A Scanning-Spot Interferometer For Measuring Steep Aspherical Surfaces

A single crystal sapphire component has been widely used in various high-tech fields because of its significant advantages such as high hardness, high stability, and excellent optical and mechanical properties, and has put forward high requirements for surface accuracy and quality. The existing sapphire polishing technology has problems such as low polishing efficiency, difficult control of polishing accuracy, and difficulty in removing surface defects and subsurface damage introduced by the front grinding process. Therefore, for the polishing and damage removal stage of sapphire optical components, the surface shape accuracy should be strictly controlled, especially for the surface shape accuracy after ultra-precision grinding. It is of great significance to study the uniform removal technology of grinding damage based on not destroying the surface shape. This study focuses on the mechanical polishing of sapphire. Firstly, the characteristics of the sapphire removal function of the elastic polishing tool are analyzed and the stability of the polishing tool is verified. Secondly, by establishing the relationship between the amount of workpiece material removal and the radius of rotation, the feed rate is planned to achieve the effect of uniform spiral removal. By optimizing the center feed speed of the tilting axis small-size polishing tool, the center feature of the polishing surface is controlled to be sharp. Finally, based on the sub-aperture polishing figuring theory, the influence of the center feature on the surface profile is reduced by using the spiral grating processing method. This study provides an efficient and stable strategy for the uniform removal and polishing of rotationally symmetric optical elements (such as aspheric surfaces) of high-hardness material sapphire and is expected to play a role in scenes that are particularly difficult to process, difficult to detect full aperture, difficult to calculate removal function and dwell time, such as higher steep aspheric surfaces and Gaussian aspheric surfaces.

We report a method for testing small light spot produced by an optical system with high numerical-aperture (NA). A high NA objective was used to converge the incident linear polarized light, and a tapered optical fiber probe with an opening of 50-80 nm mounted in the near-field optical microscopy (SNOM) apparatus was used to measure light intensity. The small light spot can be measured with high spatial resolution. The results show that a resolution of 50~100 nm can be obtained.

Intense pulsed light (IPL) technology has long been used in the treatment of facial telangiectasia. While the large spot size of traditional IPL devices offers rapid coverage, it has limitations in terms of visibility and uniform contact with the skin in contoured areas of the face. The novel IPL used in this study had a small spot size (6.35mm) and shorter wavelength (500-635nm), allowing the use of high fluence without burning the normal epidermal tissue surrounding the lesion, thus providing better efficacy. Treatment of facial telangiectasia using small-spot IPL is effective with a low risk of dermatological damage, and its uses for medical care are expected to diversify.

Previously (This Journal, 1964, 18, 952) we found that the apparent paths of two spots moving independently on straight tracks were perceived as curving lines. This fact suggests that two moving objects have a tendenq to be seen as approaching each other in the distance. Further study of the relation between apparent and objective paths of two moving spots under different conditions was attempted.

1. In the lateral geniculate nucleus (LGN) of 18 kittens whose ages ranged from 6 to 40 days, 445 cells were studied. 2. LGN cells of kittens younger than 21 days are characterized by very low maintained rates, long latencies to full-field flash, response fatigue, large receptive field, absence of surround responses and surround inhibition, poor responses to fast-moving stimuli, and low-amplitude responses to flashing spots. 3. Cells were characterized as sustained or transient, and on, off, or on-off by their responses to flashing spots of light, and as X-like of Y-like by their responses to contrast reversal. Prior to 21 days, cells are hard to classify as X or Y. 4. A large proportion of cells in kitten LGN have both on- and off-responses to small and center-sized spots of light. This proportion decreases with development. 5. A small number of cells develop mature receptive-field properties very early (14--20 days). These are cells with X-type responses (linear summation) to contrast reversal and tend to have sustained responses to flashing spots. 6. Y-like cells, with nonlinear summation, develop mature receptive-field properties later than 34 days of age and later than all X-cells. 7. We conclude that there are different developmental patterns for cells of the kitten LGN. These different patterns may be important in determining the visual responses of cortical cells and their degree of susceptibility to environmental modification.

