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This paper presents the research on the quality of prints obtained with the Xerox DocuColor® 252 and Xerox® Color 1000 graphics systems. The values for optical density, spectral curve as well as CIELab values were measured for samples printed on substrates of different surface masses (150 g/m², 200 g/m², 300 g/m²). A detailed analysis of the measured and calculated values led to the conclusion that the difference in color and thus quality is obvious.

A knowledge of the spectral sensitivities of the long-wavelength-sensitive (L-), middle-wavelength-sensitive (M-) and short-wavelength-sensitive (S-) wavelength-sensitive cone types is vital for modelling human color vision and for the practical applications of color matching and color specification. After being agnostic about defining standard cone spectral sensitivities, the Commission Internationale de l’ Eclairage (CIE) has sanctioned the cone spectral sensitivity estimates of Stockman and Sharpe (2000) and the associated measures of luminous efficiency (Sharpe et al., 2005, 2011) as ‘physiologically relevant’ standards for color vision (CIE, 2006, 2015). These can be used to model mean normal color vision at the photoreceptor level and postreceptorally. Both LMS and XYZ versions have been defined for 2-deg and 10-deg vision. Built into the standards are corrections for individual differences in macular and lens pigment densities, but individual differences in photopigment optical density and the spectral position of the cone photopigments can also be accommodated (Stockman and Sharpe, 1999; Brainard and Stockman, 2010). Understanding the CIE standard and its advantages is of current interest and importance.

A handheld, standalone optical instrument was developed for the in-vivo assessment of the eye’s macular pigment optical density. The instrument is based on the reflectometry method, where the retina is illuminated with light of the appropriate spatial, temporal, and spectral characteristics and the reflected light from the fundus is collected using a high-speed photodetector. The collected light is then analysed and the corresponding value for macular pigment in the eye is computed.

A surgical microscope is large in size, which makes it impossible to be portable. The distance between the surgical microscope and the observation tissue is 15–30 cm, and the adjustment range of the right and left of the camera is a maximum of 30°. Therefore, the surgical microscope generates an attenuation (above 58%) of irradiation of the optical source owing to the long working distance (WD). Moreover, the observation of tissue is affected because of dazzling by ambient light as the optical source power is strong (55 to 160 mW/cm2). Further, observation blind spot phenomena will occur due to the limitations in adjusting the right and left of the camera. Therefore, it is difficult to clearly observe the tumor. To overcome these problems, several studies on the handheld surgical microscope have been reported. In this study, a compact pen-type probe with a portable surgical microscope is presented. The proposed surgical microscope comprises a small and portable pen-type probe that can adjust the WD between the probe and the observed tissue. In addition, it allows the adjustment of the viewing angle and fluorescence brightness. The proposed probe has no blind spots or optical density loss.

We present results of developing metrological assurance for the measurements of the optical density of an X-ray image based on a set of optical density measures in the range of 0.2 to 6.3. The set has been designed to render one unit of diffuse optical density for densitometers used to measure optical density and estimate the size of defects on X-ray images when inspecting nuclear power facilities, oil and gas enterprises, railway transport, metallurgical and mechanical-engineering plants, etc. Results of calibrating the set of optical density measures with the GET 206-2016 State Primary Standard of the unit of optical density, developed and in operation at VNIIOFI, are presented.

Optical masks are classified based on the transmittance of the absorber. The optical density of binary masks is over three. This means that the transmittance is less than 0.1 %. Long experience in developing optical phase-shift masks (PSMs) has shown that the optimum transmittance of PSMs is 5~15 %. High transmittance PSMs are avoided due to the unwanted sidelobe printing. In the same way, EUV masks can be classified based on the reflectance of the absorber. Assuming the phase-shift value of the absorber to be π, the reflectance relative to ML is calculated by exp(-2πk/(1-n)), where n+ik is the complex refractive index of the absorber. Therefore, EUV masks are classified by the ratio of the complex refractive index k/(1-n). We classify EUV masks into four categories, i) binary mask: 1 < k/(1-n), ii) low-R PSM: 0.5 < k/(1-n) < 1, iii) PSM: 0.3 < k/(1-n) < 0.5, and iv) high-R PSM: k/(1-n) < 0.3. Conventional TaN absorber is a low-R PSM where k/(1-n) = 0.58. It is not a binary mask as it requires black borders. The benefit of PSMs is that they reduce dose. The drawback of PSMs is that they increase edge placement error (EPE). Especially in high NA optics, the error cannot be compensated by illumination optimization. On the other hand, binary masks reduce EPE at the expense of increased dose. There is a tradeoff between dose and EPE. The optimum absorber selection depends on the pattern layout. In CH applications, PSMs are favorable to reduce dose. Binary masks are suitable for L/S applications to suppress EPE.

