Abstract: A real-time reference free background oriented schlieren system is provided. One embodiment includes a display device capable of generating an image pattern projected onto a retroreflective background. A beam splitter is used to transmit a portion of the projected image pattern towards a reference image sensor and another portion of the image pattern towards the retroreflective background and past a density object. The retroreflective background reflects the projected pattern back through the beam splitter and onto a signal imaging sensor. Collected data from the reference image sensor and the signal image sensor may be processed in real-time. The image pattern may be altered as necessary without requiring a new reference image, reducing the amount of time required to set up and adjust the system. A display device may be capable of switching between a schlieren visualization capability to a shadowgraph system allowing for the use of two different imaging techniques.

Abstract: An adjustable beam directing optical system for a focused laser differential interferometer (FLDI) instrument according to various aspects of the present technology may include optical half waveplate to achieve an incident linear polarization orientation with equal components of laser intensity aligned to the vertical and horizontal axis of the optical system, and an optical prism for splitting these components of an incident laser beam into two orthogonally-polarized beams equally about an optical axis of the FLDI instrument. A series of beam realignment devices positioned downstream of the optical prism are configured to selectively direct each beam to a predetermined location.

Abstract: A real-time reference free background oriented schlieren system is provided. One embodiment includes a display device capable of generating an image pattern projected onto a retroreflective background. A beam splitter is used to transmit a portion of the projected image pattern towards a reference image sensor and another portion of the image pattern towards the retroreflective background and past a density object. The retroreflective background reflects the projected pattern back through the beam splitter and onto a signal imaging sensor. Collected data from the reference image sensor and the signal image sensor may be processed in real-time. The image pattern may be altered as necessary without requiring a new reference image, reducing the amount of time required to set up and adjust the system. A display device may be capable of switching between a schlieren visualization capability to a shadowgraph system allowing for the use of two different imaging techniques.

Abstract: An adjustable beam directing optical system for a focused laser differential interferometer (FLDI) instrument according to various aspects of the present technology may include an optical half waveplate to achieve an incident linear polarization orientation with equal components of laser intensity aligned to the vertical and horizontal axis of the optical system, and an optical prism for splitting these components of an incident laser beam into two orthogonally-polarized beams equally about an optical axis of the FLDI instrument. A series of beam realignment devices positioned downstream of the optical prism are configured to selectively direct each beam to a predetermined location.

Abstract: 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.

Abstract: A real-time reference free background oriented schlieren system is provided. One embodiment includes a display device capable of generating an image pattern projected onto a retroreflective background. A beam splitter is used to transmit a portion of the projected image pattern towards a reference image sensor and another portion of the image pattern towards the retroreflective background and past a density object. The retroreflective background reflects the projected pattern back through the beam splitter and onto a signal imaging sensor. Collected data from the reference image sensor and the signal image sensor may be processed in real-time. The image pattern may be altered as necessary without requiring a new reference image, reducing the amount of time required to set up and adjust the system. A display device may be capable of switching between a schlieren visualization capability to a shadowgraph system allowing for the use of two different imaging techniques.

Abstract: One aspect of the present disclosure is an imaging system including an optical sensor defining an optical axis. The system further includes a light source. The system may include an optical beam splitter, and may also include an optional diffusing lens that may be configured to diffuse and/or collimate light from the light source and direct light exiting the diffusing lens to the optical beam splitter. The optical beam splitter is configured to direct light from the light source along the optical axis of the optical sensor.

Abstract: 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.

Abstract: One aspect of the present disclosure is an imaging system including an optical sensor defining an optical axis. The system further includes a light source. The system may include an optical beam splitter, and may also include an optional diffusing lens that may be configured to diffuse and/or collimate light from the light source and direct light exiting the diffusing lens to the optical beam splitter. The optical beam splitter is configured to direct light from the light source along the optical axis of the optical sensor.

Abstract: 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.

Abstract: An adjustable beam directing optical system for a focused laser differential interferometer (FLDI) instrument according to various aspects of the present technology may include an optical half waveplate to achieve an incident linear polarization orientation with equal components of laser intensity aligned to the vertical and horizontal axis of the optical system, and an optical prism for splitting these components of an incident laser beam into two orthogonally-polarized beams equally about an optical axis of the FLDI instrument. A series of beam realignment devices positioned downstream of the optical prism are configured to selectively direct each beam to a predetermined location.

Abstract: One aspect of the present disclosure is an imaging system including an optical sensor defining an optical axis. The system further includes a light source. The system may include an optical beam splitter, and may also include an optional diffusing lens that may be configured to diffuse and/or collimate light from the light source and direct light exiting the diffusing lens to the optical beam splitter. The optical beam splitter is configured to direct light from the light source along the optical axis of the optical sensor.