Ordinary Illumination Research Articles

Light-field modulation and optimization near metal nanostructures utilizing spatial light modulators

Abstract Plasmonic modes within metal nanostructures play a pivotal role in various nanophotonic applications. However, a significant challenge arises from the fixed shapes of nanostructures post-fabrication, resulting in limited modes under ordinary illumination. A promising solution lies in far-field control facilitated by spatial light modulators (SLMs), which enable on-site, real-time, and non-destructive manipulation of plasmon excitation. Through the robust modulation of the incident light using SLMs, this approach enables the generation, optimization, and dynamic control of surface plasmon polariton (SPP) and localized surface plasmon (LSP) modes. The versatility of this technique introduces a rich array of tunable degrees of freedom to plasmon-enhanced spectroscopy, offering novel approaches for signal optimization and functional expansion in this field. This paper provides a comprehensive review of the generation and modulation of SPP and LSP modes through far-field control with SLMs and highlights the diverse applications of this optical technology in plasmon-enhanced spectroscopy.

Growth and cell cycle of Ulva compressa (Ulvophyceae) under LED illumination.

The cell-cycle progression of Ulva compressa is diurnally gated at the G1 phase in accordance with light-dark cycles. The present study was designed to examine the spectral sensitivity of the G1 gating system. When blue, red, and green light-emitting diodes (LEDs) were used for illumination either alone or in combination, the cells divided under all illumination conditions, suggesting that all colors of light were able to open the G1 gate. Although blue light was most effective to open the G1 gate, red light alone or green light alone was also able to open the G1 gate even at irradiance levels lower than the light compensation point of each color. Occurrence of a period of no cell division in the course of a day suggested that the G1 gating system normally functioned as under ordinary illumination by cool-white fluorescent lamps. The rise of the proportion of blue light to green light resulted in increased growth rate. On the other hand, the growth rates did not vary regardless of the proportion of blue light to red light. These results indicate that the difference in growth rate due to light color resulted from the difference in photosynthetic efficiency of the colors of light. However, the growth rates significantly decreased under conditions without blue light. This result suggests that blue light mediates cell elongation and because the spectral sensitivity of the cell elongation regulating system was different from that of the G1 gating system, distinct photoreceptors are likely to mediate the two systems.

Optimization of the visibility of graphene on poly-Si film by thin-film optics engineering

A multilayer optical system containing poly-Si film, SiO2 film, and Si substrate (poly-Si substrate) has been designed to enhance the visibility of graphene in contact with poly-Si. Film thicknesses of poly-Si and SiO2 have been optimized by parametric study of the integral contrast of single layer graphene using transfer matrix theory. The multilayer poly-Si substrate and the most commonly used 285 nm SiO2/Si substrate (SiO2 substrate) have been fabricated. Graphene grown by chemical vapor deposition on Ni catalyst has been transferred to the substrates and the visibility of the graphene on the different substrates has been compared. The samples have been characterized by optical microscope, illuminated with light from halogen lamp, and/or filtered with a 600 nm narrow band optical filter. The contrast of graphene on poly-Si substrate has been increased to near 8.7% under 600 nm narrow band illumination from nearly invisible under ordinary illumination, while the contrast of graphene on SiO2 remains almost the same. Raman spectroscopy has been used to verify the presence of the single layer graphene on the poly-Si substrate.

Effect of Reduced Illumination on Insomnia in Office Workers

We evaluated the possible effects of reduced illumination in the workplace on insomnia among office workers. Seventy-two office workers answered the Athens Insomnia Scale (AIS) in July 2009 (under ordinary illumination, 01 conditions) and July 2010 (under reduced illumination, Rl conditions). The workers were divided into three groups, indoor workers (IWs), semi-outdoor workers (SWs) and outdoor workers (OWs), according to the frequency of working outside of the office because a worker with a high frequency of working outside of the office might rarely be exposed to the lighting condition within an office. The first five items of the AIS (AIS-5) were used to assess sleep difficulties, and the last three items (AIS-3) assessed next-day consequences of sleep or daytime symptoms, which often result from insomnia and/or sleep disorders. Illuminance levels at a height of 1,100 mm from the floor under the Rl conditions (550-490 lux) were significantly lower than under the Ol conditions (750-700 lux). The AIS-5 score of the IWs was significantly increased under the Rl conditions compared with the Ol conditions. There was no difference in AIS-3 scores between conditions for any group. Indoor workers hardly went outside of the office and were exposed only to office light during the daytime. Thus, the underexposure to light could have had an impact on insomnia in those individuals. A novel lighting environment is required to optimize work-related levels of light exposure.

