Search results

The purpose of this paper is to improve the quality of additive manufactured optically translucent parts by investigating the manufacturing issues, analyzing lithophane production criteria and identifying the best translucent material and additive manufacturing (AM) technology.

Figured lithophanes were laser sintered on a 3D Systems SinterStation® HiQ™ with varying layer thickness and plate thickness. Laser sintered (LS) polyamide (PA) 12 blanks were cyanoacrylate infiltrated and polished. Optical properties and performance were compared with the original LS blanks. Lithophanes and blanks were manufactured using 3D systems stereo lithography apparatus (SLA)® Viper ™si2 station, and optical properties and lithophane performance were compared with the LS specimens.

When building in the XY plane, it is optimal to sinter with the minimum layer thickness (0.076 mm) and maximum plate thickness (5 mm). Cyanoacrylate infiltration and polishing assists in reducing the LS PA 12 plate surface roughness, but polishing does not affect the lithophane performance. The best LS candidate should have an absorption coefficient of 0.5/mm using a white light source. Improved resolution but reduced contrast was observed on stereolithography (SL) specimens compared to LS parts.

Transmittance experiments were performed on three SL parts which was not sufficient for optical property calculation. Limited literature was found for new material exploration.

It is the first effort to study systematically quality improvement issues of LS PA optically translucent parts. A comparison is made of optical performance between parts made using LS and SL.

Summarises the presentations made at the UK Industrial Vision Association’s annual general meeting in September 1999, Nottiungham, UK, entitled “Innovations in illumination for machine vision”.

The purpose of this paper is to review the novel application of surface plasmon resonance (SPR) in sensing heavy metal ions and the development of SPR to become an alternative heavy metal ions sensor.

The possible dangerous toxic effects of heavy metal ions are revealed in the short introduction. The existing conventional methods for sensing heavy metal ions and their drawbacks are also discussed. To overcome these drawbacks, SPR has been investigated from the basic principle to the potential alternative in sensing heavy metal ions.

Application of SPR in sensing heavy metal ions emerged a decade ago. A wide range of active layers or recognition elements (e.g. polymer, protein, nanoparticles) have been developed to combine with SPR. The detection limit, sensitivity and selectivity of SPR sensing in heavy metal ions have been improved from time to time, until the present.

This paper provides up-to-date and systematic information on SPR sensing for heavy metal ions. Different advancements on active layers or recognition molecules have been discussed in detail and arranged in the order of their chronological evolution. The present review may provide researchers with valuable information regarding novel heavy metal ions sensor using SPR and encourage them to take this area for further research and development.

This paper seeks to describe automated lamp manufacturing.

The paper provides information on the automated manufacture of incandescent, fluorescent and light‐emitting diodes (LEDs).

The paper finds that the automated manufacture of conventional lamp types is similar, but LEDs require totally different techniques developed from the semiconductor industry.

The paper should be of value in terms of understanding the basics of automated lamp manufacturing, especially with LEDs, as these will be highly important general lighting products to save energy and provide innovation in lighting design in the near future.

Rapid prototypes formed using stereolithography (SL) method have to undergo post‐curing to increase their strength and rigidity. This study attempts to reduce, if not eliminate, post‐cure distortion by characterising curing behaviours. Curing (both heat and UV initiated) characteristics of an acrylic‐based photopolymer under actual fabrication conditions were studied using Raman spectroscopy as well as differential scanning calorimetry (DSC) and differential scanning photo‐calorimetry (DSP). Specimens of single photopolymer lines were created using a SL machine. Raman spectroscopy was used to quantify the curing percentage at different areas on the cross‐section of these lines. Curing percentages before and after post‐curing were also obtained from the experiments. Difference in percentage of post‐curing gave an indication of the distortions faced. It was found that uncured and partially cured resins trapped within the photopolymer resulted in inhomogeneity of curing in the specimens causing shrinkage and distortion.

The purpose of this paper is to report selected optical properties of laser sintered polyamide 12 blank plates under different monochromatic and white light conditions and to apply these properties in production of laser sintered lithophanes.

