Abstract
In optoacoustic (photoacoustic) systems, different echo signal intensities such as amplitudes, center frequencies, and bandwidths need to be compensated by utilizing variable gain or time-gain compensation amplifiers. However, such electronic components can increase system complexities and signal noise levels. In this paper, we introduce a double-Gauss lens to generate a large field of view with uniform light intensity due to the low chromatic aberrations of the lens, thus obtaining uniform echo signal intensities across the field of view of the optoacoustic system. In order to validate the uniformity of the echo signal intensities in the system, an in-house transducer was placed at various positions above a tissue sample and echo signals were measured and compared with each other. The custom designed double-Gauss lens demonstrated negligible light intensity variation (±1.5%) across the illumination field of view (~2 cm diameter). When the transducer was used to measure echo signal from an eye of a bigeye tuna within a range of ±1 cm, the peak-to-peak amplitude, center frequency, and their −6 dB bandwidth variations were less than 2 mV, 1 MHz, and 6%, respectively. The custom designed double-Gauss lens can provide uniform light beam across a wide area while generating insignificant echo signal variations, and thus can lower the burden of the receiving electronics or signal processing in the optoacoustic system.
Highlights
Ultrasound is widely used in a variety of the applications such as skin, intravascular, and small animal imaging; nondestructive testing; and sound navigation and ranging, because ultrasound machines can provide safe, real-time information through non-ionizing radiation-based methods [1,2,3,4].In contrast to X-ray and optical imaging modalities, ultrasound is able to achieve higher spatial resolution of a target deep within tissue but it often suffers from low contrast due to similar acoustic properties of soft tissues [5,6,7]
We used light modulation for the optoacoustic applications such that after the light was located in the image plane of the designed double-Gauss lens, we investigated the distribution was located in the image plane of the designed double-Gauss lens, we investigated the distribution of of the light intensity in the opposite plane
We proposed an optoacoustic system using a double-Gauss lens with the goal of providing a large field of view with uniform light intensity
Summary
Ultrasound is widely used in a variety of the applications such as skin, intravascular, and small animal imaging; nondestructive testing; and sound navigation and ranging, because ultrasound machines can provide safe, real-time information through non-ionizing radiation-based methods [1,2,3,4].In contrast to X-ray and optical imaging modalities, ultrasound is able to achieve higher spatial resolution of a target deep within tissue but it often suffers from low contrast due to similar acoustic properties of soft tissues [5,6,7]. Optoacoustic systems have been introduced because the low contrast of traditional ultrasound methods are unable to provide high enough resolution for soft tissues such as blood vessel and hemoglobin [10,11]. The optoacoustic systems can achieve a high optical contrast at ultrasound penetration depth and spatial resolution which are essential characteristics to differentiate soft tissue properties [12,13]. This is possible because, in the optoacoustic systems, the light is utilized as the transmitting source and a transducer as the receiving source to detect the acoustic signal [10]
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