Optical design and fabrication of palm/fingerprint uniform illumination system with a high-power near-infrared light-emitting diode

Abstract

In order to meet the requirements of uniform illumination for optical palm/fingerprint instruments and overcome the shortcomings of the poor uniform illumination on the working plane of the optical palm/fingerprint prism, a novel secondary optical lens with a free-form surface, compact structure, and high uniformity is presented in this paper. The design of the secondary optical lens is based on emission properties of the near-infrared light-emitting diode (LED) and basic principles of non-imaging optics, especially considering the impact of the thickness of the prism in the design. Through the numerical solution of Snell's law in geometric optics, we obtain the profile of the free-form surface of the lens. Using the optical software TracePro, we trace and simulate the illumination system. The results show that the uniformity is 89.8% on the working plane of the prism, and the test results show that the actual uniformity reaches 85.7% in the experiment, which provides an effective way for realizing a highly uniform illumination system with high-power near-infrared LED.

Optimized Design of a Pump Laser System for a Spin Exchange Relaxation Free Inertial Measurement Device

“…The power stability can be defined as follows: where, P max and P min are, respectively, the maximum and minimum value of output power during testing, and is the average value. The uniformity of the spot can be calculated as follows [ 31 ]: where M is the number of sampling points, E (W/m 2 ) = P (W) /A (m 2 ) , P is the laser power, A is the target area, E i is the corresponding value at each point, and is the averaged value.…”

“…Most importantly, the incident angle of the laser passing through the vapor cell is not considered, which causes the refraction or reflection of light, and thereby results in a light shift or non-uniform intensity distribution. Compared with the other beam shaping methods [ 26 , 27 , 28 , 29 , 30 ], the method with a freeform surface lens [ 31 , 32 ] with a high degree of freedom and less energy loss is better for achieving the uniform distribution of intensity of non-ideal laser sources. At shorter distances, a better uniform intensity distribution can be achieved by using only one freeform surface lens [ 33 ], especially for a big spherical vapor cell.…”

Biometric authentication security enhancement under quantum dot light-emitting diode display via fingerprint imaging and temperature sensing

“…Recently, financial transactions and online shopping using mobile devices have increased dramatically. 1 – 3 The importance of biometric authentication in mobile devices has been increasing owing to its excellent security and convenience. 4 – 6 Mass-produced smartphones such as Samsung Galaxy, released in 2020, use optical fingerprint recognition on screen.…”

“…Thus, this study successfully enhanced biometric authentication security, through fingerprint recognition based on image sensing using an optical system with micrometer-sized apertures and skin-temperature detection under QLED displays.Recently, financial transactions and online shopping using mobile devices have increased dramatically. [1][2][3] The…”

“…Recently, financial transactions and online shopping using mobile devices have increased dramatically. [1][2][3] The…”