An efficient way of high-contrast, quasi-3D cellular imaging: Off-axis illumination

An imaging system enabling a convenient visualisation of cells and other small objects is presented. It represents an adaptation of the optical microscope condenser, accommodating a built-in edge (relief) diaphragm brought close to the condenser iris diaphragm and enabling high-contrast pseudo-relief (quasi-3D) imaging. The device broadens the family of available apparatus based on the off-axis (or anaxial, asymmetric, inclined, oblique, schlieren-type, sideband) illumination. The simplicity of the design makes the condenser a user-friendly, dedicated device delivering high-contrast quasi-3D images of phase objects. Those are nearly invisible under the ordinary (axial) illumination. The phase contrast microscopy commonly used in visualisation of phase objects does not deliver the quasi-3D effect and introduces a disturbing ‘halo’ effect around the edges. The performance of the device presented here is demonstrated on living cells and tissue replicas. High-contrast quasi-3D images of cell-free preparations of biological origin (paper fibres and microcrystals) are shown as well.

Influence of Added Astaxanthin Level and Color on Flavor of Pastes of Rainbow Trout

The feasibility of adding astaxanthin as a source of red color directly during processing of rainbow trout pastes was evaluated. The effect of red coloration and astaxanthin concentration (< 35 mg kg-1) on salmon flavor intensity was assessed by flavor ranking, paired comparison and duotriotests by a semitrained panel, using ordinary white light and red illumination. Effects of added astaxanthin level were not consistent. Flavor ranking of pastes with five different astaxanthin concentrations indicated a U-shaped relationship between flavor intensity and astaxanthin concentration. Paired comparison in white light indicated highest salmon flavor in pastes without added astaxanthin. A second flavor ranking and duotrio tests indicated no significant effects of astaxanthin content. The results suggest that astaxanthin may be added during processing of pastes without negatively affecting product flavor.

Photochemical and oxidative degradation of the solid-state tretinoin tocoferil.

The photostability of tretinoin tocoferil was investigated under irradiation with three kinds of lamps, i.e., a cool white fluorescent lamp, a UV-A fluorescent lamp and a D65 fluorescent lamp. A combination of the cool white fluorescent lamp and the UV-A fluorescent lamp, and the D65 lamp having relative spectral power distribution similar to that of direct daylight, correspond to options 2 and 1 in ICH Guidelines, respectively. The photodegradation apparently followed second-order kinetics under these light sources and the degradation rate constant under exposure by the D65 lamp was larger than that by the cool white fluorescent lamp. The drug was susceptible to degradation by visible and UV light below 480 nm and was degraded most remarkably at around 420 nm, showing a wavelength-dependency. The semi-logarithmic plots of apparent degradation rate constant against the reciprocal of illuminance showed a good linear relationship in the Arrhenius-type fashion, and the photostability under ordinary illumination conditions could be predicted from the data obtained under the accelerated illumination conditions. The rate of oxidative degradation was slightly accelerated with the rise of temperature. Thermodynamic parameter was calculated from the Arrhenius plot. The degradation rate constant rapidly increased in proportion to partial pressure of oxygen below 20 kPa.

Stabilization-oriented preformulation study of photolabile menatetrenone (vitamin K 2)

The photostability of menatetrenone in rape seed oil as a solvent was investigated under irradiation with a fluorescent lamp to obtain basic information on encapsulation of the drug. The drug was susceptible to degradation by visible light below 480 nm and was most strongly degraded at around 430 nm, showing wavelength dependency. The degradation followed apparently first-order kinetics for a given initial concentration and exhibited a concentration dependency. The greater the initial concentration, the smaller was the degradation rate constant. Semilogarithmic plots of the apparent degradation rate constant against the reciprocal of illuminance demonstrated a linear relationship similar to that of Arrhenius-type behavior, and prediction of photostability under ordinary illumination conditions was suggested to be possible from the data obtained under conditions of accelerated illumination. Geometrical scale factors relating to the dosage form were also investigated, and it was found that round capsules were the most favorable shape from the viewpoint of stability.

The motor programs of monkey's saccades: an attentional hypothesis.

