An apparatus includes a schlieren imaging assembly and a processor. The schlieren imaging assembly includes one or more two-dimensional (2D) schlieren imaging systems and is configured to acquire two-dimensional (2D) schlieren images of turbulence occurring in fluid media from a plurality of viewing angles. The processor is configured to produce, from the 2D schlieren images, a time-series of three-dimensional (3D) schlieren images corresponding to respective time instances.

A digital projection and reflected glare reduction system according to various aspects of the present technology may include a digital display device capable of generating a one or two dimensional source grid pattern back-illuminated by a light source to project an image of a source grid onto a retroreflective background. The projected source grid image may then be re-imaged onto the original grid element at a slight offset eliminating the need to generate a separate cutoff grid thereby reducing the amount of time required to setup and adjust the system. The digital display device is also capable of switching between a schlieren visualization capability to some other visualization capability (such as particle tracking velocimetry (PTV), particle imaging velocimetry (NV), temperature sensitive paint measurements (TSP), pressure sensitive paint measurements (PSP), photogrammetry, etc.) allowing for the simultaneous use of two different imaging techniques.

Light is projected through a grid (e.g., a Ronchi ruling) and onto a background, where it forms an image of the ruling. The light from this projected image is then reflected back onto the same grid, with a polarizing refractor (e.g., a Rochon polarizing prism) imparting a small offset between the projected and reflected light, and then on to an imaging camera. Thus, a separate source and cutoff grid is not needed, resulting in a focusing schlieren system that is compact and easy to construct and align. In some embodiments, translation of the polarizing refractor along the instrument axis provides a sensitivity adjustment of the resulting schlieren images. Manipulation of the polarization state of the light through the system allows the projected and reflected light to be coincident, maintaining a small footprint for the system, which can be mounted to the front of the imaging camera.

A rotor system comprises a rotor constructed and arranged to rotate about an axis of rotation. A source of electromagnetic radiation is positioned at a first position of the rotor, the source of electromagnetic radiation configured to emit electromagnetic radiation at one or more wavelengths. The rotor system further includes a sample region. A detector is positioned at a second position of the rotor, the detector constructed and arranged to receive electromagnetic radiation that traverses at least a portion of the sample region.

Embodiments of the present application are directed toward a focusing Schlieren technique that is capable of adding color-coded directional information to the visualization of density gradients. Other advantages of the technique can include that it does not require manual calibration, has a simple design and is sensitive enough to be used in compact experimental setups. Certain embodiments include the use of a color-coded source image that replaces the conventional source grid. The technique may benefit from a computer-controlled digital background, which is used for both illumination and display of color-coded source images.

Embodiments of the present application are directed toward a focusing Schlieren technique that is capable of adding color-coded directional information to the visualization of density gradients. Other advantages of the technique can include that it does not require manual calibration, has a simple design and is sensitive enough to be used in compact experimental setups. Certain embodiments include the use of a color-coded source image that replaces the conventional source grid. The technique may benefit from a computer-controlled digital background, which is used for both illumination and display of color-coded source images.

A cover glass inspecting apparatus may include a transfer module for transferring a cover glass. The cover glass may include a flat plate portion extending in first and second directions crossing with each other and edge portions protruding in a third direction perpendicular to the first and second directions and connected to outer circumference of the flat plate portion, wherein the flat plate portion may include first and second surfaces facing each other. The cover glass inspecting apparatus may further include a first optical module for photographing the first surface, a second optical module for photographing the second surface, and a control module for reading images of the cover glass taken by the first optical module and the second optical module. The first optical module may include a first sub optical module for photographing the first surface and a second sub optical module for photographing the edge portions.

A system for visualizing catheter irrigation, the system includes a fluid container, a pump, a schlieren imaging assembly and a processor. The fluid container is configured to: (i) contain a first fluid, which is at least partially transparent and has a first temperature, and (ii) receive into the first fluid a catheter having one or more irrigation holes. The pump is configured to inject, through the one or more irrigation holes, a second fluid, which is at least partially transparent and has a second different temperature. The schlieren imaging assembly is configured to acquire schlieren images of turbulence occurring in the first fluid when injecting the second fluid, and the processor is configured to visualize the irrigation using the schlieren images.

According to one embodiment, an optical test apparatus includes a first aperture, a second aperture, an image sensor, and a first lens. The first aperture includes a first aperture plane provided with a first wavelength selecting region. The second aperture includes a second aperture plane provided with a second wavelength selecting region different from the first wavelength selecting region. The image sensor is configured to image a light beam passing through the first aperture plane and the second aperture plane and reaching an imaging plane. The first lens is configured to make a light beam passing through the first aperture plane and the second aperture plane be incident on the imaging plane.

According to one embodiment, a measurement method includes: acquiring a first picture including a background image and a substance, the substance allowing transmission of light from the background image; acquiring a second picture including the background image and the substance in a different positional relation with respect to the first picture; and calculating a first displacement amount representing a difference in position of the background image between the first picture and the second picture.