior to the cornea so that the imaging beam simultaneously scans the structures of the cornea and lens; and when the second lens is in the path of the imaging beam, the beam is nearly focused on the retina, and when the second lens is in the path of the imaging beam, the beam rotates around a center of rotation to image the entire eyeball while simultaneously scanning lines on the retina and cornea of ​​the eyeball.

[0097] In some embodiments, the modulator is placed within the path of the imaging beam.

[0098] In some embodiments, visualization of pits by cross-sectional scanning of the entire eyeball, with the fovea visualized and combined with a camera image of the anterior surface of the eyeball, can be used to identify the optical axis and visual axis of the eyeball, as well as to calculate angular kappa and angular lambda. It can also be used for reliable fixation confirmation and accurate biometric calculation, even in the absence of precise fixation.

[0099] In one embodiment, multiple cross-sectional scans at different locations can be incorporated to generate information regarding volumetric biometric measurements and eye orientation.

[0100] In some embodiments, the optical system within the objective scanner is adjusted to compensate for ocular power and ocular length in order to reliably focus the beam onto the retina.

[0101] In one embodiment, the above adjustments are based on prior knowledge regarding ocular power, visual acuity, or ocular length.

[0102] In some embodiments, focus adjustment is changed during cross-sectional scanning in response to astigmatism or higher-order aberrations.

[0103] In one embodiment, the rotational position of the lens or within the anterior chamber, combined with a scanning area on the retina, is used to calculate the effective lens position.

[0104] In one embodiment, a delay line within the objective scanner or reference arm is used to compensate for the length of the eyeball.

[0105] In some embodiments, speckle analysis is applied to the image to precisely position the scanning rotation center.

[0106] In one embodiment, the preferred scanning geometry is combined simultaneously with or sequentially with another scanning geometry specifically for the anterior segment. [Brief explanation of the drawing]

[0107] The accompanying drawings illustrate exemplary embodiments of the systems and methods disclosed herein and, together with the text, are used to illustrate the principles of this disclosure.

[0108] [Figure 1] Figure 1 shows an example of a system embodiment for performing optical coherence tomography for the purpose of accurately mapping the surface of an object by incorporating a spatiotemporal modulation / demodulation (STMD) method.

[0109] [Figure 2] Figure 2 is a sketch representing an anterior segment OCT image showing STMD modulation as z-modulation.

[0110] [Figure 3] Figure 3 is a timing diagram for achieving this type of modulation using swept-source OCT (SSOCT).

[0111] [Figure 4] Figure 4 shows an example of an optical setup for achieving z-modulation using a high-speed optical delay line assembly.

[0112] [Figure 5] Figure 5 shows an STMD-based OCT system with two candidate modulator placements: one conjugate to the scanner and the other near the scanner.

[0113] [Figure 6] Figure 6 is a sketch representing an anterior segment OCT image showing STMD modulation as i-modulation.

[0114] [Figure 7a] Figure 7a shows the system from Figure 1, but with the object being imaged being an eyeball. The optical system scans the beam over the eyeball almost paraxially. The modulator is positioned almost conjugate-plane to the scanner.

[0115] [Figure 7b] Figure 7b shows the system of Figure 1, but with the object being imaged being the eyeball. The optical system scans the beam over the eyeball almost paraxially in the anterior segment. The modulator is located near the scanner.

[0116] [Figure 7c] Figure 7c shows the system of Figure 1, where the object to be imaged is the eyeball. The optical system scans the beam over the eyeball almost paraxially over the anterior segment. The large-area modulator is installed in free space within the telescope assembly.

[0117] [Figure 8a] Figure 8a shows a system similar to Figure 7b, but modified so that the beam scans to concentrate on the anterior segment and then almost swirls around the pupillary plane to scan the posterior segment. The modulator is located near the scanner.

[0118] [Figure 8b]Figure 8b shows a system that can, in some cases, scan the eyeball using a nearly parallel beam in the anterior segment, and can switch to a beam that nearly swirls within the pupil to scan the posterior segment. The difference in optical delay between the anterior and posterior segments in each of the two modes is minimized. The modulator is mounted on the conjugate plane of the scanner.

[0119] [Figure 8c] Figure 8c shows a system that can, in some cases, scan the eyeball using a nearly parallel beam in the anterior segment and switch to a nearly swirling beam within the pupil to scan the posterior segment. The difference in optical delay between the anterior and posterior segments in each of the two modes is minimized. The modulator is placed after the last target in the paraxial scanning mode and removed from the optical path in the pupillary swirling scanning mode.

[0120] [Figure 9] Figure 9 shows a simplified scanning optical setup that can be used for single-pixel imaging of an object.

[0121] [Figure 10] Figure 10 shows an example workflow for an algorithm that reconstructs spatially corrected information from an image with z-modulation.

[0122] [Figure 11] Figure 11 shows an example workflow for an algorithm that reconstructs spatially corrected information from an image with i-modulation.

[0123] [Figure 12] Figure 12 illustrates the main steps of an algorithm for reconstructing spatially corrected information from an image with z-modulation, as shown in Figure 10.