We analyzed the dynamics of saccadic eye movements performed by monkeys in three different conditions: as a part of an ocular motor task, spontaneously when the monkey was alert but not performing a task in ordinary room illumination, and spontaneously when the monkey was alert but not performing a task in total darkness. We found three general classes of saccades: 1) regular-symmetric, in which the rise time of the velocity profile was equal to the falling time; 2) regular-asymmetric, in which the rise time was less than the falling time; 3) irregular, in which there were multiple velocity maxima or inflection points. The monkeys made irregular saccades half the time in the two spontaneous saccade conditions, and almost never during the task. In order to see if the regularity of saccades was an artifact of reward, we then evoked saccades by presenting the monkeys with novel visual and acoustic stimuli to which they made saccades. Such guided saccades to novel stimuli had regular velocity profiles. We suggest that saccades made as a part of attentive behavior differ in their motor programming from saccades made spontaneously in darkness, or saccades made in the light without a purpose relevant to visual behavior.

Magnification Of Prisms: An Apparent Anomaly And Its Explanation

The magnification of a single prism or a series of prisms is normally considered in a situation when collimated light is incident, which is equivalent to placing the object at a very large distance from the prism system. This is the usual situation considered and described in most of the literature. In such cases, the magnification is referred to as the anamorphic magnification of the prism system in collimated light. However, when the object is at a finite distance, the apparent magnification is quite different and sometimes is just the reciprocal of what it would be if the object were at infinity. These situations are analyzed for the case of Brewster prisms, and the results can be checked visually very easily in ordinary white-light illumination because of the mutual cancellation of the dispersion of the Brewster prisms.

Effect of early light deprivation on acetylcholinesterase activity in the visual cortex.

1. Early light deprivation of animals causes a significant fall in AChE activity in layers III, IV, and V of the visual cortex. The degree of lowering of enzyme activity is practically identical in all these layers of the visual cortex. 2. On recovery of visual function (keeping the visually deprived animals for 2 weeks under conditions of ordinary illumination) AChE activity undergoes appreciable normalization but does not reach the corresponding control levels. 3. The dynamics of changes in AChE activity in the visual cortex during visual deprivation followed by restoration of the specific function is evidence that changes in enzyme activity discovered under deprivation conditions are functionally dependent.

Effects of level of indoor illumination on the judged annoyance of aircraft noise

Annoyance response to 27 recorded aircraft noise stimuli presented at levels ranging from 83.9 to 91.8 dBA (peak value) was measured by magnitude estimation, under three different levels of simulated living room illumination. One level of illumination was ordinary room brightness, and the other levels were either dimmer or brighter. Analyses of variance, performed on the slopes and intercepts of the annoyance function, showed that the illumination conditions were significant. Test/retest and split-half reliabilities indicated the annoyance measures were stable and consistent under the influence of illumination. There was a clear difference in both slope and intercept between dim and ordinary illumination, indicating that the annoyance is less at low noise levels and grows more rapidly with increasing noise level under dim than ordinary illumination. The regression lines of annoyance showed that, relative to ordinary illumination, the annoyance is (1) less under dim (31% annoyance reduction, or 5 dB equivalent attenuation) at an aircraft noise level of about 89 dBA and (2) less under bright (24% annoyance reduction, or 4 dB equivalent attenuation) at about 88 dBA.

Histopathologic findings in surgical specimens of endolymphatic sac in Meniere's disease.

Two types of abnormality in the endolymphatic sac acquired at shunt surgery are presented. One was deep brown pigmentation in the subepithelial connective tissue. The pigment did not react to Prussian blue, thus ruling out hemosiderin. The other, in seven out of eight specimens, was the perisaccular fibrosis. The fibrotic foci in four cases were assumed, from the findings under ordinary illumination and polarized light microscopy, to be reorganized scar tissue.

A simple method for total particle counts of trachoma and inclusion blennorrhoea viruses.

DARK-GROUND illumination has been used to examine the elementary bodies of large viruses in stained and unstained preparations1,2. We find that unstained crude suspensions of chick embryo yolk sacs infected with the viruses of trachoma and inclusion blennorrhœa, examined under dark-ground illumination, contain particulate host material which obscures the virus particles and which can be confused with them. However, when such suspensions are dried, fixed and stained with Giemsa, many bright yellow-green particles are seen by dark-ground illumination, resembling elementary bodies stained with acridine orange and viewed by ultra-violet microscopy. Their colour and intensity clearly distinguish them from background material, even if they are enveloped by it. They resemble virus particles in size and shape, and their distribution in yolk sac smears is the same as that of the purple elementary bodies in films stained by Giemsa viewed by ordinary illumination; they are not present in smears of normal yolk sacs. Our conclusion that these are virus particles is also supported by dark ground microscopy of inclusions found in HeLa cells infected with trachoma or inclusion blennorrhœa viruses3. The inclusions contain numerous yellow-green particles similar to those in yolk sac smears and suspensions. Large forms of virus are also recognizable, but are much less bright, and reddish in colour.

