A virtual size-variable pinhole for single photon confocal microscopy

Guangjun Gao; Bahram Khoobehi

doi:10.1117/12.2000240

13 March 2013 A virtual size-variable pinhole for single photon confocal microscopy

Guangjun Gao, Bahram Khoobehi

Proceedings Volume 8573, Design and Quality for Biomedical Technologies VI; 85730A (2013) https://doi.org/10.1117/12.2000240
Event: SPIE BiOS, 2013, San Francisco, California, United States

Abstract

Pinhole is a critical device in single photon confocal microscopy (SPCM) owning to its ability to block the background noise scattered from back and forth of the focal plane. Without pinhole, the sectioning ability of SPCM will be degraded and many background noise signals will occurred together with useful signals, and sometimes these bad noises can submerge the details that we are interested in. However a pinhole with too small diameter will block both background noises and part of signals and decrease the intensity of the image. Therefore in many cases pinhole size should be selected carefully. Unfortunately because of constrains in mechanics, a pinhole that can change its size continuously, for example from 10 μm to 100 μm, is unavailable. For most commercial confocal microscopies, only several discrete pinhole sizes are provided, such as 10 μm, 30 μm, 60 μm etc. Things will be even harder for some imaging systems which use the input interface of a single mode fiber as the pinhole of SPCM, and then the pinhole size of these systems will be fixed, which far limit the optimization of systems’ performance. In this paper, we design a size-variable pinhole setup that can offer a virtual pinhole with its diameter adjustable, which includes a physical pinhole (or single mode fiber) and a fine designed zoom relay (ZR) optical system. The magnification ratio of this ZR can vary smoothly while keeping the conjugation distance unchanged. The aberrations of the ZR are well balanced and diffraction-limited image performance are obtained so that the virtual pinhole can block background scattering noise and pass the in-focus signal effectively and accurately. Simulation results are also provided and discussed.

Citation Download Citation

Guangjun Gao and Bahram Khoobehi "A virtual size-variable pinhole for single photon confocal microscopy", Proc. SPIE 8573, Design and Quality for Biomedical Technologies VI, 85730A (13 March 2013); https://doi.org/10.1117/12.2000240

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