[0124] [Figure 13] Figure 13 shows an STMD-based OCT system with a reflection-based imaging system that projects images onto the corneal surface to examine the health of the eyeball surface.

[0125] [Figure 14] Figure 14 shows a setup using portable devices to examine the health of the eye surface.

[0126] [Figure 15] Figure 15 shows a scanning pattern that is preferred for optical biosensors, in which the beam is almost focused on the retina and scans mainly the pupillary plane while the OCT is imaging along the entire eyeball.

[0127] [Figure 16] Figure 16 shows preferred scanning patterns for optic biosensors, one example where the beam is nearly focused on the retina and scans around the pupillary plane while the OCT images along the entire eyeball, and another example where the beam is nearly focused on the anterior segment and scans along the anterior segment while the OCT images along a portion or the entire eye.

[0128] [Figure 17a] Figures 17a and 17b show, in one example, an arrangement that scans the eyeball paraxially, and in another example, an arrangement that scans within the pupillary plane with a swirling beam. Switching is achieved by removing the optical system from the optical path, taking into account a specific difference in optical path length between the two states. [Figure 17b] Figures 17a and 17b show, in one example, an arrangement that scans the eyeball paraxially, and in another example, an arrangement that scans within the pupillary plane with a swirling beam. Switching is achieved by removing the optical system from the optical path, taking into account a specific difference in optical path length between the two states.

[0129] [Figure 17c] Figures 17c and 17d show, in one example, an arrangement that scans the eyeball paraxially, and in the other example, an arrangement that scans within the pupillary plane with a swirling beam. Switching is achieved by removing the optical system from the optical path, which has the ability to move the optical setup to adjust to a specific optical path length difference between the two states. [Figure 17d]Figures 17c and 17d show, in one example, an arrangement that scans the eyeball paraxially, and in the other example, an arrangement that scans within the pupillary plane with a swirling beam. Switching is achieved by removing the optical system from the optical path, which has the ability to move the optical setup to adjust to a specific optical path length difference between the two states.

[0130] [Figure 18a] Figure 18a shows an example of an OCT image of the anterior segment of the eyeball with a reference mark placed outside the region of interest.

[0131] [Figure 18b] Figure 18b shows the ring mechanism, which is part of the element.

[0132] [Figure 18c] Figure 18c shows a ring mechanism, which is the part of the optical element that is bonded, mounted, or installed near the modulator.

[0133] [Figure 18d] Figure 18d shows the four-point mechanism, which is the optical element.

[0134] [Figure 18e] Figure 18e shows an optical fiber attached to an optical element adjacent to the modulator. [Modes for carrying out the invention]

[0135] For the purpose of facilitating understanding of the principles of this disclosure, embodiments shown in the drawings are described here in a specific language. Nevertheless, it will be understood that this does not limit the scope of this disclosure. Any changes and further modifications to the systems, apparatus, fixtures, and methods described, as well as any further applications of the principles of this disclosure, are given full consideration as would be expected of a person skilled in the art to which this disclosure relates. In particular, features, components, and / or steps described in relation to one embodiment may be combined with features, components, and / or steps described in relation to other embodiments of this disclosure. For simplification, in some examples, the same reference numeral is used throughout the drawings to indicate the same or similar parts.

[0136] Figure 1 shows an example of a system that encodes modulation into two-dimensional or three-dimensional OCT images for the purpose of accurately correcting static and dynamic distortions. The A-line scanner 100 directs light onto the object or tissue to be examined through the optical system of the objective scanner 101. OCT imaging can be performed on surfaces or aggregate surfaces such as precision components like optical surfaces. For example, posterior segment imaging for examining the retina and / or anterior segment imaging for examining the lens and / or cornea can also be performed.

[0137] Figure 1 shows a system for performing accurate three-dimensional mapping of OCT data using STMD. The A-line scanner 100 includes a light source 102, an interferometer 104, a reference arm 103, a detector 105, a processor 106, and a display 107. Sample light from the interferometer is directed to the objective scanner 101, and a set of optical components scans the light beam in the horizontal and vertical dimensions of the object 110. The light enters the objective scanner 101 through the waveguide 120 and optical component 121, forming a beam, typically a parallel beam 126. The beam is scanned by the scanner (or scanning mechanism) 122 over the maximum angular range indicated by the peripheral rays 127. A telescope consisting of lenses 123 and 124, in the case of swept-source OCT, images the component surface to be scanned on a modulator 128 synchronized with the light source 102 via a connector 129. The light beam is finally scanned over the object 110 via the objective lens 125. The distance between lens 123 and lens 124 can be changed to adjust the concentration or divergence of the beam over the object 110.

[0138] In one example, a high-speed modulator 128 is incorporated after the scanner (or scanning mechanism) 122 to achieve the modulation required for STMD. The modulator 128 marks one or more A lines out of every N A lines, in conjunction with the A-line trigger and timing. If the modulator 128 can impose a large phase shift in the z direction, the modulation is observed as a z-shifted A line, as shown in Figure 2. This shift 201 is called z-modulation. Because the modulation is performed at constant time intervals, while the scanner is not moving at a constant speed, the spacing between image markers can be used to compensate for distortion caused by the nonlinearity of the lateral scan, resulting in distortion-free images and measurements. In one example, the z-shift is equal to at least one pixel so that the image processing algorithm can detect the position of the modulated A line. Image modulation can be removed to produce a clean image. Z-modulation can be reversed by reversing the shift amount in the digital domain.

