Fotometri: Me kadan da ake?
Photometry ita ce kimiyyar yadda mutanen jin dadin kai na tafiya. Yana da muhimmanci daga radiometry, wanda ke maimaito energy radiya (tare da dadin kai) a kan abubuwa mai zurfi. Photometry ba ta yi amfani da rayuwarsu da za su iya shiga mataki na mutum ba.
Mataki na mutum zai iya sanar da rayuwar da ya da zama da 370 nm zuwa 780 nm. Wannan rayuwar zai ake kira rayuwar da ake gano ko kuma dadin kai. Rayuwar da ya da zama da ɗaya da dadin kai zai ake kira rayuwar ultraviolet, kuma rayuwar da ya da zama da ɗaya da dadin kai zai ake kira rayuwar infrared. Photometry ba ta yi amfani da rayuwar ultraviolet ko infrared ba.
Photometry tana da asasinsu a kan hanyar tafiya na mataki na mutum a kan zama da wavelength. Mataki na mutum bai da matsayinta cikin rayuwar daban-daban. Yana da matsayinta daidai a kan dadin kai na green kuma yana da matsayinta ƙarin a kan dadin kai na red da violet. Mataki na mutum na iya haɓaka zuwa ƙarin level na tafiya. Yana da duɗɗukan tafiya: photopic vision da scotopic vision.
Photopic vision ita ce hanyar tafiya na mataki na mutum a kan ƙarin level na tafiya, kamar a lokacin da rana ko a kan lighting. Photopic vision zai iya kawo irin da kuma tafiyoyi. Scotopic vision ita ce hanyar tafiya na mataki na mutum a kan ƙarin level na tafiya, kamar a lokacin da ranar ko a kan starlight. Scotopic vision bai da kyau kawo irin ko kuma tafiyoyi. Akwai kuma masu haɗin da ake kira mesopic vision bayan photopic da scotopic vision.
Photometry tana amfani da models na standard na hanyar tafiya na mataki na mutum a kan ƙarin wavelengths da kuma level na tafiya. Models waɗansu suna kira luminosity functions. Suna amfani don kawo power na radiant a kan ƙarin wavelength da factor wanda yake kira yadda matakin mutum yana da matsayinta a kan wavelength. Luminosity function da ake amfani da shi daidai shine photopic sensitivity function, wanda ke model hanyar tafiya na mataki na mutum a kan photopic conditions. Wasu luminosity functions sun hada scotopic sensitivity function da mesopic sensitivity function.
Photometry tana da amfani da yawa a kan siffar nau'o'i, engineering, da kuma art. Ana amfani da shi don kawo da karkashin tafiya, irin, da kuma quality na light sources, materials, da kuma abubuwa. Ana amfani da shi don yanayin amfani na light a kan lalace, ƙwarewa, da kuma perception na mutum.
A cikin wannan takardun, zan yi bincike game da wasu types, principles, applications, da kuma working of photometry a cikin ƙarin bayani. Zan yi ƙarin talkarwa game da wasu instruments da units da ake amfani da su don measurements na photometric.
Meen Fiber Photometry?
Fiber photometry ita ce hukuma da ake amfani a kan neuroscience don record activity na neurons a kan animals da suke. Ana amfani da optical fibers don deliver excitation light zuwa neurons wadanda suka express fluorescent indicators da kuma collect emitted fluorescence daga su.
Fluorescent indicators suna da molecules wadanda suke canza properties na fluorescence su saboda canzawa a kan biological parameters, kamar calcium concentration, voltage, neurotransmitters, etc. A nan amfani da genetically encoded fluorescent indicators (GEFIs), kamar GCaMPs, ana iya target specific types of neurons ko brain regions don optical recording.
Fiber photometry tana ba da shirye-shiryen activity na large populations of neurons over time. Ana iya amfani da shi don correlate activity na neural da events ko stimuli a kan animals da suke. Fiber photometry tana da advantages daga wasu optical recording techniques, kamar two-photon microscopy ko calcium imaging, a kan simplicity, cost-effectiveness, portability, da scalability.
Amma, fiber photometry tana da wasu limitations, kamar low spatial resolution, signal contamination from background fluorescence ko movement artifacts, da kuma potential tissue damage ko inflammation from fiber implantation.
Meen Flame Photometry?
