French tech for lensless acousto-optic holographic imaging
WiMi Hologram Cloud has developed an ultrafast transient optical system that integrates several key approaches for lensless holographic imaging.
The design brings together sequentially timed all-optical mapping photography (STAMP) with acousto-optic programmable dispersive filtering (AOPDF) and digital in-line holography (DIH). A paper on this was published last year in Nature from researchers at the CORIA labs of CNRS in France.
WiMi, which is listed in the US and based in China, focuses on professional areas including holographic AR automotive HUD software, 3D holographic pulse LiDAR, head-mounted light field holographic equipment, holographic semiconductor, holographic cloud software, holographic car navigation and others.
It says the ultrafast transient holographic optical imaging system will shine in developing physics, biology, medicine, chemistry, bionics, new materials, and quantum detection technologies.
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WiMi’s system simplifies the imaging process with AOPDF, which allows complete control of acquisition parameters through electrically driven phase and amplitude spectral time clipping of the imaging pulse.
Rather than using ultrafast single-shot technologies, the system enables frame rate, exposure time, and intensity to be independently adjusted over a wide range. WiMi’s design is flexible and easy to use without using complex tuning effects.
The design also employs the application of DIH without any reference beam, allowing lens-free operation for higher technical simplicity, and is also used to reconstruct objects over a wide depth of field. And the imaging speed of the system and its flexibility are verified by visualizing ultrashort events on picosecond and nanosecond time scales.
The system works on a STAMP scheme that adjusts the pulse shape in the spectral and temporal domains through the interaction of an AOPDF with an electrically driven acoustic wave and enables fully independent control of exposure time and frame rate in a tilted spectral filter. This system includes a diffractive optical element, a tilted SF, and a standard camera.
WiMi’s system provides ultra-high frame rates and a more flexible and convenient solution for ultrafast speed imaging systems. The system combines spectrally filtered STAMP with acousto-optic-based electronically controlled phase, amplitude, and DIH.
The AOPDF performs the spectro-temporal phase and amplitude calibration phase effortlessly, bypassing the complex and bulky systems usually used. This provides a fully customized pulse phase and amplitude in a simple way through the interaction of the optical pulse with the acoustic wave, making synchronous and linear FM control of femtosecond pulses possible.
The use of DIH also allows for simpler systems through its lensless operation with reconstruction and positioning of objects over a wide depth of field. Unlike conventional imaging techniques that provide images only in a single plane, DIH does not require reference to complex reconstruction algorithms and allows for real-time operation.
Using DIH also enables fast tracking of objects along a single line of sight. Then in SF-STAMP ultrafast imaging, the AOPDF pulse calibration function and DIH simplicity are utilized, and independent control of frame rate, exposure time, and frame intensity, as well as ultrafast imaging of ultrashort light, is achieved.
The CNRS paper on “Acousto-optically driven lensless single-shot ultrafast optical imaging” is here: www.nature.com/articles/s41377-022-00759-y
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