Macular pigment is a yellowish pigment of purely dietary origin, which is thought to have a protective role in the retina. Recently, it was linked to age-related macular degeneration and improved visual function. In this work, we present a method and a corresponding optical instrument for the rapid measurement of its optical density. The method is based on fundus reflectometry and features a photodetector for the measurement of reflectance at different wavelengths and retinal locations. The method has been tested against a commercially available instrument on a group of healthy volunteers and has shown good correlation. The proposed instrument can serve as a rapid, non-midriatic, low-cost tool for the measurement of macular pigment optical density.

Macular pigments (MPs), by absorbing potentially toxic short-wavelength (400–500 nm) visible light, provide protection against photo-chemical damage thought to be relevant in the pathogenesis of age-related macular degeneration (AMD). A method of screening for low levels of MPs could be part of a prevention strategy for helping people to delay the onset of AMD. We introduce a new method for assessing MP density that takes advantage of the polarization-dependent absorption of blue light by MPs, which results in the entoptic phenomenon called Haidinger’s brushes (HB). Subjects were asked to identify the direction of rotation of HB when presented with a circular stimulus illuminated with an even intensity of polarized white light in which the electric field vector was rotating either clockwise or anti-clockwise. By reducing the degree of polarization of the stimulus light, a threshold for perceiving HB (degree of polarization threshold) was determined and correlated (r 2 0.66) to macular pigment optical density assessed using dual-wavelength fundus autofluoresence. The speed and ease of measurement of degree of polarization threshold makes it well suited for large-scale screening of macular pigmentation.

To visualize the existence of micro-calcifications in mammography there are a number of ways carried out including by the magnification technique. This study evaluates the effect of magnification technique on optical density (OD) and size of the objects of the image produced on mammography. The objects used were three circular coins. Source to image distance (SID) was 65 cm, with a focal spot size of 0.1 cm, a combination of targets/filters was Mo/Mo with a filter’s thickness of 30 µm. The tube loading was 100 mAs, the tube voltage was 27 kVp, and the magnification was in the range of 1.00 - 2.00 times with an increase of 0.25. Measurement of OD and size of the objects was using an ImageJ software. The results of this study revealed that the OD value decreases proportional to the magnification. The OD values calculated on the 2x magnification were 13.74, 14.26, and 13.44% lower than 1.0 magnification (without magnification), while the resulting image will be oval in proportion to the position of the coin from the chest wall and the magnification. An implementation of the magnification method in the mammography must be carried out with caution. In addition to a benefit to larger appear of micro-calcification, it also causes a decrease in OD and distortion of objects in the image.

Purpose This study evaluated the summed measures of macular pigment optical density (MPOD) spatial distribution and their effects on intraocular scatter using a commercially available device (C-Quant, Oculus, USA). Methods A customized heterochromatic flicker photometer (cHFP) device was used to measure MPOD spatial distribution across the central 16° using a 1° stimulus. MPOD was calculated as a discrete measure and summed measures across the central 1°, 3.3°, 10° and 16° diameters. Intraocular scatter was determined as a mean of 5 trials in which reliability and repeatability measures were met using the C-Quant. MPOD spatial distribution maps were constructed and the effects of both discrete and summed values on intraocular scatter were examined. Results Spatial mapping identified mean values for discrete MPOD [0.32 (s.d. = 0.08)], MPOD summed across central 1° [0.37 (s.d. = 0.11)], MPOD summed across central 3.3° [0.85 (s.d. = 0.20)], MPOD summed across central 10° [1.60 (s.d. = 0.35)] and MPOD summed across central 16° [1.78 (s.d. = 0.39)]. Mean intraocular scatter was 0.83 (s.d. = 0.16) log units. While there were consistent trends for an inverse relationship between MPOD and scatter, these relationships were not statistically significant. Correlations between the highest and lowest quartiles of MPOD within the central 1° were near significance. Conclusions While there was an overall trend of decreased intraocular forward scatter with increased MPOD consistent with selective short wavelength visible light attenuation, neither discrete nor summed values of MPOD significantly influence intraocular scatter as measured by the C-Quant device.