Appendages on the Spores of Myrothecium verrucaria

DURING an investigation on the degradation of cotton by Myrothecium verrucaria it was observed that spores produced by cultures of this fungus showed under the microscope an unexpected appendage or ‘tails’ which is illustrated by Fig. 1, and which, to our knowledge, has not been described previously. This appendage cannot be seen when unstained spores mounted in water are examined under the microscope by ordinary illumination. It is not stained by cotton blue, but is coloured pink with Loeffler's flagella stain and is then clearly visible. When a drop of a spore suspension in water was placed on a microscope slide and allowed to evaporate, it was observed, by phase contrast illumination, that the spores, which had ‘tails’, stuck to that part of the slide from which the water had receded whereas other spores, which appeared to have no ‘tails’, were carried along by the receding water. An electron micrograph confirmed the existence of the ‘tails’, suggesting that they are extremely thin, and fan-shaped. Furthermore, it appeared that the ‘tail’ emerged just to one side of the point of the spore, not from the point itself. From the observations we think it possible that, in water, the appendage might have a conical shape.

An analysis of the illumination technique of Cibis.

Cibis recently published an account of a new technique of illumination for microscopy.¹Figure 1 illustrates some of the major differences between microscopy with transmitted and Cibis illumination. Note how details which are not visible with ordinary illumination suddenly appear, such as zones of discontinuity in the lens. There are also striking color changes in the cornea, iris pigment, and so forth. Subtle color differences appear, for instance between ciliary muscle and surrounding connective tissue. In the present work I have attempted to analyze this method in order to be better able to interpret what is seen, to plan further applications, and to be able perhaps to extend the technique. <h3>The Production of Color</h3> Color in an object is produced by seven basic mechanisms: Light striking an object

Biophysical studies of methods utilizing fluorescein and its derivatives to diagnose brain tumors.

The clinical use of sodium fluorescein as an aid in the diagnosis and localization of brain tumors has been previously documented (6, 11, 14). Briefly, the technic used at the present time is as follows: All patients subjected to craniotomy are injected immediately preceding surgery with 1.0 gram of sodium fluorescein. At operation, the cortex of the brain is examined under ultraviolet light. If a superficial tumor is present, it can be easily distinguished and its limits outlined by the presence of the yellow-green fluorescence typical of fluorescein. If the tumor is below the cortex and gives no indication of its presence on examination and palpation, brain needles are commonly used to probe for it and to obtain biospy material. With singular consistency, the presence or absence of fluorescence of the tissue fragments procured has been indicative of the presence or absence of abnormal tissue. Edematous brain tissue fluoresces slightly, and therefore, even if the surgeon does not strike the tumor directly, its proximity can be predicted by the presence of a slight fluorescence of the biopsy material. If a second biopsy taken from an area adjacent to the first reveals no fluorescence, the surgeon knows that the tumor is in the opposite direction. Among the last 104 patients suspected of having brain tumors in whom the fluorescein method was used, there were 96 with tumors which fluoresced, 8 whose tumors did not fluoresce, 6 who had no tumor and no fluorescent tissue, and only one in whom fluorescence was described and no tumor found. Figure 1 is an operative specimen photographed with ordinary illumination. The tumor, a recurrent astrocytoma, is surrounded by a rim of normal brain tissue. Figure 2 is a photograph of the same specimen exposed to ultraviolet light; the centrally situated tumor tissue is fluorescent in contrast to the peripherally located normal brain tissue. The patient was given one gram of sodium fluorescein (5 per cent solution) one hour before operative removal of the specimen. The 8 tumors which did not fluoresce were 3 diffuse astrocytomas in patients with long histories, 1 angioblastoma which was almost completely necrotic, 1 medulloblastoma, and 3 diagnosed as cholesteatomas. These errors represent the limitations of the procedure. These tumors, with a single exception, were benign and slow-growing. The affinity of fluorescein for tumor tissue is not specific but can be demonstrated in any lesion of the central nervous system which breaks down the so-called “blood-brain-barrier mechanism” (BBB). Thus one would expect, as mentioned previously, that areas of brain edema would fluoresce slightly, as would the capsules of brain abscesses, granulomas, and traumatized tissue. The membranes of subdural hematomas also fluoresce. For the most part, these can be easily distinguished from the more vividly fluorescent neoplastic lesions. Metastatic tumors, regardless of type, fluoresce brilliantly.

