In a broad sense, light is any visible optical radiation. In the branch of physics that studies optics, light is considered as an electromagnetic wave (light flux) with a certain range of wavelengths or, in other words, a stream of photons with some own energy. In order to measure the power of the light flux, you will have to collect all the light emanating from a particular source, and take into account all its rays diverging in all directions. It is not easy to do this, complex and expensive devices are used for this purpose. Measures the characteristics of the luminous flux in lumens.
Luxmeter is…
It is much easier to measure the illumination - one of the characteristics of the light environment. The unit of illumination from a luminous flux falling on a surface is lux (translated from Greek - "light"), which is derived from the formula for the ratio of the luminous flux to the surface area on which it falls. A light meter is a device whose purpose is to control illumination. Units of measurement are indicated as lx.
When people talk about illumination, they don't mean any particular source of light (a light bulb or a flame of fire), but its environment. Around the light source are furnishings that reflect light. There is some distance between them, lighting devices have different light intensities. The design of the light meter takes this into account. You can work with it both outdoors and indoors.
Digital
Digital light meter, which replaced the switch, is used to check compliance with working conditions at workplaces. Illumination affects the processes occurring in the human brain. Both weak and excessively bright light act unfavorably, therefore, concentration of attention may decrease, efficiency may decrease, and drowsiness will prevent one from concentrating on the performance of production tasks. All this in general increases the risk of injury and the number of accidents. Timely measurements with a luxmeter of illumination in production workshops, at construction sites, at the sites of enterprises associated with hazardous production and difficult working conditions, will prevent unpleasant incidents, and even deaths.
Device with luminance meter
In order to be able to control the environment in which the employees associated with working displays and computer monitors are located, a light meter and a brightness meter were connected under the cover of one device. It is very comfortable. Measurement in the visible region of the spectrum of illumination parameters is a task for a luxmeter. This isis complemented by the simultaneous control of the brightness emanating from the device. It is used when examining the working space in educational and scientific institutions, in archives, in schools when arranging computer classes, libraries, transport enterprises, museums, factories and various laboratories. This device is needed in farming and medicine.
When growing various vegetable crops in greenhouse and greenhouse conditions, the development of fruits of which depends on the length of daylight hours and lighting conditions, some modifications of luxmeters are indispensable meters of light fluxes and other indicators. The TKA-PKM luxmeter used for technical control and supervision is in special demand in IT companies, metrological and certification centers. The device, in addition to its direct purpose, can measure the relative humidity of the air and its temperature, the speed of air movement, the flow rate through the ventilation channels of the air flow. You can use the device non-stop for eight hours, the power source is a rechargeable battery. The device weighs 0.5 kg.
Working with the device
They start working with the luminance meter after the display indicates the end of the countdown from the moment the device is turned on, that is, from the moment it is ready for operation. Using the measurement menu, the parameter required for control is selected. Having carefully studied the instructions, we can say that the light meter is a rather complicated device in terms of a constructive solution. Butwhile it is easy to operate. Therefore, you can easily get and fix the necessary values.
Dial gauges
The forerunners of modern digital light meters were pointer meters. But the design of any of these devices is based on a semiconductor device - a photocell or a photodetector. In the very first bulky analog luxmeters, measurements were demonstrated and calculated by controlling the deflection of the pointer in the galvanometer. They are noticeably different from modern portable digital instruments with non-breakable housings, in which the results of measurements of sensitive elements are displayed on a liquid crystal screen. In advanced models, the measuring module is connected by a cable to the display unit. Thanks to this, you can conduct an examination in any, even inconvenient place. In cheaper devices, the photocell block is mounted directly into the body of the light meter.
Heart rate monitor
The operation of the luxmeter-pulsemeter is based on fixing changes in the transparency of human tissues during cardiac activity. This device is produced in various modifications, it can be worn as a clip on the ear or as a clothespin on the finger or wing of the nose. The device, using a peripheral sensor and a microprocessor, displays the received heart rate indicators, measured as the number of heart beats per minute. The sensor is equipped with LEDs.
Human blood and soft tissue transmit light fromemitter, which is either a laser or an LED. Light absorption depends on how oxygenated the blood is. The detector fixes the change in the transparency of tissues and capillaries. Transparency depends on the level of oxygen, and fluctuations in transparency make it possible to measure the heart rate. To obtain reliable pulse values, complete immobility of the organ on which the heart rate monitor is put on is required.
Photoplethysmograph
There is a device with a difficult-to-pronounce name photoplethysmograph that controls the pulse wave with the transfer of measurement results to a device that operates on the principle of a smartphone. For measurements, the already mentioned points on the phalanx of the finger and earlobe, as well as the wrist and temple are used. To obtain a photoplethysmogram, a photodetector and an LED serving as a light source are used. There are two ways to position the source and destination. The first method is "on reflection", it involves light hitting the skin and, after reflection, returning to the receiver. In the second case - "through" - the radiation source and the receiving device are on opposite sides of the measurement point. The beam is not reflected, but passes through the body.
Device with a heart rate monitor. Features
Luxmeter-pulsemeter is a device not only for monitoring the state of the cardiovascular system of hospital patients, but also for he althy people who are passionate about sports or recreational activities. For the latter, it is important to control cardiac loads so as not toprevent painful attacks and stop training. Taking into account the readings of the heart rate monitor, training programs and loads are developed. The device is indispensable because it is easy to use, small in volume (it has a case with a strap), and should always be in any sports bag.
For people suffering from hypertension or other abnormalities in the work of the heart muscle, the pulse meter, as one of the varieties of the luxmeter, becomes a lifesaver when there is a need for long-term monitoring of the state of the blood and pulse rate. Importantly, there is no need for arterial blood sampling. The easy-to-use instrument is made easy by the clear instructions that come with it, and the ergonomic design features make it durable and impact-resistant.