[0139] Figure 2 shows a depiction of an OCT cross-sectional image of the anterior part of the eyeball, showing the anterior cornea 202, posterior cornea 203, anterior lens 204, posterior lens 205, and iris 206. In the example in Figure 2, the A line is shown, which has been phase-shifted by z-modulation. Marker 201 can be used to correct for nonlinearity and inaccuracies of the scanning mechanism.

[0140] Figure 3 shows one example of a timing scheme for applying modulation to a single A-line. To achieve this modulation, modulator 128 is driven by a step function 303, which applies a delay to a specific A-line. In this case, the response time of modulator 128 is sufficient to perform the subsequent transition between A-lines. Most swept-source (SS) OCT lasers operate with a duty cycle of approximately 70%, and switching can occur during a 30% off-time. 301 indicates the ID number of the A-line. 302 shows the laser sweep profile versus time. 303 shows the modulation command with a solid line and the modulator's time response with a dotted line.

[0141] The modulation interval represents the total number of A lines per period (modulated A lines + unmodulated A lines). The modulation duty cycle represents the ratio of modulated A lines to the interval. In this example, two conditions are met to detect distortion of position on the image. The first condition is that the interval is sufficiently small to provide sufficient sampling of scanning dynamics, which means the interval is smaller than the total number of A lines per scan. The second condition is that the duty cycle is sufficiently larger than 1 / 2 to avoid averaging during modulation. Experiments have shown that the best results are obtained when modulation on an OCT image is represented by a single modulated A line at a time. Since the interval between modulated A lines represented by a single A line does not provide recoverable information about the lateral velocity of the scan, a duty cycle of 1 / 2 does not transmit distortion information.

[0142] Experiments have shown that a direct phase modulation technique using lithium niobate crystals is stable and reproducible. In this example, the implementation with lithium niobate crystals is limited to small aperture sizes, and the polarization dependence of the shift is not considered.

[0143] In another example, phase modulation using an acousto-optic (AO) crystal is a viable method for producing z-modulation. In this case, the first-order diffracted beam is selected from the AO phase shifter at a modulation frequency f0 sufficient to separate the first-order diffraction from the zero-order diffraction. Since the depth information of the OCT is modulated based on frequency, applying this constant frequency shift will result in the zero-delay position coinciding with f0 rather than f=0. N f is the Nyquist frequency for analog-to-digital conversion. N If equal to / 2, the zero delay position will be in the center of the imaging range. To achieve frequency shift, the modulation frequency of the first-order diffraction can be changed to f0 + δf for the period during which the A line is shifted. Baseline frequency modulation can be maintained if necessary. If not necessary, f0 modulation can be removed and limited to δf by demodulating during the A line reconstruction process or by installing another AO modulator on either the sample arm or the reference arm.

[0144] Figure 4 shows an example of an alternative modulation scheme that can be realized by placing mirrors on a piezoelectric device (mechanism 407) in the optical path to achieve the desired modulation parameters. In this example, the A-line scanner 100 (also called the OCT engine) illuminates the optical setup via a collimator 401. The beam is scanned over the object 408 via the scanner mechanism 405 and lenses 402, 403, and 404. Mechanism 407 consists of a foldable reflector setup mounted on a piezoelectric actuator that operates to modulate the A-line. The modulation is synchronized with the A-line sweep via an A-line trigger 406.

[0145] It is also possible to perform intensity modulation (i-modulation) instead of phase modulation. The advantage of this method is that intensity modulation is easier to implement. Intensity modulators operate at high speed, and modulation can be applied to a single A-line without affecting preceding or succeeding A-lines. An example of an intensity modulator is a solid-state modulator such as an AO operating in intensity modulation mode. In this example, the absence of content in the modulated A-line can help identify and correct positional errors in the scanner, as shown in Figure 6, for example. The information in the modulated A-line cannot be reconstructed from the same image. This effect can be addressed through one of two methods. The first method is to record two subsequent scans by repeating the same scanning pattern. One scan is i-modulated, and the other is not. By applying the distortion information calculated based on the modulated scan to the second scan, a distortion-free image or map can be created. The second method is applicable to topography applications where multidimensional surfaces are fitted to segmented OCT surfaces, and the sparse absence of data points corresponding to blank A-lines may not be deemed to affect the results.

[0146] In another example, intensity modulation can be performed by incorporating an intensity modulator into the optical path. Figure 5 shows a setup in which an OCT engine or A-line scanner 100 illuminates the optical setup via a collimator 501. The beam is scanned over the object 509 via a scanner mechanism 502 and lenses 503, 504, and 505. In this example, only one of the two modulators 506 or 507 shown in the figure is required. The modulation performed by modulators 506, 507 is synchronized with the A-line sweep via an A-line trigger 508. In one example, modulator 507 is placed between scanner 502 and lens 503. In this example, modulator 507 is coupled to the OCT engine 100 via the A-line trigger 508. In another example, modulator 506 is placed between lens 504 and lens 505. In this example, modulator 506 is coupled to the OCT engine 100 via the A-line trigger 508.