1. We analyzed the light-evoked responses of retinal neurons by means of a white-noise technique. Horizontal and bipolar cells produced a modulation response that was linearly related to a modulation of the mean luminance of a large field of light. The first-order kernels were capable of reproducing the cells' modulation response with a fair degree of accuracy. The amplitude as well as the waveform of the kernels changed with the change in the mean luminance. This is a parametric change and is a form of field adaptation. As the time constant of the parametric change was much longer than that of the modulation response (memory), neurons were assumed to be at a dynamic steady state at a given mean luminance. 2. With the presence of a steady annular illumination, the first-order kernel derived from stimulation with a small spot of light became faster in peak response time and larger in amplitude. For horizontal-cell somas and bipolar cells, the surround also linearized their modulation response. This surround enhancement has been seen in all the cone-driven retinal cells except the receptor and horizontal cell axon, in which a steady surround decreased the amplitude of the spot-evoked kernel but shortened the peak response time. 3. A change in the modulation depth did not affect either the amplitude or the wave-form of the first-order kernels from the horizontal and bipolar cells. In the amacrine and ganglion cells, on the other hand, the amplitude of kernels was related inversely to the depth of modulation. These cells were more sensitive to the modulation of a small modulation depth. 4. A static nonlinearity appeared when signals were transmitted to the amacrine cells. The nonlinearity was first produced in the type-C amacrine cells by a process, which could be modeled by squaring the bipolar cell response. A gamut of more complex second-order nonlinearities found in type-N amacrine cells could be modeled by a band-pass filtering of the type-C cell response. Linear components in the bipolar cells and nonlinear components in the amacrine cells are encoded into spike trains in the ganglion cells. Thus, under our simple stimulus regimen, the ganglion cells transformed the results of the preganglionic signal processing into a spike train without much modification. 5. We propose a tentative diagram of the signal flow in the cone-driven catfish retinal neurons based on this and previous studies.(ABSTRACT TRUNCATED AT 400 WORDS)

Many persons with low vision have diseases that damage the retina only in selected areas, which can lead to scotomas (blind spots) in perception. The most frequent of these diseases is age-related macular degeneration (AMD), in which foveal vision is often impaired by a central scotoma that impairs vision of fine detail and causes problems with reading and recognizing faces. One would think that differences between damaged and relatively intact areas should be painfully obvious to those who have AMD. However, as clinical practice and scientific studies have shown, this is often not the case (Safran & Landis, 1996, 1999; Schuchard, 1995). Thus, patients and rehabilitation workers need to know where on the retina or in the visual field vision is still good enough to be usable. Having this information increases the chances for successful rehabilitation, the necessity and feasibility of which have been demonstrated (Backman & Inde, 1979; Nilsson, Frennesson, & Nilsson, 2003; Otto, 1969; Park, 1999). The fact that rehabilitation is possible emphasizes the need for a topographic assessment of remaining vision. In this article, I describe the Macular Mapping Test (MMT) and illustrate with case reports how it can be used in clinical practice to assist in the assessment and rehabilitation of patients with central vision loss. THE IDEAL SOLUTION Topographic assessment is best done by a scanning laser ophthalmoscope (SLO) that shows live images of the retina and the stimulus that is scanned directly onto it. A useful vision assessment in AMD does not need to encompass the entire visual field. It can be restricted to the macula, a central area of 20 degrees diameter, where most preferred retinal loci (PRL) develop (Fletcher & Schuchard, 1997). If small spots of light are flashed onto the retina (microperimetry), the patient indicates which are detected and which are not. For precise placement of stimuli, modern software compensates for involuntary eye movements during testing, so that precise fixation is not necessary (MacKeben & Gofen, 2007). Since SLOs are expensive and rare, they are not available to most vision professionals. WHAT OTHER MEANS ARE AVAILABLE? Conventional perimetry can provide relevant data, but it is time-consuming and requires sophisticated equipment and special expertise. In addition, the resulting intensity thresholds are not needed to find usable remaining vision for rehabilitation. The standard tangent screen test has shortcomings in that it makes it hard to include a discrimination (recognition) paradigm for a better measurement of visual performance. Furthermore, it is difficult to time the appearance and disappearance of a target precisely at defined locations, and the results can vary with the examiner's level of skill and personal habits. The Amsler grid is a subjective test that is sensitive only to drastic changes, but not to those that develop over longer periods. At best, it indicates where damage has been done, but not visual performance. In addition, the normal filling-in mechanism often prevents the detection of scotomas of less than 5 degrees diameter (Ramachandran & Gregory, 1991; Schuchard, 1993). [FIGURE 1 OMITTED] Note that measuring visual acuity alone is insufficient, despite the importance of visual acuity for prescribing optical aids, because it has limited utility in predicting the performance of activities of daily living, like reading (Backman, 2000; Crossland, Culham, & Rubin, 2005) or visually guided mobility (Brown, Brabyn, Welch, Haegerstrom-Portnoy, & Colenbrander, 1986; Hassan, Lovie-Kitchen, & Woods, 2002; Marron & Bailey, 1982) after the loss of central vision. Also note that subsets of the data presented here were published previously (MacKeben & Colenbrander, 2000; MacKeben, Colenbrander, & Gofen, 1999). DESCRIPTION OF THE TEST Procedure Although MMT is not new (MacKeben & Colenbrander, 2000; MacKeben et al. …

