by N Harnchaiwat · 2020 · Cited by 23 — In short, Hong-Ou-Mandel interference is the phenomenon where two photons that are incident on two orthogonal input ports of a beam splitter preferentially exit ...

Jul 10, 2015 — The focal length of a lens, expressed in millimeters, is the distance from the lens's optical center (or nodal point) to the image plane in the ...

Nov 9, 2023 — Parfocal means that multiple lenses or objectives in a system maintain focus when the magnification is changed. Parcentric means that multiple ...

What is a uv filterfor camera

2022126 — Focal length is a measure of the level of magnification (or field of view) of a lens and can be calculated with the formula below.

NTP is working to assess the safety of UV filters through a variety of studies in rodent and in vitro models. NTP conducted modified one-generation studies in rats to determine if 2-hydroxy-4-methoxybenzophenone (2H4MBP) and 2-ethylhexyl p-methoxycinnamate (EHMC), common UV filters, would adversely affect the animal’s ability to develop and reproduce. Previously NTP conducted a long-term study on 2-hydroxy-4-methoxybenzophenone (2H4MBP) to test the toxicity and carcinogenicity of chronic exposure to this chemical in rats and mice. NTP conducted endocrine disruptor panel screening studies to determine if EHMC and 2H4MBP (TR-597) activated the endocrine system. Six other chemicals are also being evaluated for endocrine activity in vitro.

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Q: What are toxicokinetic studies? A: A toxicokinetic study measures the concentration of the chemical in blood as a function of time. Toxicokinetic studies characterize how much of the chemical gets in and how long it stays in the body.

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This tutorial is intended to convey that measuring, or even rigorously defining, any single all-inclusive measure of laser beam quality is still a ...

Do I needa UV filterfor my lens

Final reports from two NTP Developmental and Reproductive Toxicity (DART) studies are now available (DART-05 and DART-06).

Some of the high index materials can have a reflectance value as high as 10-12%, and the AR coating will tame that down to well under 1%. Not ...

Q: What’s next for NTP on UV filter research? A: We are working on a report summarizing cell-based and short-term animal studies conducted on six additional UV filters: avobenzone, ensulizole, homosalate, octocrylene, octylsalicylate, and padimate-O.

Q: There are some who say that UV filters are an endocrine disrupting chemical. Did your studies find this to be true? A: In our cell-based studies, 2H4MBP at very high doses added to the culture media interacted with the estrogen and androgen receptors but did not result in the estrogen receptor or androgen mediated biological effects. EHMC did not interact with estrogen or androgen receptors or biological effects. Our studies on these two UV filters did not show endocrine disruption in animal models. In the larger MOG studies, 2H4MBP and EHMC did not induce effects consistent with estrogenic, androgenic, or anti-androgenic activity. Together these data suggest that in cell models at high concentrations, these UV filters can interact with receptors of the endocrine system, however effects were not observed in vivo.

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Q: How do NTP's studies on UV filters relate to humans? A: Results from the NTP MOG study reports on the toxicity of UV filters, 2H4MBP and EHMC, suggest that they do not show endocrine disruption in animal models. In the 2H4MBP MOG, NTP found uncertain evidence of reproductive toxicity in rats based on a decrease in F2 (offspring) litter size and evidence of developmental toxicity in rats based on postnatal growth retardation. In the EHMC MOG, NTP found no evidence of reproductive toxicity in rats. NTP found uncertain evidence of developmental toxicity in rats based on lower offspring weights, though they partially recovered by study end. When 2H4MBP was given to animals through repeated doses for two years, NTP found uncertain evidence of carcinogenic activity in one of the two rodent species tested. These findings do not suggest that UV filters will cause harm if used by humans in a typical application. It is also important to note that sun exposure without application of a sunscreen that blocks the UV rays can damage skin, and sustained exposure is associated with skin cancer in both animals and humans. The Centers for Disease Control and Prevention (CDC) offers tips to protect yourself from UV radiation.

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Q: What is the endocrine disruptor screening panel? A: The Endocrine Disruptor Screening Panel (EDSP) is a series of guideline tests that aim to determine if chemicals and environmental contaminants interact the estrogen, androgen, and thyroid hormone systems.

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Q: In your Modified One-Generation and two-year chronic toxicity and carcinogenicity studies, why did you give 2H4MBP to animals through food instead of applying it to skin? A: Our study aimed to mimic continuous exposure of 2H4MBP in the animals. Rodents eat throughout the day and thus had continual exposure, similar to applying and reapplying sunscreen to skin. This method models the amount of UV filters people could be exposed to via repeated application of sunscreens to the skin or by eating food that has touched UV filter-containing plastics.

See table below for the most up-to-date information on the variety of projects taking place at NTP. For general descriptions of the various studies, please see the FAQs.

Millions of people use sunscreen lotions, creams, and sprays on their skin to prevent sunburn and resulting skin damage. Specific chemicals, known as ultraviolet (UV) filters, are added to sunscreens to absorb or block UV radiation from the sun. UV filters are regularly used in cosmetics for sun protection purposes, and in other products like plastics, toys, or furniture finishes to limit UV degradation. People may be exposed to these chemicals when food comes into contact with plastics that contain UV filters. The UV filter and the body’s breakdown products of the UV filter have been found in urine, indicating that they make their way into the body.

Q: Who nominated 2H4MBP and EHMC; why? A: 2H4MBP and EHMC were nominated for study by the National Cancer Institute due to high prevalence of the chemical in commercial products such as sunscreens and cosmetics, and lack of carcinogenicity data.

Q: What is a modified one-generation study? A: The modified one-generation study, or MOG study, measures developmental and reproductive toxicity parameters, and enables the setting of appropriate dose levels for a cancer bioassay through evaluation of target organ toxicity based on chemical exposure that starts during gestation. This gives scientists the power to detect adverse effects where there is a prenatal exposure, but evaluations occur postnatally.

Q: What is an Absorption, Distribution, Metabolism, & Excretion (ADME) study? A: This type of study describes in more detail what happens to a chemical in the body in four different stages:

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