[0147] In one exemplary embodiment, intensity modulation can be performed by means of inserting an AO modulator into the optical path at either position 506 or 507, or simply by operating a mirror between A lines to blur the contents of the mirror (in the case of SSOCT) or to blank the mirror by washing spectral fringes (in the case of spectral domain OCT), as described in the dynamic optical delay of Figure 4. The step response requirement for the dynamic optical delay in this case is considerably lower than that required for z modulation. For example, a modulation amplitude of π-2π is sufficient, and the rise and fall times are faster. In this example, the technique operates in two modes: z modulation at a low OCT speed and i modulation at a high speed.

[0148] Figure 6 shows an example in which the i-modulation marker 601 is created by intensity modulation rather than phase modulation. The marker 601 can be placed on each imaging plane.

[0149] Figure 7a shows the same setup as in Figure 1, where the scanned object is the eyeball 701, any part of the eyeball 701, or a fragment of the eyeball 701.

[0150] Figure 7b shows a different placement of the modulator 701 in proximity to the scanning component, with the same configuration as in Figures 1 and 7a. In this example, the modulator 701 is placed in close proximity to the scanner (or scanning mechanism) 122. This placement of the modulator 701 allows for greater flexibility in the downstream optical design. For example, lenses 125, 124, and 123 can be removed. In this example, the modulator 701 has a wider reception angle and a larger aperture than the modulator 128 in the setup of Figure 7a.

[0151] Figure 7c shows a different placement of modulator 702 between lenses 123 and 124, with the same configuration as Figures 7a and 7b. In this example, modulator 702 is a wide-area modulator. This placement of modulator 702 allows for greater flexibility in the downstream optical design. For example, lenses 125 and 124 can be removed. The configuration in this example reduces the requirements for the modulator's reception angle. Large-area modulators, such as liquid crystal modulators, generally have slow response times, but this is sufficient for the purposes here.

[0152] Figure 8a shows an example configuration that enables OCT imaging of the posterior part of the eyeball 701. The example in Figure 8a is similar to the example in Figure 7b. In this example, the OCT engine or A-line scanner 100 illuminates the scanning mechanism (or scanner) 122 via the collimator 121. The modulator 702 is positioned proximal to the scanning mechanism (or scanner) 122. A telescope, consisting of lenses 123 and 124, swirls the beam approximately around the pupillary plane of the eyeball (the plane located in the anterior chamber of the eyeball that contains the pupil). The distance between lenses 123 and 124 can be changed to focus on retinal tissue. The example in Figure 8a is suitable for imaging posterior segment structures such as the retina and retinal layers, as well as objects or structures within the posterior part of the eyeball.

[0153] Figure 8b shows an example configuration in which the OCT engine or A-line scanner 100 illuminates the modulator 128 via a telescope comprising a collimator 121, a scanning mechanism (or scanner) 122, and lenses 123 and 124. The modulated light beam then scans the posterior part of the eyeball 701 via lenses 125 and 801, or the anterior part of the eyeball by adding lens 802. In this example, lens 802 is a movable objective lens that allows the optical setup to scan either the anterior part of the eyeball (when lens 802 is out of the optical path) or the posterior part of the eyeball (when lens 802 is in the optical path). In another example, lens 802 is in the optical path when imaging the anterior segment and out of the optical path when imaging the anterior segment. This configuration provides flexibility in switching between anterior and posterior segment scanning and reduces the aperture requirement of the modulator 128, enabling faster scanning.

[0154] Figure 8c shows an example configuration in which the OCT engine or A-line scanner 100 illuminates the modulator 804 via the collimator 121, scanning mechanism 122, and lenses 123, 124, 125, 801, and 802. In this example, the modulated light beam directly scans the anterior portion of the eyeball 701. Since the modulator 804 is installed as the last optical element of the system, this configuration provides the ability to compensate for distortions in all static and dynamic systems within the system. To scan the posterior portion of the eye, both the lens 802 and the modulator 804 are removed from the optical path. In this case, STMD is not applied to scanning the posterior portion of the eyeball. In this example, the modulator 804 is incorporated into an assembly that includes the lens 802.

[0155] Figure 9 shows an example of a scanning mechanism and an imaging engine 900. In this example, the imaging engine 900 may be an OCT or another technology, such as a single-pixel camera. With respect to a single-pixel camera-based imaging system, a portion of the object 901 is imaged by a lens 902 on the scanning mechanism 905 via a modulator 904. The beam then propagates to the camera 900. To image another portion of the object, the scanning mechanism is moved to collect light from that portion. As the scanning mechanism 905 continues to move, multiple image points are collected to generate an image. The angular range of the scanned beam is shown as 903. The modulator 904 is synchronized to the imaging engine 900 via line 907 and started to generate i-modulation on the image. Modulation is used to correct image distortion.

