A Macro Lens-Based Optical System Design for Phototherapeutic Instrumentation.

Light emitting diode (LED) and ultrasound have been powerful treatment stimuli for tumor cell growth due to non-radiation effects. This research is the first preliminary study of tumor cell suppression using a macro-lens-supported 460-nm LED combined with high-frequency ultrasound. The cell density, when exposed to the LED combined with ultrasound, was gradually reduced after 30 min of induction for up to three consecutive days when 48-W DC, 20-cycle, and 50 Vp-p sinusoidal pulses were applied to the LEDs through a designed macro lens and to the ultrasound transducer, respectively. Using a developed macro lens, the non-directional light beam emitted from the LED could be localized to a certain spot, likewise with ultrasound, to avoid additional undesirable thermal effects on the small sized tumor cells. In the experimental results, compared to LED-only induction (14.49 ± 2.73%) and ultrasound-only induction (13.27 ± 2.33%), LED combined with ultrasound induction exhibited the lowest cell density (6.25 ± 1.25%). Therefore, our measurement data demonstrated that a macro-lens-supported 460-nm LED combined with an ultrasound transducer could possibly suppress early stage tumor cells effectively.

Ultrawide-angle optical system design for light-emitting diode-based ophthalmology and dermatology applications.

BACKGROUND: Compared to laser, light-emitting diodes - non-coherent and divergent light sources requires that the developed optical system support steering and focusing of light on the desired target when acquiring information regarding human tissues. OBJECTIVE: A new optical system with an ultrawide angle was designed to cover large areas of the eye, including facial areas near the eye, in order to overcome the limited field of view of optical systems used for ophthalmology and dermatology applications. METHODS: To achieve a compact and handheld optical system for ophthalmology and dermatology applications, a contrast auto-focus (AF) method must be used, and the weight reduction of the AF group is considered during the design process to satisfy the effective focal length (EFL), back focal length (BFL), and front focal length (FFL) in the proposed optical system using Gaussian-bracket method. RESULTS: The designed optical system can focus from infinity to a magnification of -0.19 times, representing a distance of 114.359 mm from the first surface of the optical system to the object. The AF lens moving distance from infinity to the minimum distance is approximately 4.984 mm. The full width at half maximum (FWHM) values of the red, green, and blue light-emitting diodes were 16 mm, 35 mm, and 22 mm, respectively. CONCLUSIONS: We have designed an ultrawide-angle optical system for compact optical systems that are suitable for high-performance ophthalmology and dermatology applications.

Chromatic aberration free reflective mirror-based optical system design for multispectral photoacoustic instruments.

BACKGROUND: Current multispectral photoacoustic instruments must use large and separate combinational structures to obtain various biological tissue information for multispectral ranges. OBJECTIVE: The optical aberration generated from the multispectral photoacoustic systems may reduce the image quality of biological tissue because the improper structures for combining light of different wavelength cannot produce good optical ray convergence points. To prevent this, complex combined structures need to be considered at the design level for multispectral photoacoustic systems. METHODS: In place of an optical refracted lens system, reflective mirrors could be designed for optical systems. To verify our proposed idea, we assessed optical distortion performance using red, green, and blue light, and combined optical light sources to compare their chromatic aberration characteristics. RESULTS: The high optical performance is realized regardless of the wavelength for a light source combined with multiple wavelengths, because our optical system was designed with only a reflective surface. CONCLUSIONS: The designed optical system using a reflective mirror can provide multispectral optical sources (such as infrared, visible, and ultraviolet optical lights) with only one light ray path, without any chromatic aberrations.

Development of a Multiwavelength Visible-Range-Supported Opto⁻Ultrasound Instrument Using a Light-Emitting Diode and Ultrasound Transducer.

A new multiwavelength visible-range-supported opto⁻ultrasound instrument using a light-emitting diode and ultrasound transducer was developed in order to produce multiwavelength visible light with minimized color aberration errors, and detect ultrasound signals emitted from the target. In the instrument, the developed optical systems can provide multiwavelength optical transmission with low optical aberration within 10-cm ranges that are reasonably flat in the modulation transfer function at spatial frequencies of 20 and 40 lp/mm, except at the end of the diagonal edge of the samples. To assess the instrument capability, we performed pulse⁻echo responses with Thunnus obesus eye samples. Focused red, green, blue and white light rays from an integrated red, green and blue LED source were produced, and echo signal amplitudes of 33.53, 34.92, 38.74 and 82.54 mV, respectively, were detected from the Thunnus obesus eye samples by a 10-MHz focused ultrasound transducer. The center frequencies of the echo signal when producing red, green, blue and white LED light in the instrument were 9.02, 9.05, 9.21 and 8.81 MHz, respectively. From these tests, we verify that this instrument can combine red, green and blue LED light to cover different wavelengths in the visible-light range and detect reasonable echo amplitudes from the samples.

Development of a Double-Gauss Lens Based Setup for Optoacoustic Applications.

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.