According to research, sanitation devices that emit high doses of germicidal UVC are an efficient means of killing fungi, viruses, bacteria and protozoa – single-celled organisms. They have been successfully used in treating water, air, sewage, for food safety, medical settings, public transport and more.

collimation-1 The process of bringing the optical elements of an optical system into proper relationship with each other. The process of bringing the collimated system into proper relationship with the pointing mechanism is called alinement. 2 Adjusting the fiducial marks in a camera so that the lines through them intersect at the principal point.

The last two can pass the ozone layer in our atmosphere, while the first three are blocked – good news for life on Earth, since UVC in particular can be harmful to living things.

Matthew Olsen and Rashed Alghafri do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

collimation, line of—The line through the second nodal point of the objective (object glass) of a telescope and the center of the reticle; line of sight, sight line, pointing line, aiming line of the instrument. The center of the reticle is defined by the intersection of cross-hairs or by the middle point of a fixed vertical wire or of a micrometer wire in its mean position. In a leveling instrument, the center of the reticle may be the middle point of a fixed horizontal wire.

collimation adjustment—The process of bringing the line of collimation of a telescope into close agreement with the collimation axis. Also called “adjustment for collimation.”

What is collimationin x ray

Ultraviolet light is light with wavelengths just short enough that most humans can’t see it under normal conditions. The most ubiquitous source of UV is the Sun, which radiates everything from vacuum UV to far UVC, UVC, UVB and UVA rays (see below).

Read more: Ultraviolet radiation is a strong disinfectant. It may be what our schools, hospitals and airports need

However, the market is unregulated, with serious concerns about the quality and safety of some dubious devices available for consumers. In 2020, the lighting industry body Global Lighting Association raised its concerns:

What is collimationof a telescope

collimator, vertical—A telescope so mounted that its collimation axis can be made to coincide with the vertical (or direction of the plumb line). The vertical collimator serves as an optical plumb line; it may be designed for use in placing a mark on the ground directly under an instrument on a high tower or in centering an instrument on a high tower directly over a mark on the ground. See also collimator, auto.

One example is the booming industry of devices that use ultraviolet radiation (UV) to kill germs. While UV can successfully sanitise the air, or objects such as your smartphone, it can also come with cancer risk if the radiation is not behind a proper barrier.

collimation plane—The plane described by the collimation axis of the telescope of a transit or theodolite when rotated around its horizontal axis.

At a wavelength of 250–260 nanometres, energy generated by UVC rays can penetrate through microbes to break their DNA and RNA, disrupting their cell functions and killing them.

What is collimationin surveying

collimate-1 In physics and astronomy, to render parallel to a certain line or direction; to render parallel, as rays of light; to adjust the line of sight or lens axis of an optical instrument so that it is in its proper position relative to other parts of the instrument. 2 In photogrammetry, to adjust the fiducial marks of a camera so that they define the principal point; adjustment for collimation. See collimation; collimation adjustment.

The blue light you often see on such devices is either decorative, or the visible light emitted by the chemicals used to produce UVC – remember, the UV light itself is invisible.

Check the documentation. Is there evidence the device is effective against microorganisms? What’s the length of exposure, and how far from the source is the target being sanitised?

Collimating lens

collimation, error of—The angle between the line of collimation (line of sight) of a telescope and its collimation axis. When the collimation adjustment of an instrument is perfect (which is never the case), the line of collimation and the collimation axis coincide, and the error of collimation is zero. Usually, the adjustment is carried to where the error is so small that it can be considered to be negligible in many classes of work; or in precise work, after the adjustment is made, the residual error is either determined by observation and applied as a correction or is eliminated from the result by a suitable program of observations. Error of collimation is a systematic error and in a series of observations is usually treated as being of the constant-error type.

collimation axis—The line through the second nodal point of the objective (object glass) of the telescope and perpendicular to the axis of rotation of the telescope. In a surveyor\’s transit or theodolite, the collimation axis is perpendicular to the horizontal axis of the telescope. In a leveling instrument it is perpendicular to the vertical axis of the instrument. When the telescope of a transit is rotated about its horizontal axis, the collimation axis describes a plane called the “collimation plane.”