[0156] Figure 10 shows an example of a method for modulated images or topography. The input to this method is an STMD image in which z-modulation preserves distortion information, and the output is a distortion-free image. The modulated image 1001 is processed in 1002 to remove baseline curvature if necessary, for example, to make the anterior surface of the cornea nearly flat. The derivative applied in 1003 is taken along the horizontal direction of one or more surfaces. The results of the derivative are used in 1004 and 1006 to identify the start index 1005 and end index 1007 of the modulated event.

[0157] Z-modulation is removed at 1008, and the indices calculated at 1005 and 1007 define the first and last A-lines that are shifted over a given interval. The shift is applied by applying a sub-pixel phase shift to the z-modulated A-lines. The shift can be achieved by oversampling or by offsetting the wavelength index to process the spectral A-lines. This results in an accurate phase shift of the A-lines. The offset amount can be pre-calculated based on prior knowledge of the system or based on minimizing the difference between pixels.

[0158] If the objective is to remove distortion caused by the scanning mechanism from individual images, for example, a B scan, then an interpolation step is applied to image 1009 in 1010, and the horizontal dimensions are rescaled according to the indices 1005 and 1007. The output is a corrected image 1011 without scanning distortion.

[0159] For example, if the objective is to remove distortion caused by the scanning mechanism from a large amount of data, such as a topography map, the topography is calculated from multiple images 1009. Next, in 1013, the topography is corrected by interpolating the three-dimensional information according to the indices 1005 and 1007. The output is a corrected topography 1014 free from scanning distortion.

[0160] Figure 11 shows an example of how to process a modulated image or topography. The input to the algorithm is an STMD image in which the modulation preserves distortion information, and the output is a distorted image. The modulated image 1101 is processed in 1102 to remove baseline curvature if necessary, for example, to make the anterior surface of the cornea nearly flat. The derivative applied in 1103 is taken along the horizontal direction of one or more surfaces. The results of the derivative are used in 1104 and 1106 to identify the start index 1105 and end index 1107 of the modulation event.

[0161] i-modulation is removed in 1108, and the indices calculated in 1105 and 1107 define the first and last A-lines which are replaced within a predetermined interval by A-lines from the unmodulated image 1109 acquired following image 1101.

[0162] If the objective is to remove distortion caused by the scanning mechanism from individual images, for example, from a B scan, an interpolation step is applied to image 1109 in 1110, and the horizontal dimensions are rescaled according to the indices 1105 and 1107. The output is a corrected image 1111 without scanning distortion.

[0163] For example, if the objective is to remove distortion caused by the scanning mechanism from a large amount of data, such as a topography map, the topography is calculated from multiple images 1109. Next, in 1113, the topography is corrected by interpolating the three-dimensional information according to the indices 1105 and 1107. The output is a corrected topography 1114 free from scanning distortion.

[0164] Figure 12 shows an example of steps taken to remove modulation and distortion from an anterior segment OCT image. Most of the curvature of the anterior corneal surface in z-modulated image 1201 is removed in step 1202. Step 1202 can be done by removing the average corneal curvature, or by detecting the curvature in the anterior surface of this particular image after smoothing the surface, and then shifting the A-line according to that curvature information. Image 1203 is the image after removing the curvature of 1201, and is the same as 1201. The envelope 1204 shows that the anterior corneal surface is precisely separated from the rest of the image. In step 1205, a horizontal derivative is applied to the envelope portion of image 1204. The result of the derivative is shown in 1206, where the negative and positive spikes correspond to the start and end of each modulation event, respectively. In step 1207, negative spikes are removed by eliminating all values ​​below the horizontal line in order to select only the positive spikes as shown in 1208. In step 1209, the spike index is identified, and in step 1210, the index vector is stored. In step 1211, the index is applied to remove z-modulation, interpolate the image to remove distortion, and generate a corrected image 1212.

[0165] The 1212 image is distortion-corrected for all lateral distortions introduced before the modulator used to modulate the image. This includes static distortion from the optical system, as well as static and dynamic distortion from the scanning mechanism. Static distortion from the optical system downstream of the modulator and fan distortion can be excluded from calibration. In this example, the surface used for distortion correction, i.e., the anterior surface of the cornea in the example of Figure 12, is used as the reference point when other distortion corrections are applied.

[0166] Proper lateral scaling of STMD-corrected images can be achieved by calibrating the image using known targets. Since scanning mechanisms typically exhibit a non-linear response with respect to speed, different scanning patterns may require different scaling. To ensure accurate scaling regardless of the scanning pattern, spatial reference marks can be incorporated into the image. As mentioned earlier, since image distortion is removed, two points are sufficient to accurately scale the image. This is done by adding markers representing additional image references based on physical features with precise dimensions. These markers can be used to provide a reference for accurate scaling.

[0167] In an OCT system, a reference can be generated by imaging two optical objects within the sample arm, interfering their signals with the reference arm. To achieve this, the optical path length of the reference must be matched to that of the reference arm, either by shortening the reference arm or by extending the optical path toward the reference within the sample path.

