Disk Pickup Head Research Articles

Cell depth imaging by point laser scanning fluorescence microscopy with an optical disk pickup head

A compact, cost-effective, and position-addressable digital laser scanning microscopy (DLSM) instrument is made using a commercially available Blu-ray disc read-only memory (BD-ROM) pickup head. Fluorescent cell images captured by DLSM have resolutions of 0.38 µm. Because of the position-addressable function, multispectral fluorescence cell images are captured using the same sample slide with different excitation laser sources. Specially designed objective lenses with the same working distance as the image-capturing beam are used for the different excitation laser sources. By accurately controlling the tilting angles of the sample slide or by moving the collimator lens of the image-capturing beam, the fluorescence cell images along different depth positions of the sample are obtained. Thus, z-section images with micrometer-depth resolutions are achievable.

Position-addressable digital laser scanning point fluorescence microscopy with a Blu-ray disk pickup head

A compact and position-addressable blue ray scanning microscope (BSM) based on a commercially available Blu-ray disk pickup head (PUH) is developed for cell imaging with high resolution and low cost. The BSM comprises two objective lenses with numerical apertures (NAs) of 0.85 and 0.6 for focusing blue and red laser beams, respectively, on the sample slide. The blue and red laser beams are co-located adjacent to each other and move synchronously. A specially designed sample slide is used with a sample area and an address-patterned area for sample holding and address recognition, respectively. The blue laser beam is focused on the sample area and is used for fluorescent excitation and image capturing, whereas the red laser beam is focused on the address-patterned area and is used for address recognition and dynamic focusing. The address-patterned area is divided into 310 sectors. The cell image of each sector of the sampling area has a corresponding address pattern. Fluorescence images of monkey-derived kidney epithelial cells and fibroblast cells in which the F-actin is stained with fluorophore phalloidin CF 405 are measured by the BSM, with results comparable to those measured by a Leica TCS CP2 confocal microscope. The cell image of an area of interest can be easily tracked based on the coded address, and a large-area sample image can be accurately reconstructed from the sector images.

Laser expander design of highly efficient Blu-ray disc pickup head

We present a collimator design with a horizontal beam expander for a Blu-ray Disc pickup head. The design transforms the shape of a laser diode beam from an elliptical into circular which achieves higher efficiency in the pickup head system. In this research, we suggest two ways to do the beam expander. One way is to use two cylindrical lenses, and the other is to use two prisms.

Blu-ray Disc Pickup Head for Dual Layer

For dual-layer Blu-ray disc (BD) recording systems, the compensation of thickness differences is required. In addition the influence from the other layer should be considered. As a spherical compensation method, we have adopted a liquid crystal panel to fabricate a compact pickup head. Furthermore we have inserted a polarization diffractive optical element to reduce the influence from the other layer. In this paper, we report the readout test results of a dual-layer disc using a compact optical head.

Holographic Optical Element with High Assembly Tolerance for the Optical Module of Digital Versatile Disc Pickup-Heads

The astigmatic focus detection method and differential phase detection (DPD) tracking method are now widely used in a digital versatile disk (DVD) pickup head. The DPD tracking method requires the returning spot to remain centered in a quad detector and therefore makes the optical alignment very critical. In this paper, a novel holographic optical element (HOE) pattern design to relax the alignment tolerance and achieve a stable DPD tracking servo property is described. Simulations show that the servo signals are insensitive to photo-detector (PD) misalignment when compared to that of a conventional HOE design.

Realization of novel monolithic free-space optical disk pickup heads by surface micromachining

A novel monolithic free-space optical disk pickup head has been fabricated by micromachined micro-optical bench technology. The pickup head contains a self-aligned semiconductor edge-emitting laser, a collimating lens, a beam splitter, two focusing lenses, and two 45 degrees mirrors. All optical components are built monolithically on Si substrates. The 45 degrees mirror directs the optical output beam in the surface-normal direction. This novel design could signif icantly reduce the size and the weight of the optical pickup head as well as the cost of the assembly processes. The weight reduction could also greatly increase the data access rate.