Synodontis woleuensis, a new species of mochokid catfish, is described from the Woleu/Mbini/Uoro and Ntem basins of Gabon and Equatorial Guinea. This relatively small species (<70 mm SL) is among the few Synodontis species with well-developed serrations along the anterior margin of the dorsal spine. It can further be distinguished from all congeners by a distinctive pigmentation pattern consisting of a dark background with numerous, small and irregular light spots, a pair of light spots anterior and posterior to the adipose fin, and a narrow, depigmented, curved band along the anterior margin of the caudal fin. New taxon: Synodontis woleuensis Friel and Sullivan

Luneburg's model for computation of the curvature K of visual two-dimensional space (horizontal visual surface) was tested with equidistant and parallel alleys in large open spaces. Forty-six subjects used stakes to produce 406 experimental alleys of variable sizes (from 5 x 1 to 240 m x 48m). The results show that, contrary to results obtained under laboratory conditions with small alleys and light spots, the individual curvature of visual space does not have negative constant value. K varies in the interval - 1 to + 1 in ninety computed settings: K greater than 0 (N = 38); K less than 0 (N = 52). Therefore the Lobachevskian gemetry currently attributed to visual space ought to be replaced by a Riemannian geometry of variable curvature. Moreover K is an individual function dependent on the size of the alley (distance from the subject), and visual perception would be better understood as scale-dependent. Independently of Luneburg's model we have tested the constancy of the curvature hypothesis in experiments with horopters and visual triangles. The results obtained invalidate Luneburg's hypothesis also.