Flame photometry ita ce hukuma da ake amfani don chemical analysis don determine concentration of certain metal ions a kan sample. Ana kiran shi kamar flame emission spectroscopy ko flame atomic emission spectroscopy.
Flame photometry tana da asasinsu a kan hanyar da some metal ions ke emit characteristic wavelengths of light idan an yi heat in a flame. Intensity of the emitted light is proportional to the concentration of the metal ions in the sample.
Flame photometry tana da amfani da alkali metals (group 1) da alkaline earth metals (group 2), kamar sodium, potassium, calcium, lithium, etc. Waɗannan metals suna da low ionization energies da suke iya excited by thermal energy from a flame.
Don perform flame photometry, sample solution containing the metal ions zai a spray into a flame (usually an air-acetylene flame). The flame vaporizes and atomizes the sample into its constituent elements. Some of these atoms are then excited to higher energy levels by absorbing thermal energy from the flame. These excited atoms eventually return to their ground state by emitting photons of light with specific wavelengths corresponding to their energy transitions.
The emitted light is then collected by a lens system and passed through a monochromator (a device that selects a narrow range of wavelengths). The monochromator allows only the desired wavelength of light corresponding to the metal ion of interest to reach a detector (usually a photomultiplier tube or a photodiode). The detector converts the light signal into an electrical signal that can be measured by a meter or a recorder.
The concentration of the metal ion in the sample can be calculated by comparing the intensity of the emitted light with a standard curve obtained from known concentrations of the same metal ion.
Meen Reflectance Photometry?
Reflectance photometry ita ce hukuma da ake amfani don kawo color ko reflectance properties of a surface or an object. It works on the principle that different surfaces reflect different amounts and wavelengths of light depending on their physical and chemical characteristics.
Reflectance photometry uses a light source (usually white light) to illuminate a surface or an object at a certain angle. The reflected light from the surface or object is then measured by a detector (usually a spectrophotometer or a colorimeter) at another angle.
The detector analyzes the spectrum or intensity of the reflected light at different wavelengths and compares it with a reference standard (usually a white surface). The color or reflectance properties of the surface or object can be expressed by various parameters, such as hue (dominant wavelength), saturation (purity), brightness (luminance), chromaticity coordinates (x,y,z), color index (CIE Lab*), etc.
Reflectance photometry can be used for various purposes, such as quality control, color matching, color identification, color communication, etc. It can be applied to various materials and objects, such as paints, textiles, plastics, metals, and ceramics.
Meen Photometric Quantities and Units?
Photometric quantities are derived from radiometric quantities by applying the luminosity function as a weighting factor. The luminosity function represents the relative response of the human eye to different wavelengths of light. The most commonly used luminosity function is the photopic sensitivity function, which models the eye’s response under bright conditions. Other luminosity functions include the scotopic sensitivity function, which models the eye’s response under dark conditions, and the mesopic sensitivity function, which models the eye’s response under intermediate conditions.
Meen Photometric Instruments and Methods?
Photometric instruments are devices that measure photometric quantities using various methods and principles. Some of the common photometric instruments and methods are:
Photometers: Photometers are devices that measure the relative brightness of light sources or objects by comparing them with a reference standard. Photometers can be classified into different types based on their design and application, such as visual photometers, photoelectric photometers, filter photometers, spectrophotometers, etc.
Colorimeters: Colorimeters are devices that measure the color of light sources or objects by analyzing their spectral composition. Colorimeters can be classified into different types based on their design and application, such as tristimulus colorimeters, chromameters, spectroradiometers, etc.
Integrating spheres: Integrating spheres are devices that measure the total luminous flux of light sources or objects by enclosing them in a spherical cavity with a highly reflective inner surface. Integrating spheres can be used for various purposes, such as calibration of light sources, measurement of reflectance or transmittance of materials, measurement of the angular distribution of light sources, etc.
Goniophotometers: Goniophotometers are devices that measure the angular distribution of luminous intensity or luminance of light sources or objects by rotating them around one or more axes. Goniophotometers can be used for various purposes, such as the characterization of light sources, measurement of optical properties of materials, measurement of glare or contrast ratios of displays, etc.
Photodetectors: Photodetectors are devices that convert light into electrical signals by using various physical principles, such as the photoelectric effect, photovoltaic effect, photoconductive effect, etc. Photodetectors can be classified into different types based on their design and application, such as photodiodes,