Radiochromic film has become an important tool to verify dose distributions for intensity‐modulated radiotherapy (IMRT) and quality assurance (QA) procedures. A new radiochromic film model, EBT3, has recently become available, whose composition and thickness of the sensitive layer are the same as those of previous EBT2 films. However, a matte polyester layer was added to EBT3 to prevent the formation of Newton's rings. Furthermore, the symmetrical design of EBT3 allows the user to eliminate side‐orientation dependence. This film and the flatbed scanner, Epson Perfection V750, form a dosimetry system whose intrinsic characteristics were studied in this work. In addition, uncertainties associated with these intrinsic characteristics and the total uncertainty of the dosimetry system were determined. The analysis of the response of the radiochromic film (net optical density) and the fitting of the experimental data to a potential function yielded an uncertainty of 2.6%, 4.3%, and 4.1% for the red, green, and blue channels, respectively. In this work, the dosimetry system presents an uncertainty in resolving the dose of 1.8% for doses greater than 0.8 Gy and less than 6 Gy for red channel. The films irradiated between 0 and 120 Gy show differences in the response when scanned in portrait or landscape mode; less uncertainty was found when using the portrait mode. The response of the film depended on the position on the bed of the scanner, contributing an uncertainty of 2% for the red, 3% for the green, and 4.5% for the blue when placing the film around the center of the bed of scanner. Furthermore, the uniformity and reproducibility radiochromic film and reproducibility of the response of the scanner contribute less than 1% to the overall uncertainty in dose. Finally, the total dose uncertainty was 3.2%, 4.9%, and 5.2% for red, green, and blue channels, respectively. The above uncertainty values were obtained by minimizing the contribution to the total dose uncertainty of the film orientation and film homogeneity. PACS number(s): 87.53.Bn

This study presents diagnostic development of diffuse backilluminated extinction imaging of soot. The method provides high temporal and spatial resolution of the line-of-sight optical density of soot (KL) in compression-ignited fuel sprays relevant to automotive applications. The method is subjected to two major sources of error, beam steering effects and broadband flame luminosity effects. These were investigated in detail in a direct injection combustion chamber with diesel fuel, under high and low sooting conditions. A new method for correcting flame luminosity effects is presented and involves measuring the flame luminosity using a separate high-speed camera via a beam splitter. The new method and existing methods are applied and the resulting flame luminosity correction errors are compared. The new method yields 50% lower errors than the most promising method (optical flow method). The impact on KL was investigated, showing that the KL uncertainty when using the optical flow method is unbounded for KL values above 2.7, while the new method has an uncertainty of 0.5 for the maximum KL value of 3.8. The new method yields overall lower uncertainties and is more suited to measuring KL in optical thick conditions. Large refractive index gradients in the path of the incident light cause false attenuation, resulting in ambiguity of the measured KL, referred to as beam steering. A detailed investigation of the beam steering effects caused by the non-uniformities in the diffused light source was performed. A beam steering model was made and qualitatively validated from experiments. The results from the beam steering model showed the importance of having a large collection angle, in order to average out small-scale non-uniformities in the light source. The model also showed that large-scale non-uniformities in the light source could affect the measurement even if the collection angle is large.

In Boron Neutron Capture Therapy (BNCT) research, information on spatial distribution and concentration of boron in tissues is essential for the treatment planning and for dose determination. Neutron autoradiography technique offers the possibility to gain insight into boron biodistribution in tissues. The irradiation of tissue sections deposited on nuclear track detectors produces damages in the latter, which can be visualized by microscope imaging and that are spatially correlated with the boron localization in the biological section. We had previously developed a methodology for the quantification of boron concentration in tissue samples by nuclear track density determination (QTA). In this work we analyzed the optical density (OD) in autoradiographic images where track density is too high to be quantified by track counting. OD was determined from grey level measurements on low magnification micrographs and proved to be a suitable parameter to quantify boron concentration. The images were originated by placing polycarbonate detectors in contact with samples containing 10B atoms, irradiated with thermal neutrons and finally chemically attacked. Reference standards were developed from aqueous solutions prepared with known boron concentrations in order to construct calibration curves. The obtained optical density values were compared with curves proposed by other authors, showing similar tendencies. The calibration curve was used to make preliminary boron concentration determinations in histological tissue sections of animals infused with boron compounds, which agreed with measurements realized by the QTA approach. The methodology proposed in this work would allow a fast preliminary analysis of histological and autoradiographic images in samples of interest for BNCT. Fil: Vidal, C.. Universidad Favaloro. Facultad de Ingeniería y Ciencias Exactas y Naturales; Argentina Fil: Portu, Agustina Mariana. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Thorp, Silvia Inés. Comisión Nacional de Energía Atómica; Argentina Fil: Curotto, Paula. Comisión Nacional de Energía Atómica; Argentina Fil: Pozzi, E.. Comisión Nacional de Energía Atómica; Argentina Fil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina

