Three types of reflectors, including the distributed Bragg reflectors (DBRs), the first hybrid reflectors composed of DBR and Al mirror (DBR-Al), and the second hybrid reflectors composed of DBR, an additional low-refractive-index layer, and Al mirror (DBR-L-Al), were investigated by use of thin-film theory at the central wavelength of 300 nm for flip-chip ultra-violet light-emitting diodes (UV-LEDs). The number of DBR pairs and various high-refractive-index materials were studied. It is shown that the lossless materials with high refractive-index contrast should be selected for DBRs, and the DBR-Al hybrid reflectors provides higher reflectance comparing to DBRs. However, the Al mirror causes a sharp drop near the central wavelength and a blue shift of the peak position. These drawbacks can be suppressed by additional low-refractive-index layer attached on the Al mirror. In addition, the DBR-L-Al reflector leads to higher reflectivity and larger FWHM as compared to DBR-Al reflectors. By use of Monte Carlo ray tracing method, the light-extraction efficiency (LEE) for flip-chip UV-LEDs with (SiO2/ZrO2) 3 -SiO2-Al hybrid reflector or perfect mirror were simulated. The calculated LEE for the (SiO2/ZrO2) 3 -SiO2-Al hybrid reflector is 97 % of that for the perfect mirror. Moreover, the sharp drop in the angular reflectance spectrum of the (SiO<sup>2</sup>/ZrO<sup>2</sup>)<sup>3</sup> -SiO<sup>2</sup>-Al hybrid reflector induces a slightly reduction of light intensity as compared to the perfect mirror.
In view of limitation for LED optical design method as ideal point source, a new uniform illumination optical design
method of freeform lens for a high-power LED is present in the paper.By establishing an energy corresponding
relationship between the extended LED source and the point illumination of the receiving surface, a freeform lens optical
model achieving uniform illumination in target plane is obtained.The optical simulation results of uniform light intensity
curve of the model are compared with the one designed by an approximate point source method. The results show that
the new method can effectively overcome the shortages from the point source design.It is more accurately to control the
correspondence relationship of light energy and the outgoing direction of light.The illumination uniformity of the
freeform lens is greater than 75% and also meets the design requirements.
In this paper, the transmission principle of light crossing the light guide panel was analyzed and a calculating method of
the net dot distribution was deduced according to the illumination distribution of LED. Using this method, the light guide
panel net dot distribution of a small size backlight was calculated. And, in the light of net not distribution regulation, the
net dot layout was optimized and simplified associating with area segmentation adjustment method. Optical model was
made and ray tracing was done by optical design software, the simulation result indicate that the surface luminance
uniformity of the backlight is 87% and the light efficiency is 71%, which is achieved by less LED sources and area
segmentations compared with the same size backlight. The net dot of light guide panel sample was made by laser
engraving. The luminance uniformity of testing is consistent with that of simulation.
Based on the non-imaging particularities of LED optical sources , considering the impact of several factors respectively
such as the distribution of chips, the size of the reflector and the refractive index of packaging material , the packaging of
multi-chip LED array source is designed and simulated by using geometrical modeling for optical components and
Monte Carlo non-sequence ray tracing method. In this paper put emphasis on the optical design of the packaging
structure to the 2 × 2 LED array source, and get the different luminous efficiency and light intensity distributions by
changing the packaging parameters of the model. The results showed that the distributions of light intensity under the
different parameters have certain regularity. These laws have the practical guidance to the multi-chip LED lighting
system design and production, and these are also helpful to reduce the experiment costs in LED packaging manufactures.
Conventional LED optical design method that is commom for the point source approximation based on energy
conservation and the law of refraction and reflection, and the final optical model solved by stepping method. The method
that plays an important role in the LED second optical design is not applicable to the LED extended sources. In this
paper, the optical design method is present for LED extended sources by using edge ray theorem, and light intensity
optical model has be established by this method. The optical simulation results of uniform light intensity curve of the
model are compared with the models designed by approximate design method of point source. The results show that the
directions of outgoing light lines can be controlled more accurately by edge ray theorem and have better uniformity. The
method can be applied for the LED encapsulation optical system design and multi-chip source optical design of high-power LED. It can improve the design accuracy and save design cost.
Based on optic fiber beam sensor, a miniaturized laser induced fluorescence optical fiber detection system using solid-state laser (473nm) as excitation source is developed. The advantage of the
LIF-D system are simple structure, small size, low cost, high sensitivity and high anti-disturbing. And the photon count method is used to improve the sensitivity of the detection. Using Sodium fluorescein as the test sample, distinct fluorescence signal with good repeatability is showed in the experiment. The concentration detection limit is up to 3×10<sup>-13</sup>mol/L. the linear dynamic range is from 10<sup>-6</sup> to 10<sup>-13</sup> mol/L. It also shown that there was a nicer linear relation between the peak value of fluorescence signal to Sodium fluorescein concentration. Its relation coefficient is 0.99954. By changing detection cells this integrated detection system can be applied in micro flow analysis and for the normal biotechnology analysis of DNA.