[0168] To ensure that the reference does not interfere with the image, the reference must be inserted outside the image's field of view, and the scanner's scanning range must be widened before, after, or during the imaging process. Alternatively, the reference can be placed in a setup that allows it to be activated to insert into or remove from the optical path.

[0169] Reference markers can be specular reflectors or scatterers. Scatterers are particularly desirable for operational references because they require less adjustment.

[0170] Alternatively, the reference marker can be incorporated into the modulator by switching, laser marking, or simply imaging the edge of the modulator.

[0171] Thin, cylindrical objects such as optical fibers can be used as reference markers. Because the fiber is thin, it is easy to generate an autocorrelation signal within the optical fiber, which can be easily confirmed on OCT images. Since the autocorrelation of the sample path does not require interference with light from the reference arm, this method eliminates the need to adjust the optical path length between the sample arm and the reference arm. These mechanisms can be visualized near zero delay through a depth proportional to the optical path between correlated mechanisms within the sample arm.

[0172] Figure 18a shows an example of an OCT image of the anterior segment layer of the eyeball 1801 with a reference mark 1800 placed outside the region of interest 1802.

[0173] In swept-source OCT, autocorrelation is usually suppressed by equilibrium detection. However, this suppression is limited to about 30 dB. In this case, the autocorrelation cannot be visualized unless the autocorrelation strength exceeds the suppression by equilibrium detection.

[0174] The function of generating an autocorrelation criterion can also be generated by creating the function within the modulator itself or within an optical element that can be bonded to the modulator. For example, by changing the refractive index of the optical medium bonded to the modulator, a ring consisting of two surfaces spaced approximately 0.25 mm apart can be created. Alternatively, a ring consisting of cloud-like scatterers can be used. The ring mechanism should be drawn outside the imaging field of view if the mechanism is stationary in the optical path. If the mechanism is removable from the optical path, it can be within the field of view.

[0175] Figure 18b shows an example where the ring mechanism 1804 is part of element 1803, and this element can be the modulator itself or a separate optical element.

[0176] Figure 18c shows an example where the ring mechanism 1804 is part of the optical element 1805 that is bonded, attached, or installed near the modulator 1806.

[0177] In another example, a four-point mechanism mark can be used instead of a ring. The mark should be placed outside the imaging field of view if the mechanism is stationary in the optical path. If the mechanism is removable from the optical path, it can be placed within the field of view.

[0178] Figure 18d shows an example where the four-point mechanism 1807 is a portion of the optical element 1805 that is bonded, mounted, or installed near the modulator 1806.

[0179] Figure 18e shows an example in which a mechanism consisting of optical fibers 1808 is attached to an optical element 1805 which is joined, mounted, or installed near a modulator 1806. The fiber is attached to the optical element 1805 via a support 1809 that does not obstruct the B scanning field, and at least four points of the fiber are exposed for optical inspection. Biomedical measurements and topography for quality evaluation of optical surfaces

[0180] Figure 13 shows an example of an OCT-based STMD system, similar to the systems shown in Figures 1, 7a, and 8a, used for accurate mapping of the ocular surface, combined with a compact reflective base configuration to assess the health of the corneal surface and tear film. In this setup, the STMD allows OCT to provide accurate topographic maps of the corneal and lens surfaces. The topographic maps represent the shape of specific surfaces, such as the anterior corneal surface, including sphericity, toricity, and higher-order aberrations. The reflective base configuration in Figure 13 provides information about tear film health because the reflection of light from the anterior cornea is more sensitive to tear film disturbances than OCT. Since the reflective base configuration does not extract topographic information, it does not require a large angle between the illumination light and the imaging light on the cornea, as is the case with Placido topographs, and the system can be built in a compact setup.

[0181] The arrangement in Figure 13 consists of generating a pattern 1302 with dark and bright regions. The illumination beam 1304 from the pattern passes through a beam splitter 1306 and is then incident on the OCT path via a dichroism combiner 1301. The pattern is then projected onto the anterior surface of the cornea, and the image of the pattern on the cornea is returned outside the OCT path via 1301. The collected beam is directed via 1306 to capture a beam 1305 on camera 1303. The illumination pattern 1302 can consist of properties that are a function of time as well as space, or a combination of time and space.

[0182] The reflection-based patterns available in this configuration can consist of concentric rings, arrays of spots, or grids of lines. Other patterns or shapes may also be used. Temporal modulation can be used to avoid aliasing of discrete spots on the cornea.