Q1. Optical density is: A. The ratio of incident light to transmitted light in logarithmic form B. Measured using densitometer C. A measure of the degree of film darkening D. Referred as radiographic density E. 1.0 if 100% of the incident light is transmitted

A1. Optical density is: A. True. Optical density (OD) = log10 (I0/II) where I0 is the incident light intensity and I is the transmitted light intensity. B. True. Densitometer is a tool to measure OD. OD is often measured for film. C. True. The film is darker with higher OD value. D. True. Radiographic density is also known as OD. E. False. Optical density is 0 if 100% of light is transmitted, 100/100 = 1, log 1 = 0.

In this work, we report on a novel approach for measuring the dose absorbed by the EBT3 Gafchromic™ films exposed to 1 MeV electron beam and 250 kV X-rays in the range 0.5–100 Gy. Although EBT3 is specifically designed to obtain best performance for applications where the maximum dose is less than 10 Gy, there are certain clinical applications requiring dose ranges well above this value. In order to cover wider dose ranges, further models characterized by a thinner sensitive layer and/or different chemical composition have been released. Another method exploiting the three-channel flatbed scanner to delay the saturation point of EBT3 has been also reported. The technique proposed here, aimed at extending the sensitivity of the EBT3 film to high doses up to 100 Gy while ensuring a low dose uncertainty, is based on a broadband analysis of the absorption spectrum of the film in response to irradiation. By combining a wavelength-based approach with the monitoring of two characteristic peaks of the EBT3 absorption spectrum, we demonstrated the capability of measuring the dose in the range 0.5–100 Gy with an experimental uncertainty below 4% for doses lower than 5.52 Gy and below 2% for higher dose levels. Finally, through a dynamic fitting procedure integrating the two aforesaid approaches, a total uncertainty lower than 4%, including both the experimental and fitting errors, was achieved in the whole range 0.5–100 Gy. These results are promising in view of a potential application of this technique in the field of clinical dosimetry at high dose levels.

In this study, optical and thermophysical properties of Gafchromic HD-V2 films are investigated. Gafchromic HD-V2 films have been irradiated with electron and photon sources indifferent doses (0–8 Gy). The optical properties of the irradiated films have been examined using an optical scanner and UV–vis spectrophotometer. The thermophysical properties were studied using a photoacoustic spectrophotometer. It is found that the optical density has increased linearly as the dose increases up to 8 Gy. The thermal diffusivity shows similar behavior as the dose increases. An enhancement of 35% is achieved as the dose increases from 0 to 8 Gy from 12 MeV electron beam source. Keywords: Gafchromic HD-V2, Photoacoustic, Thermal diffusivity, Optical properties

EBT2 film is a convenient dosimetry quality-assurance (QA) tool with high 2D dosimetry resolution and a self-development property for use in verifications of radiation therapy treatment planning and special projects; however, the user will suffer from a relatively higher degree of uncertainty (more than ±6% by Hartmann et al. [29] ), and the trouble of cutting one piece of film into small pieces and then reintegrating them each time. To prevent this tedious cutting work, and save calibration time and budget, a dose range analysis is presented in this study for EBT2 film calibration using the Percentage–Depth–Dose (PDD) method. Different combinations of the three dose ranges, 9–26 cGy, 33–97 cGy and 109–320 cGy, with two types of curve fitting algorithms, film pixel values and net optical densities converting into doses, were tested and compared. With the lowest error and acceptable inaccuracy of less than 3 cGy for the clinical dose range (9–320 cGy), a single film calibrated by the net optical density algorithm with the dose range 109–320 cGy was suggested for routine calibration.

The research finds out some existing certain regularity, and further revises the formulaD=D∞(1-e-ml). The formula means the relationship between ink thickness and ink in density. By using the formal of one-color ink thickness and ink density, the second density that correspond the first major density is transferred to the equal thickness. Then they are added together. According to the formula the real ink density is calculate. Then use the above formula to work out ink thickness. In this way, overprint densities come out, and make contrast with the actual measure data, so the new model formula is built up. The result shows that the average error between the overprint density calculated by ink thickness and the actual measure data is about 0.07. However, the average error between the calculated density using the simple adding method and the actual measure data is about 0.5, so this method is practical and more accurate.