Diminution of Acetylcholine Content of Retina After Prolonged Functional Disuse

With aseptic precaution, the eyelids of one of the dog's eyes were sutured together, the other being left untouched as a control. After a period of blindfolding, the lids were opened up under ether anesthesia, the eyeball enucleated, and the retina carefully freed from the ciliary muscle and extracted with alcohol. All these procedures were done in the dark room under red light. The control eye was similarly prepared under ordinary illumination. The acetylcholine (AC) was identified by different tests, and the quantity determined by assay with the toad's rectus preparation.While the AC content of the retina of the eye blindfolded for 7-49 days was found to be 11-25% less than that of the control in 5 experiments, that of the eye blindfolded for 160-170 days was over 58% less than the control in 4 experiments. The variation of the AC content of the retinae of the 2 normal eyes encountered in 12 experiments was 9.3 ± 8.4%.As there was no sign of infection, injury or irritation of any sort in the blindfolded...

ABNORMAL BACTERIAL FLAGELLA

ABSTRACT To the Editor: —In an article entitled Abnormal Bacterial Flagella in Cultures: Their Resemblance to Spirochetes (The Journal, May 1, 1926, p. 1327) I described and pictured various types of detached overgrown bacterial flagella as seen by dark field illumination. This type of illumination brings out forms of extreme thinness not visible by ordinary illumination, the forms that are most readily confused with spirochetes. Since the dark field microscope is extensively used for research on spirochetes, I was concerned chiefly with the appearance of the flagella by dark field, and I omitted to mention that the subject had previously been investigated by bright field and staining methods. I wish to call the attention of those interested in this problem to a paper by Dr. Laura Florence (J. Bacteriol. 6:371 [July] 1921) in which the work on abnormal bacterial flagella as studied by bright field methods is reviewed and extended.

The properties of colloidal systems. IV. —Reversible gelation in living protoplasm

Protoplasm itself, using the name to express living substance in its simplest, undifferentiated form, is generally recognised as having the properties of a somewhat viscous liquid. This fact was realised as long ago as 1864 by Kühne (1864). As usually seen under the microscope, it contains suspended in it a number of granules of a great variety of dimensions and properties. But in the pseudopodia of an amoeba or of a leucocyte, when examined by the ordinary method of illumination with transmitted light, it appears completely devoid of contents or structure. As Hardy (1899) showed, the various networks and similar arrangements seen in fixed preparations are produced by the action of the reagents used, although they indicate that protoplasm contains matter in the colloidal state. The use of the method of brilliant lateral illumination on a dark ground (so-called “ultra-microscope”) has led to the detection of particles in protoplasm which are too minute to be visible by ordinary illumination. Of course, these particles, being comparable in dimensions with the mean wave-length of light, are not seen in their true dimensions or form, but by their diffraction discs. Remembering that the late Lord Rayleigh showed that the more intense the illumination, the more minute are the particles that it is possible to detect, I tested the result of increasing the intensity of the dark-ground illumination applied to the apparently clear and structureless pseudopodia of large amoebae. The broad flat pseudopodia of a species, which appeared to correspond toAmœba princeps(Leidy), were found to be most appropriate for the purpose. A paraboloid condenser, made by Zeiss, was used in most cases. The source of light was the positive crater of a small arc lamp with carbons at right angles to one another. The rays were made parallel by a condenser, and passed through a cell with parallel sides, about 5 cm. apart, before falling on the mirror of the microscope. The water-cell was found to be necessary on account of the heat otherwise transmitted being sufficient to kill the organisms. In order to obviate the injurious effect of any ultra-violet rays which might be transmitted through the system, quinine sulphate was added to the water. The objective used for the majority of the observations was an excellent ⅙-inch dry lens made by Swift, which was found to admit of magnification by fairly high-power oculars, such as No. 12 compensating of Zeiss. Other methods, such as that of an objective as sub-stage condenser, with a central stop in the observing objective to cut out direct rays, were tried; but the paraboloid was found to be the best on the whole.