In the absence of a global regulatory body within the UVC market, the rule of thumb is to purchase only a fully sealed, enclosed UVC device operating with strict safety and efficiency to harm microbes, not you.

Recently, far UVC has been proposed as a possible solution to this challenge. Radiating at a wavelength of 207–222 nanometres, far UVC has a “shallow” skin entrance. However, the research with far UVC is very recent and so far mostly focused on animals.

Very few human studies have been performed, and some have been funded by companies prototyping far UVC devices, which can introduce a bias. Literature search reviews report different analytic parameters, which makes comparisons difficult to interpret.

Collimated beam

We will need trials with rigorous ethical approvals to investigate the full far UVC impact on humans. There is a lack of understanding how far UVC might affect people with thinner outer skin layers, affected by cuts, light sensitivity, or various medical conditions.

UV sanitation gadgets that operate without enclosure present serious health risks. Unfortunately, current lack of regulation means such devices are readily available for consumers to buy – and potentially be harmed by.

collimation error-1 Vertical—when the zero on the zenith circle is not aligned with the vertical axis of a theodolite. 2 Horizontal—when flopping the scope does not result in a 180° horizontal angle.

How to collimate a Dobsonian telescope

When it comes to buying a UVC gadget, buyer beware. Never buy anything that claims you can disinfect hands, the body, or a whole room while people are around. Skin cancers like basal cell carcinoma and squamous cell carcinoma are attributed to UV exposure.

To ensure the safety and efficacy of UVC devices available on the consumer market, we need watchdog bodies to urgently introduce rigorous global regulations.

UVC products without enclosure, such as the “disinfection wands” you might see on the internet, can be very unsafe. They can affect exposed skin, eyes and mucous membranes.

Collimationcap

“[I]n the midst of a global COVID-19 epidemic, GLA is concerned at the proliferation of UVC disinfecting devices – particularly being sold on the internet – with dubious safety features and inadequate safety instructions”.

Due to health risks, any non-enclosed UVC device should only be remote-controlled or automatic. It should also be equipped with safeguards, such as a sensor that turns it off if it detects anyone in the room.

The key is to have the UVC source fully enclosed and automatically stop if the device is open, so there’s no risk of exposing people to the radiation, which can cause severe burns and even increase the risk of cancer.

You also need to be aware that the cost of efficient and safe new technology and efficient UVC-producing LEDs is very high. Therefore, you may need to question the effectiveness of a relatively “cheap” device.

Hand hygiene was one of the earliest and most adopted measures to counteract the spread of disease, but there have been more technology-based approaches, too.

What is collimationin radiology

This is useful for germicidal (germ-killing) UVC radiation technology, although its efficacy depends on radiation intensity, the distance from light source to target, the type of surface being sanitised, and the wavelength at which the UVC is operating.

collimator, auto—A collimator provided with a method of illuminating its cross-hairs in such a manner that, when a reflecting image is placed normal to the emergent-light beam, the reflected image of the cross-hairs will appear to be coincident with the cross-hairs themselves. This device is used in the calibration of optical and mechanical instruments. The mark in a collimator can be viewed from very short distances as if it were at an infinite distance, and can therefore be used in place of a distant mark when making any adjustment of the line of sight (line of collimation) of an instrument. In adjusting a surveying instrument, the telescope of another surveying instrument can be used as a collimator, the reticle furnishing the mark; or the telescope of a discarded instrument can be placed on a special mounting to form a permanent installation. In some astronomical instruments, a vessel of mercury, placed directly under the instrument, is used as a collimator. A prismatic eyepiece used with such an instrument is sometimes called “collimating eyepiece.” A collimator of special design may also be constructed for a particular purpose. See also collimator vertical.

collimator—A device consisting of a convergent achromatic lens with a mark placed in the plane of its principal focus so that rays from the mark through the lens emerge along parallel lines.