Scheffleraoctophylla is widely cultivated in South China due to its highornamental and economic value. In April 2022, a leaf disease on S. octophylla was observed in Zhanjiang (21.20° N, 110.41°E), China. Diseaseincidenceandseverity were 15%and 20% (n = 100 investigated plants), respectively. Symptoms on leaves primarily appeared as small light gray spots, then enlarged and coalesced into regular or irregular light gray necrotic lesions with dark margins. Ten symptomatic leaves from 10 plants were collected. Small pieces of tissue (4 × 4 mm) were cut from lesion borders and were surfaced disinfected in 75% ethanol for 30 s, followed by 1 min in 1% NaClO, rinsed three times with sterile water, plated on potato dextrose agar (PDA), and incubated at 28°C. After 5 days, fifteen morphologically similar fungal isolates were obtained from all 10 leaf samples and three representative strains (YZM-1, YZM-2, and YZM-3) were used for morphological and molecular characterization.Colonies were white with cottony aerial mycelium. After 10 days, black viscous acervuli were scattered on the colony surface. Conidia were clavate to fusiform, four-septate, straight or slightly curved, and measured 17.57-25.70 × 4.53-6.80μm (mean 23.13 × 5.14μm) in size (n = 50). Basal and apical cells were colorless while the three medium cells were dark brown and versicolor. Conidia had a single basal appendage (4.5 to 5.5 μm long;n= 50) and two or three apical appendages (18.2 to 33.5 μm long;n= 50). These morphological characteristics were consistent with the description of Neopestalotiopsis clavispora (Maharachchikumbura et al. 2012). For further identification, genomic DNA was extracted by the 2% CTAB method (Lu et al. 2012). The internal transcribed spacer (ITS) region and β-tubulin 2 (tub2) and translation elongation factor 1-alpha (tef1α) genes were amplified using the primers ITS1/ITS4, T1/Bt-2b, and EF1-728F/EF-2 respectively (Maharachchikumbura et al. 2012). The ITS (OM721785-87), tub2 (OQ130413-15) and tef1α (OM810189-91) sequences were 99.38%, 99.33%, and 99.17% identical to the N.clavispora type strain MFLUCC12-0281 (accession nos. JX398979, JX399014, and JX399045, respectively). A phylogenetic tree was generated using the concatenated sequences of ITS, tub2, and tef1α. All three isolates clustered with N.clavispora strains including the type MFLUCC12-0281. For pathogenicity tests, 2-year-old S. octophylla plants (n=10) were sprayed with a conidial suspension (105conidia/ml) on the surface of wounded leaves. Mock-inoculated controls (n=10) were sprayed with sterile distilled water. All plants were wrapped in polyethylene bags for 24 h and incubated at 28°C in a growth chamber at 90% relative humidity. After 10 days, all inoculated leaves showed similar symptoms to those observed in the field, whereas control leaves were asymptomatic. N. clavispora was re-isolated from the lesions and the identity of the fungus was confirmed based on morphology and molecular characterization. The pathogenicity test was repeated three times with similar results. N.clavispora has been reported to cause diseases in a broad range of hosts (Chen et al. 2018; Borrero et al. 2018), but not inS.octophylla. This is the first report of N. clavispora causing leaf blight on S.octophylla in China.Damage caused by N. clavispora could cause significant economic losses if not managed. More research is needed to better understand this disease and establish control strategies.

A new species of Amolops is described from a mountainous area of southern Yunnan Province, China. The species is unique in having a dark purple dorsum with small light yellow spots. The spots are smaller than the smallest finger disk. Other characters that distinguish this species from other species of Amolops include smooth skin (lacking tubercles) over the entire body and lack of dorsolateral folds, transverse bars on the legs, and a visible pineal body.

The paper reviews advanced process for manufacturing high-precision optical components used in space-based electrooptic systems for scientific research and Earth remote sensing. It presents an integrated process for automatic shaping (TESAF) of aspheric surfaces, including off-axis surfaces, of optical elements for electrooptic systems. This paper discusses various methods for shaping optical parts with virtually any degree of asphericity and various values of the off-axis parameter (off-axis aspherics) achieving surface shape precision to within λ/60…λ/80 (λ = 0.6328 micron) by the standard deviation criteria. The paper also presents the newly developed off-axis collimators, designed to shape a reference wavefront within a broad spectral range from ultraviolet to infrared radiation. In particular, a mirror collimator with an adaptive off-axis mirror that is capable of changing the wavefront that is being formed in order to obtain the response function of the electrooptical system under study. Optical systems built using the TESAF process are already successfully used. Key words: surface shaping, aspheric surface, surface interferogram, standard deviation.

