Opacity is the name given to the characteristic of opaque. The term, which derives from the Latin language (opaque), is linked to the ownership of the materials that block much of the light.
The opacity, therefore, depends on the degree of light going through a material. When the light is largely blocked, the material is said to be opaque. If the flow of light that passes is large enough, the material will be classified as translucent. And if the light passes through the material in its entirety, we are facing a material transparent.
Within medicine, the term at hand is also used. Specifically, in this field of health we talk about what is known as corneal opacity. This is a problem that, as its name suggests, affects what the cornea of the eye is.
More precisely, we can say that it is a corneal disorder that occurs due to an infection, an inflammation in the eye, a dystrophy, a degeneration or an injury. What it basically translates into is that the person suffering from it sees their field of vision significantly diminished and even, depending on the severity of the case, they can perceive highly distorted images.
In those cases, the treatment that is applied to people who have this problem is none other than a corneal transplant. But this is in the most serious cases. When it is still a mild or superficial disorder, it will be sufficient to carry out what is known as phototherapeutic keratectomy.
The colloquial language notices the opacity of an object according to how it interrupts the advance of light that enters the visible spectrum. For example: if a man is sitting in front of a computer monitor in an office and is bothered by the sun’s rays when working because of the reflection they generate, he will want to use a curtain to block the light. Said curtain, therefore, will have to be opaque to fulfill the objective. The opacity will be confirmed by the person in question when you discover that the sun is no longer a nuisance.
On a more technical level, opacity is not measured according to the light that can be seen with the naked eye, but rather uses various instruments that can analyze the passage of the electromagnetic waves, from ultraviolet or infrared radiation, etc. In this sense, opacity also appears associated with various environmental conditions and the temperature of the material, among other characteristics of the physical.
In the case of the automotive industry, we also speak of opacity. In your case, it must be said that when any car is passing the ITV (Technical Vehicle Inspection) it also undergoes the well-known diesel smoke opacity test. With this, what is tried is to verify that the fumes emitted by the car with a diesel engine conform to the legally established parameters, in favor of the protection of human health and the environment.