[0183] Figure 14 shows a setup utilizing a mobile device with time-modulated illumination spots to evaluate corneal topography and tear film resolution characteristics. The mobile phone hardware for facial recognition and LiDAR includes an array of illumination spots imaged using a camera system adjacent to the illumination array. Distortion of the illumination pattern is converted into a three-dimensional map. The illumination area and field of view of the mobile phone's (or iPhone®) inherent optical system are quite wide, and the resolution is on the order of 1 mm, which is insufficient to monitor the corneal surface. As shown in Figure 14, an optical imaging system 1402 is inserted between the mobile device 1401 and the eyeball 1404 to increase the spot density on the eyeball 1404. System 1402 projects divergent rays of illumination pattern 1403 onto the eyeball and re-images the eyeball with a camera to reconstruct a high-resolution topographic map. Due to the sensitivity of infrared reflection to tear film quality, and because video data is recorded by the camera, differential time analysis can be applied for the analysis of tear film resolution. Robust biometric measurement

[0184] Today's optical biometric measurement devices continue to have limitations in measurement, regardless of refractive error, amblyopia, presbyopia, or emmetropia. Because there is no robust indicator of fixation accuracy during measurement, the accuracy of the results heavily depends on the patient's fixation. For example, the IOL Master 700 (Carl Zeiss Meditec) has a fixation confirmation function that is not performed simultaneously with data acquisition. A-scanning biometers measure axial length (AL) by illuminating the cornea with a fixed, nearly parallel beam of light. A-scanning biometers depend on the patient's eye position relative to the fixed position of the biometer to perform axial length measurement at the fovea. This method works effectively only in properly fixed, emmetropic eyes where the light beam is focused on the foveal surface. In refractive error, amblyopia, and presbyopia, where the light beam is spread to cover a wide area of ​​the fovea, the axial retinal signal becomes blurred, making accurate reading of refractive error, amblyopia, and presbyopia difficult. B-scanning biometers utilize the same concept, differing only in that they use a scanned beam rather than a fixed beam on the cornea. B-scanning biometers suffer from the same beam focusing challenges that A-scanning biometers face in refractive amblyopia and presbyopia. Furthermore, because the beam scanned paraxially over the anterior segment converges, all beams revolve around the fovea of ​​an emmetropic and fixed eyeball. In refractive amblyopia and presbyopia, the center of rotation shifts anteriorly or posteriorly to the foveal surface, causing further blurring when calculating AL using information from all beams.

[0185] To overcome issues of focus, blurring, and fixation confirmation, Figure 15 shows a setup of a scanning pattern applied to the entire eyeball to simultaneously generate accurate biometric information and fixation confirmation. The beam 1503 is approximately swirled in the pupillary plane of the anterior segment 1501. In this case, the pupillary plane is the plane in the anterior chamber of the eyeball containing the pupil. The pupillary center can be determined (e.g., by camera imaging) and used as the center of rotation. The peripheral ray 1504 traverses a region on the retina 1502 while capturing biometric information. As a result, the fovea 1505 can be clearly resolved in the image. The beam enters the cornea with a wavefront preset to generate an approximate focal point on the RPE (retinal pigment epithelium) plane of the retina.

[0186] To enable this, the optical setup on the OCT system's sample arm allows the eye to be illuminated with a focused scanning beam and the center of rotation to be positioned around or behind the pupillary plane. In this example, the focused beam on the OCT system's sample arm is focused on a center of rotation that may be at the pupillary center, within the pupillary plane, or slightly in front of or behind the pupillary plane.

[0187] This setup further includes a focusing optical system that is adjusted to reliably focus the beam onto the retina in any eye, regardless of whether it has refractive errors, amblyopia, presbyopia, or normal vision.

[0188] This setup allows for simultaneous visualization of all eye surfaces necessary for biometric measurements. Lateral resolution defects in the anterior segment do not affect the accuracy of basic measurements of axial length (AL), anterior chamber depth (ACD), and lens thickness (T). The beam is focused on the retina and traverses the retinal surface, improving consistency and accuracy when determining axial length at the fovea. It also provides information about eye fixation within the same image, allowing for simultaneous confirmation of fixation. Furthermore, important biometric measurements (AL, ACD, T) can be obtained even from unfixed eyes.

[0189] The configuration in Figure 15 provides the ability to focus the beam to the fovea and scan along the fovea. This offers the advantages of precise foveal distance measurement and clear visualization for evaluating fixation. However, this configuration compromises the detailed field of view of the anterior segment. Figure 16 shows the same system as in Figure 15, but complemented by another scanning configuration 1601 that is approximately paraxial with the approximate focal plane in the anterior chamber. In the example in Figure 16, the center of rotation is moved away from the pupil to enable scanning of the cornea, lens, iris, and anterior chamber. Adding paraxial scanning allows for obtaining high-resolution images of the anterior segment that can be registered in images recorded using the swirling scanning pattern. By registering two images or volumes, a high-resolution overall view of the ocular surface can be obtained in both the anterior and posterior segments without compromising the accuracy of the biometric measurements obtained using swirling scanning.

[0190] Figure 17 shows the configuration for realizing the scanning patterns described in Figures 15 and 16. Figure 17a shows the configuration for paraxial scanning of the eyeball. The OCT engine or A-line scanner 100 illuminates the collimator 1701 via the waveguide 1700. The parallel beam 1703 is scanned using the scanning mechanism 1702. The scanned beam 1704 is imaged using lenses 1705 and 1706. A phase modulator or amplitude modulator 1707 is mounted in the image plane of the scanner. The modulator is synchronized with the master trigger 100 via the trigger line 1708. The scanned beam further propagates through an optical system consisting of lens 1709, delay element 1712, and lenses 1710 and 1711 to illuminate the eyeball 1714 with the paraxially scanned beam. The assembly 1713, consisting of lens 1710 and delay element 1712, is mounted on the movable mechanism.

