Peter Egelberg

High-resolution digital transmission microscopy—a Fourier holography approach

A spherical reference field is used to construct a digital holography system with a demonstrated resolution down to 228 line pairs per mm. The reference field origin from a GRIN lens placed 1mm from the illuminated object. This allows the use of a standard sensor to record the hologram with the required numerical aperture. The image is determined by evaluation of the Rayleigh-Sommerfeld diffraction integral that relates the object field in the image plane to the object field in the sensor plane. Experimental results are given for two charge couple device sensors and one complementary metaloxide- semiconductor active pixel sensor.

A Custom Image Convolution DSP with a Sustained Calculation Capacity of >1 GMAC/s and Low I/O Bandwidth

A customized processor for real time image convolution has been designed to increase the performance of an instrument for automated cereal grain quality assessment. Image convolution requires an extensive amount of calculation capacity and a corresponding amount of data transfers, hard to achieve with standard processors in real time. Therefore, a tailored architecture with a streamlined dataflow has been developed with emphasis on a system design perspective. The designed processor has a sustained calculation capacity of >1 GMAC/s and on-chip line buffers reduce the amount of external data transfers. Hence, the complexity of the designed processor has been increased to gain a lower complexity of the complete system. To achieve powerful and versatile filtering the size of the programmable kernel functions have been maximized to 15 × 15.

Label-free high temporal resolution assessment of cell proliferation using digital holographic microscopy

Cell proliferation assays are widely applied in biological sciences to understand the effect of drugs over time. However, current methods often assess cell population growth indirectly, that is, the cells are not actually counted. Instead other parameters, for example, the amount of protein, are determined. These methods often also demand phototoxic labels, have low temporal resolution, or employ end‐point assays, and frequently are labor intensive. We have developed a robust and label‐free kinetic cell proliferation assay with high temporal resolution for adherent cells using digital holographic microscopy (DHM), one of many quantitative phase microscopy techniques. As no labels or stains are required, and only very low intensity illumination is necessary, the technique allows for noninvasive continuous cell counting. Only two image processing settings were adjusted between cell lines, making the assay practical, user friendly, and free of user bias. The developed direct assay was validated by analyzing cell cultures treated with various concentrations of the anti‐cancer drug etoposide, a well‐established topoisomerase inhibitor that causes DNA damage and leads to programmed cell death. After treatment, the unstained adherent cells were nondestructively imaged every 30 min for 36 h inside a cell incubator. In the recorded time‐lapse image sequences, individual cells were automatically identified to provide detailed growth curves and growth rate data of cell number, confluence, and average cell volume. Our results demonstrate how these parameters facilitate a deeper understanding of cell processes than what is achievable with current single‐parameter and end‐point methods.

Accelerating signal processing algorithms in digital holography using an FPGA platform

This paper describes the implementation of a custom DSP system to accelerate image processing algorithms used in the field of digital holography. The system, implemented on an FPGA platform, is intended for real-time reconstruction of images captured on a large image sensor. Due to the large amount of processing information, it is not possible to perform a HDL simulation of a complete image reconstruction in reasonable time. Instead, a reconfigurable solution is being used for full scale image reconstruction, exhaustive testing of the functionality and for connecting the accelerator to external components, i.e. the image sensor, monitor output device and high-speed memory banks.

HoloMonitor M4: holographic imaging cytometer for real-time kinetic label-free live-cell analysis of adherent cells

Live-cell imaging enables studying dynamic cellular processes that cannot be visualized in fixed-cell assays. An increasing number of scientists in academia and the pharmaceutical industry are choosing live-cell analysis over or in addition to traditional fixed-cell assays. We have developed a time-lapse label-free imaging cytometer HoloMonitorM4. HoloMonitor M4 assists researchers to overcome inherent disadvantages of fluorescent analysis, specifically effects of chemical labels or genetic modifications which can alter cellular behavior. Additionally, label-free analysis is simple and eliminates the costs associated with staining procedures. The underlying technology principle is based on digital off-axis holography. While multiple alternatives exist for this type of analysis, we prioritized our developments to achieve the following: a) All-inclusive system – hardware and sophisticated cytometric analysis software; b) Ease of use enabling utilization of instrumentation by expert- and entrylevel researchers alike; c) Validated quantitative assay end-points tracked over time such as optical path length shift, optical volume and multiple derived imaging parameters; d) Reliable digital autofocus; e) Robust long-term operation in the incubator environment; f) High throughput and walk-away capability; and finally g) Data management suitable for single- and multi-user networks. We provide examples of HoloMonitor applications of label-free cell viability measurements and monitoring of cell cycle phase distribution.

A parallel 2 Gops/s image convolution processor with low I/O bandwidth

A customized image processor for real time convolution of an image has been developed. Image convolution requires an extensive amount of calculation capacity and I/O communication which is hard to sustain with standard processors in real time. Therefore, a customized processor has been designed with a tailored architecture. The processors have a total sustained calculation capacity of >2G arithmetic operations/s at 20 MHz clock frequency, surpassing that of TMS320C80 for this application due to the tailored architecture.