Beer’s law describes the diminution in intensity as light passes through an absorbing medium. Photometry, the primary application of the law in chemistry, is used to deduce the concentration of a light-absorbing component from the decrease in the intensity of monochromatic radiation during passage through a known length of the medium. This article describes the history and nomenclature of the law, as well as its mathematical basis. It goes on to show how the law becomes modified if the absorbing species not only absorbs the light but is also slowly destroyed by it. An intriguing feature is that the same function—the so-called “bleaching function”—describes not only the way in which the light intensity declines with distance, but also the dependence of concentration on time.

Commercial DinoLite AD413 digital microscope was modified for skin diagnostics purposes. The original LED ring (4 white and 4 ultraviolet light emitters) of microscope was replaced by a custom-designed 16-LED ring module consisting of four LED groups (450, 545, 660 and 940 nm), and an onboard LED controller with USB hub was added. The video acquisition and LED switching are performed using custom-designed Matlab software which provides real-time spectral analysis of multi-spectral images and calculation of skin chromophore optical density. The developed multispectral video-microscope is mainly meant for diagnostics of skin malformations, e.g. skin cancerous lesions.

The article discusses the physical processes in a flowing fluid that affect the change in its optical density. Changes in the refractive index and its errors in single-component and multicomponent media for different fluid flow regimes are investigated. A new model has been developed for calculating error of refractive index, considering the non-uniformity of optical density in a stream liquid. A technique is proposed for selecting a refractometer model for reliable monitoring the state of liquid environment.

The main factors responsible for measurement errors in the determining of the refractive index of the flowing fluid are considered. It was found, that the most significant effect on the measurement error have changes in optical density and temperature of the investigated flowing fluid, scattering of radiation in cuvette transducer and wedge shape of the cuvette glass. A new design of differential refractometer has been developed to study the influence of the optical density values of the flowing fluid on the measurement errors. The results of experimental studies are presented.

We demonstrate an electrochromic device (ECD) with high optical density and fast response time. The fabricated ECD shows an optical density of 1.7 at 600 nm and the fastest response time of 1.4 sec. The ECD with a transparent OLED panel exhibits a transmittance of 62.9 % at 550 nm. The transmittance of transparent OLED panel is 68.5% at 500 nm.

Interference filters have improved over the years. Sharp spectral edges (> 1 db/nm) reach high optical density (OD > 8) in a few nm. In-situ optical monitoring to within 0.1% error enables these levels of performance. Due to limitations related to f-number and resolution bandwidth, post-deposition testing in typical spectrophotometers cannot reveal the quality of today's filters. Laser based measurements at selected wavelengths prove that blocking above OD8 to OD9 is manufacturable with high yield. This paper compares modeled spectra and laser based measurements.

A newly released processless Gafchromic EBT3 film was investigated for its response to ultraviolet radiation (UVR) at three different wavelengths: 365 (UVA), 302 (UVB) and 254 nm (UVC). The change in the film's optical density was dependent on the radiance exposure and UV wavelength and was found to correlate with the UV intensity. The dynamic range of the EBT3 films is ∼5 to ∼60 J/cm2 for UVA and UVB and ∼5 to ∼300 J/cm2 for UVC. The dose sensitivity of EBT3 films for UVA and UVB radiation was approximately 10 times higher than that for UVC radiation. The results indicate the suitability of EBT3 films for quantitative and qualitative measurements of UVR exposure.

value of absorption of light energy is dependent on the number of molecules present in absorbing material and the thickness of the medium. Thus, intensity of light energy leaving the absorbing substance is used as an indication of concentration of that particular substance. If the thickness i.e. path length of the light energy in the sample holder, normally the flow through cell and intensity of incident light energy are kept constant, then the amount of light energy transmitted out of the absorbing media is proportional to the concentration of the media. Usually the transmitted light energy and concentration are related to Lambert's and Beer's law of photometry. However, the Lambert's and Beer's law of photometry is valid or linear up to the optical density of 2.0. In the presented work, it is proposed to facilitate the Lambert's and Beer's law of photometry to go beyond optical density of 2.0 and measure the concentrations of sample at high value.

We have investigated the properties of polymethine dyes (PMD) and the purpose of using them as sensors of hazardous gases presence. Research indicates that in case of utilizing PMD as a sensor of hazardous gases we need to use the monochromatic light which wavelength corresponds to the inflection point of the long-wave absorption edge of PMD. Such sensor of hazardous gases can detect changes in the optical density of the sensor layer or the light intensity transmitted through the layer.