[0191] Figure 17b shows the same configuration as in Figure 17a, where assembly 1713 is moved outside the usable optical aperture. This results in a swirling scan on the eyeball, which is used to achieve the biomechanical scanning shown in Figures 15 and 16.

[0192] The optical delay element 1712 eliminates or reduces the difference in optical path length between the arrangements in Figures 17a and 17b. The delay element 1712 can simply be a glass cube. Preferably, the delay element 1712 is composed of an element with an adjustable delay to account for different eyeball lengths. This can be achieved by utilizing the tilt of the optical cube to adjust the delay, or by using a movable wedge to adjust the optical delay encountered by the beam. This preferred configuration allows switching between two imaging modes with the same optical path delay.

[0193] As mentioned earlier, optical focusing or blurring may occur as the beam propagates through the eyeball. This can be corrected by changing the magnification of the telescope consisting of lenses 1705 and 1706, lenses 1706 and 1709, or lenses 1709 and 1711. Any of these adjustments require adjustment of the scanning mechanism's drive signal to maintain the lateral imaging range.

[0194] Figures 17c and 17d show two configurations of alternative arrangements that can be employed to achieve orbital and paraxial scanning of the eyeball. Figure 17c shows how the OCT engine or A-line scanner 100 illuminates the scanning mechanism 1702 with a parallel beam propagating through the collimator 1701 and waveguide 1700. The scanned beam 1704 is modulated by a modulator 1707, which is synchronized with the trigger of the OCT engine or A-line scanner 100 via 1708. A telescope, consisting of lenses 1705 and 1706, translates the beam across the rear of the eyeball 1714. The telescope is also used to achieve a desired focus on the retina. Lens 1706 is mounted on a mechanism that is removable or inserted relative to the optical path. Assembly 1715 is axially movable.

[0195] Figure 17d shows the configuration in Figure 17c, where lens 1706 is removed from the optical path to achieve paraxial scanning over the eyeball. Assembly 1715 is moved to adjust the optical path length of the sample arm. Additional optical delays, such as the delay element 1712 in Figures 17a and 17b which works in conjunction with lens 1706, can also be employed in this configuration.

Claims

1. A system for providing accurate lateral mapping of images acquired via a scanning mechanism, An imaging engine that outputs a light beam and an imaging engine clock, A scanner system including a scanner, configured to direct / deflect the light beam toward an object via an optical path, A modulator placed on or after the scanner, which, in order to generate an image marker, adjusts the light beam along the optical path from the scanner system to the object in accordance with the imaging engine clock and starts up at a speed that generates the image marker on the image element, A system comprising at least one processor configured to receive signals from the imaging engine, process the signals to form image elements with image markers, and generate a corrected image based on the image elements and the image markers.

2. The aforementioned imaging engine, Light source and Beam splitter and combiner configuration, Reference placement and, Sample scanning arrangement, Detector and The system according to claim 1, comprising an OCT scanner consisting of the following.

3. The system according to claim 1, wherein the imaging engine comprises a single-pixel camera or detector.

4. The system according to claim 1, wherein the imaging engine comprises a line scanning camera.

5. The system according to claim 1, wherein the imaging engine comprises a LiDAR system.

6. The system according to claim 1, wherein the modulator is positioned after all optical components of the optical system after the scanner to eliminate the need to calibrate the mechanical drift of the scanner and the optical distortion of the optical components.

7. The system according to claim 1, wherein the modulator is an active modulator selected as individual elements or combinations from the group consisting of an acousto-optic modulator, a liquid crystal modulator, an electro-optic modulator, a piezoelectric element, a galvanometer scanner, and a voice coil.

8. The system according to claim 1, wherein the modulator is a passive modulator selected as individual elements or combinations that incorporate spatial characteristics that cause a phase, intensity, or other shift for one or more imaging events.

9. The system according to claim 1, wherein the modulator causes a change in image characteristics applied to at least one image element, and the change to the image element includes one or more groups consisting of amplitude change, phase change, color change, speckle and / or speckle change.

10. The system according to claim 1, wherein at least one processor is configured for the purpose of providing an IOL calculator or mapping of the surface of the eyeball for planning cataract surgery and refractive surgery.

11. A system for providing accurate lateral mapping of images acquired via a scanning mechanism, An imaging engine that outputs a light beam and an imaging engine clock, A scanner system including a scanner, configured to direct / deflect the light beam toward an object via an optical path, A method for generating a reference that can be used to calibrate a corrected image to precise spatial dimensions, Equipped with, A system in which the at least one optical object is selected from the group consisting of optical fibers, cylindrical objects, specular reflectors, and scatterers.

12. The system according to claim 11, wherein the optical object is integrated with a modulator.

13. The system according to claim 11, wherein the reference optical path length matches the optical path length of the reference arm of the imaging engine.

14. The system according to claim 11, wherein the criterion is generated by optical interaction within the optical object without interference with the reference arm of the imaging engine.

15. The system according to claim 11, wherein the aforementioned criteria are outside the domain of interest.

Images