Scanning small spots of laser light allows mapping of synaptic circuits in brain slices from transgenic mice expressing channelrhodopsin-2 (ChR2). These light spots photostimulate presynaptic neurons expressing ChR2, while postsynaptic responses can be monitored in neurons that do not express ChR2. Correlating the location of the light spot with the amplitude of the postsynaptic response elicited at that location yields maps of the spatial organization of the synaptic circuits. This approach yields maps within minutes, which is several orders of magnitude faster than can be achieved with conventional paired electrophysiological methods. We have applied this high-speed technique to map local circuits in many brain regions. In cerebral cortex, we observed that maps of excitatory inputs to pyramidal cells were qualitatively different from those measured for interneurons within the same layers of the cortex. In cerebellum, we have used this approach to quantify the convergence of molecular layer interneurons on to Purkinje cells. The number of converging interneurons is reduced by treatment with gap junction blockers, indicating that electrical synapses between interneurons contribute substantially to the spatial convergence. Remarkably, gap junction blockers affect convergence in sagittal cerebellar slices but not in coronal slices, indicating sagittal polarization of electrical coupling between interneurons. By measuring limb movement or other forms of behavioral output, this approach also can be used in vivo to map brain circuits non-invasively. In summary, ChR2-mediated high-speed mapping promises to revolutionize our understanding of brain circuitry.

In this paper is presented a method for computing, and an experimental procedure for verifying, the coupling of a signal, caused by a modulated laser beam, to a load impedance terminating a coaxial waveguide whose center conductor protrudes into a an open-ended body of revolution (BOR).The excitation is the signal radiated by electrons emitted from the conducting surface by an impinging laser beam, modulated in such a way that the electrons escaping the surface oscillate harmonically in time causing them to radiate a coherent signal at an angular frequency ω.For a vanishingly small spot of laser light on the conducting surface, the radiating source is modeled as an electric dipole normal to and located at the surface.To perform this computation directly is very difficult so we resort to an indirect method that allows us to realize significant savings with no loss in generality.The indirect approach adopted here takes the advantage of the reciprocity and allows one to determine the received signal at the coax terminal load from knowledge of the field radiated by a small wire probe mounted on the symmetry axis of the BOR under the condition that the excitation results from a current generator impressed at the terminal end of the coax.This scheme necessitates the formulation and solution of a simpler integral equation.In principle, the approach developed to solve this problem is exact and rigorous.The validity of this approach is demonstrated numerically and experimentally.

Measuring chemical concentrations at the surface of implantedmedicaldevices is important for elucidating the local biochemical environment,especially during implant infection. Although chemical indicator dyesenable chemical measurements in vitro, they are usually ineffectivewhen measuring through tissue because the background obscures thedye signal and scattering dramatically reduces the spatial resolution.X-ray excited luminescent chemical imaging (XELCI) is a recent imagingmodality which overcomes these limitations using a focused X-ray beamto excite a small spot of red light on scintillator-coated medicalimplants with well-defined location (because X-rays are minimallyscattered) and low background. A spectrochemical indicator film placedover the scintillator layer, e.g., a polymer film containing pH-indicatordyes, absorbs some of the luminescence according to the local chemicalenvironment, and this absorption is then detected by measuring thelight intensity/spectrum passing through the tissue. A focused X-raybeam is used to scan point-by-point with a spatial resolution mainlylimited by the X-ray beam width with minimum increase from X-ray absorptionand scattering in the tissue. X-ray resolution, implant surface specificity,and chemical sensitivity are the three key features of XELCI. Here,we study spatial resolution using optically absorptive targets. Forimaging a series of lines, the 20–80% knife-edge resolutionwas ∼285 (±15) μm with no tissue and 475 ±18 and 520 ± 34 μm, respectively, through 5 and 10 mm thicktissue. Thus, doubling the tissue depth did not appreciably changethe spatial resolution recorded through the tissue. This shows thepromise of XELCI for submillimeter chemical imaging through tissue.