Parallel Confocal Laser Microscope System using Integrated Parallel Optical Devices

Summary

The temporal resolution of a confocal laser microscope, by which 3-dimensinal data of samples are obtained, usually suffers from the slow speed of the image acquisition devices, such as CCDs or scanning mirrors. Here we propose a confocal microscope system where parallel optoelectronic devices are employed aiming at obtaining high frame-rate of 3-dimensional data that provides dynamical properties of samples or real-time feedback for manipulation (see Figure 1). A Smart Pixel yields pixel-parallel data processing capability owing to its integrated optical devices and electronic processing circuitry on a same chip. Based on the data obtained by smart pixels, optical system configuration, illumination, or the status of specimen is adaptively configured. Comparing to the parallel-pinhole-based confocal laser microscope system, the optical loss to make the light source array is ideally avoided since the VCSEL itself is the point-source array. In addition, each pixel illumination could be independently controlled and therefore the dynamic range and sensitivity of each pixel is improved.

We have performed basic experiments on a system composed of an 8x8 vertical cavity surface emitting laser (VCSEL) array, Si PD array to which 64-channel parallel amplifier and thresholding circuits are attached, and processing element (PE) array with a pitch of 250um, as shown in Figure 2. Each PE contains an arithmetic logic unit (ALU), 24-bit local memory, and electrical connections to neighboring pixels, that provides fast processing versatility such as edge extraction, moving object recognition. Vibrating a sample by a piezo micro stage, we have successfully obtained a dynamical property, which is a one-dimensional moment of the moving sample, on the basis of the data obtained by the experimental system over the range of conventional video frame-rate.

Figure 1: Parallel Confocal Microscope System Using Integrated Optical Devices


Figure 2: Experimental System

Reference

1. Makoto Naruse and Masatoshi Ishikawa: A parallel confocal microscope using smart pixel, Japanese Society of Applied Physics Conference (Tokyo, March 29, 2000) [pdf file(49k) in Japanese]
2. M. Naruse and M. Ishikawa: Parallel Confocal Laser Microscope System using Smart Pixel Arrays, The International Symposium on Optical Science and Technology, conference 4092: Novel Optical Systems Design and Optimization III (San Diego, August 1st, 2000)/ Proceedings of SPIE, Vol. 4092, pp. 94-101. [pdf file(128k)]
3. M. Fujita, M. Naruse, and M. Ishikawa : Parallel confocal microscope using vertical-cavity surface-emitting laser array, Microscopy and Microanalysis 2001 (Long Beach, California, 2001.8.7) pp.1004-1005, 2001