A UNICO 1201E spectrophotometer was used to measure the transmittance of laser sintered polyamide 12 plates as a function of plate thickness. Monochromatic light-emitting diodes were used to assess the wavelength dependence on the transmission and contrast as captured by a SONY DSC-W55 camera.

The transmittance decreased with increasing plate thickness which varied significantly depending on the monochromatic wavelength. Highest transmission was observed using green light (525 nm) and poorest transmission was measured for yellow light (589 nm).

There is a limit to the amount of contrast obtained in polyamide lithophanes because the thickness of the plates is limited to less than about 5 mm. Greater thickness results in discernible topology on the lithophane which impairs the quality of the image.

Light transmittance of polyamide 12 plates under different lighting conditions is reported and applied to optically defined laser sintered lithophanes.

To evaluate the photoelectrochemical characteristics of polymer doped with CdSe and CdSe/TiO₂ for improved photoelectric conversion efficiency.

A method was set‐up to dope the nano‐CdSe with poly‐perylene‐tetracarboxylic imide (PPI) in the nano‐TiO₂/ITO films, which were characterised by X‐ray diffraction; electrochemical analytical system; multifunctional grating spectrometer; digital photometer and ultrasonic cleanout instrument, etc.

The modification of PPI doped with CdSe and CdSe/TiO₂ showed significant elevation of the monochromatic incident photo‐to‐electron conversion efficiency (IPCE) of the photoelectrode, which was about 3 per cent. The doping caused a tone up separate efficiency of charge, restraining the complex of electron‐cavity by doped nano‐CdSe. Therefore, the photocurrent of the TiO₂ film doped with nano‐CdSe was about three times higher than that without.

The mixed film could also be formed from conjugated polymer mixed with polymer and inorganic particle, based on polymer doped with CdSe and CdSe/TiO₂. In addition, the monochromatic incident IPCE of the photoelectrode needs to be extensively studied.

The treatment method developed provided a practical and effective solution to increasing the ICPE.

The method for doping polymer with CdSe and CdSe/TiO₂ was novel and could probably be adapted for the manufacture of solar cell.

Fixed mode noise and random mode noise always exist in the image sensor, which affects the imaging quality of the image sensor. The charge diffusion and color mixing between pixels in the photoelectric conversion process belong to fixed mode noise. This study aims to improve the image sensor imaging quality by processing the fixed mode noise.

Through an iterative training of an ergoable long- and short-term memory recurrent neural network model, the authors obtain a neural network model able to compensate for image noise crosstalk. To overcome the lack of differences in the same color pixels on each template of the image sensor under flat-field light, the data before and after compensation were used as a new data set to further train the neural network iteratively.

The comparison of the images compensated by the two sets of neural network models shows that the gray value distribution is more concentrated and uniform. The middle and high frequency components in the spatial spectrum are all increased, indicating that the compensated image edges change faster and are more detailed (Hinton and Salakhutdinov, 2006; LeCun et al., 1998; Mohanty et al., 2016; Zang et al., 2023).

In this paper, the authors use the iterative learning color image pixel crosstalk compensation method to effectively alleviate the incomplete color mixing problem caused by the insufficient filter rate and the electric crosstalk problem caused by the lateral diffusion of the optical charge caused by the adjacent pixel potential trap.

TO define the science of photo‐elasticity we need but say that, with the aid of certain optical equipment, it enables us to see the pattern of stress simultaneously over the entire extent of a scale model under test. If desired, the pattern may be seen in all the delicate hues of the spectrum, but for exact analytical measurement it is sometimes preferable to obtain the sharp‐edged black and white tracing by means of monochromatic light. We might with reason add that the pattern so depicted is complete down to the last detail and represents, in many cases, a unique solution of a complex mathematical problem in elastic deformation. Its application to mechanical engineering design has been widespread and is still reaching out into new fields. By its use it is now possible to trace and measure the intensity and internal distribution of stress in loaded components far more speedily and accurately than can be achieved by any other method.

Describes the benefits that arise from the use of Light Emitting Diodes (LEDs) for illumination in industrial machine vision systems. These include long life, stability and narrow frequency bands. Also discusses precautions that need to be taken for obtaining a uniform illumination and pulsed operation.