Purpose: The purpose of this study was to model the influence of cataract on Spectral Domain Optical Coherence Tomography (SDOCT) image quality and Retinal Nerve Fibre Layer (RNFL) thickness measurements. Methods: SDOCT images, made with two different devices (3DOCT-1000, Topcon and Cirrus HD-OCT), before and after cataract surgery were compared and judged against measurements from normal subjects using artificial filters simulating the effects of cataract. Optical density of the images was calculated based on a mathematical model described previously. Results: In total, forty-eight eyes were included for pre- and postoperative cataract extraction measurements. OCT image quality significantly (p

This paper explores the potential of optical coherence microscopy (OCM) for the in situ monitoring of biofilm growth. The quantitative imaging of the early developmental biology of a representative biofilm, Klebsiella pneumonia (KP-1), was performed using a swept source-based Fourier domain OCM system. The growth dynamics of the KP-1 biofilms and their transient response under perturbation was investigated using the enface visualization of microcolonies and their spatial localization. Furthermore, the optical density (OD) and planar density of the biofilms are calculated using an OCM technique and compared with OD and colony forming units measured using standard procedures via the sampling of the flow-cell effluent. MOE (Min. of Education, S’pore) EDB (Economic Devt. Board, S’pore) Published version

The radiochromic film, which is used, in combination with a flatbed scanner has become a widely used tool for a quantitative evaluation of radiation dose in radiation therapy. One aspect of uncertainty using the radiochromic film is the magnitude of orientation effects when the orientation of the film is not kept constant during the digitization process. The aim of this note was to investigate the impact of using a combination of two crossed sheets of EBT2 film on various aspects of radiochromic film dosimetry. First the impact on the film sensitivity was studied. We also investigated the influence on orientation effects during scanning. The results show that the double crossed film combination increases the sensitivity with a factor 1.7-2.1 and practically eliminates the effects of film orientation on the optical density read-out and the lateral correction profiles.

Offset paper properties have great influence on the quality of print matter. Eleven offset paper samples were printed by IGT printability tester, then the density and L*a*b values of printed samples were measured. The relationship between paper properties and optical density or color gamut of paper printed was studied. The results show that main density increases with the increased ink quantity before the main density reaches saturation, the saturation density becomes greater with increased ink absorbency. When the smoothness is larger, lower ink quantity is needed for reaching saturation density, and larger color gamut is obtained. This study will provide references for the paper making and printing enterprises.

EBT2 film is widely used for quality assurance in radiation therapy. The purpose of this study was to investigate the homogeneity of EBT2 film among various lots, and the dose dependence of heterogeneity. EBT2 film was positioned in the center of a flatbed scanner and scanned in transmission mode at 75 dpi. Homogeneity was investigated by evaluating gray value and net optical density (netOD) with the red color channel. The dose dependence of heterogeneity in a single sheet from five lots was investigated at 0.5, 2, and 3 Gy. Maximum coefficient of variation as evaluated by netOD in a single film was 3.0% in one lot, but no higher than 0.5% in other lots. Dose dependence of heterogeneity was observed on evaluation by gray value but not on evaluation by netOD. These results suggest that EBT2 should be examined in each lot number before clinical use, and that the dose calibration curve should be constructed using netOD. PACS number: 87

In this work laser interference technique was used to detect haematological disorders such as anaemia ,thrombocoytopenia ,leucocytosis this technique is called the laser sheet interference technique developed by professor Hatem El Ghandoor for measuring the optical density of blood components , the obtained results applying by this technique proved that The laser interference technique could be used as a very sensitive tool for measuring haemoglobin of blood and It may be considered as the basis for designing a new prototype to measure haemoglobin based on a laser interference

The research finds out some existing certain regularity, and further revises the formula D=D∞(1-e-ml). The formula means the relationship between ink thickness and ink in density. By using the formal of one-color ink thickness and ink density, the second density that correspond the first major density is transferred to the equal thickness. Then they are added together. According to the formula the real ink density is calculate. Then use the above formula to work out ink thickness. In this way, overprint densities come out, and make contrast with the actual measure data, so the new model formula is built up. The result shows that the average error between the overprint density calculated by ink thickness and the actual measure data is about 0.07. However, the average error between the calculated density using the simple adding method and the actual measure data is about 0.5, so this method is practical and more accurate.