Development of the fast astigmatic auto-focus microscope system

Hsu, Wei-Yao; Lee, Chien-Shing; Chen, Po-Jui; Chen, Nien-Tsu; Chen, Fong-Zhi; Yu, Zong-Ru; Kuo, Ching-Hsiang; Hwang, Chi‐Hung

doi:10.1088/0957-0233/20/4/045902

Cited by 72 publications

(37 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Usually, opticians try to avoid astigmatism in their optical systems. Nevertheless, it is commonly used in CD or DVD players to measure the distance between the disk and the reader head as well as for other auto-focus systems (Hsu et al 2009). Another approach that produces an astigmatic image aberration is utilizing a tilt angle between the measurement volume and the camera, which results in off-axis imaging (Hain and Kähler 2006).…”

Section: Imaging Based On Aberrations (Astigmatism)mentioning

confidence: 99%

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

Cierpka

Kähler

2011

J Vis

129

View full text Add to dashboard Cite

The reliable measurement of the 3D3C velocity field in microfluidic devices becomes more and more important for future optimization and developments for lab-on-a-chip applications or point-of-care medical diagnosis systems. In the past years, different particle-based imaging methods, such as confocal scanning microscopy, holography, stereoscopic and tomographic imaging or approaches based on defocused particle images or optical aberrations have been developed and applied successfully to measure velocity fields in microfluidic systems. The benefits and drawbacks of these methods will be discussed in detail as the proper understanding of the measurement principle is essential to select the most appropriate technique for a desired measurement application. Once an imaging method is chosen, the velocity can be estimated by correlation-based methods or tracking approaches. The advantages and disadvantages of both methods and the importance of image preprocessing will also be discussed in detail.

show abstract

Section: Imaging Based On Aberrations (Astigmatism)mentioning

confidence: 99%

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

Cierpka

Kähler

2011

J Vis

129

View full text Add to dashboard Cite

show abstract

“…As discussed in [4], existing autofocusing microscopes can be broadly classified as either image-based (i.e., software) or optics-based (i.e., hardware). Image-based or software autofocusing microscope is based on the image sharpness identification or the image spatial frequency function [5]. These kinds of microscopes are cheap, reliable and robust, therefore they have many industrial applications [6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Precise autofocusing microscope with rapid response

Liu

Jiang

2015

Optics and Lasers in Engineering

View full text Add to dashboard Cite

“…Miniature QPDs extracted from optical pick-up heads of CD/DVD players have already been used in development of an auto-focusing probe for profile measurement 24 , an auto-focusing microscope 25,26 , and an Atomic Force Microscope 27 . However, to the best of our knowledge, their use is not known in the optical tweezers/PFM community despite they being very useful for this application.…”

Section: G Applications and Future Workmentioning

confidence: 99%

Measurement of probe displacement to the thermal resolution limit in photonic force microscopy using a miniature quadrant photodetector

Pal

Haldar

Roy

et al. 2012

Review of Scientific Instruments

View full text Add to dashboard Cite

A photonic force microscope comprises of an optically trapped micro-probe and a position detection system to track the motion of the probe. Signal collection for motion detection is often carried out using the backscattered light off the probe -however, this mode has problems of low S/N due to the small backscattering cross-sections of the micro-probes typically used. The position sensors often used in these cases are quadrant photodetectors. To ensure maximum sensitivity of such detectors, it would help if the detector size matched with the detection beam radius after the condenser lens (which for backscattered detection would be the trapping objective itself). To suit this condition, we have used a miniature displacement sensor whose dimensions makes it ideal to work with 1:1 images of micron-sized trapped probes in the back-scattering detection mode. The detector is based on the quadrant photo-IC in the optical pick-up head of a compact disc player. Using this detector, we measured absolute displacements of an optically trapped 1.1 µm probe with a resolution of ∼10 nm for a bandwidth of 10 Hz at 95% significance without any sample or laser stabilization. We characterized our optical trap for different sized probes by measuring the power spectrum for each probe to 1% accuracy, and found that for 1.1 µm diameter probes, the noise in our position measurement matched the thermal resolution limit for averaging times up to 10 ms. We also achieved a linear response range of around 385 nm with crosstalk between axes 4% for 1.1 µm diameter probes. The detector has extremely high bandwidth (few MHz) and low optical power threshold -other factors that can lead to it's widespread use in photonic force microscopy.

show abstract

Development of the fast astigmatic auto-focus microscope system

Cited by 72 publications

References 9 publications

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

Precise autofocusing microscope with rapid response

Measurement of probe displacement to the thermal resolution limit in photonic force microscopy using a miniature quadrant photodetector

Contact Info

Product

Resources

About