Illuminating objects


 

Vitrines

For many years fibre light has been the ultimate choice of lighting in museum vitrines. Due to the absence of IR and UV radiation, the photochemical decomposition and dehydration of the objects are the smallest possible. The large flexibility of fiber light is ideal in vitrines, where the light can be led from several angles, for instance if objects of various size should be thrown into relief in alternating exhibitions, or if shadows should be avoided.

 

 

Light level

In case of very light sensitive materials (paper, watercolours, coloured feathers and amber), the light level must not exceed 50 lux. More light resistant materials (for instance oil paintings, leather and wooden objects) can withstand 200 lux. These values apply to exposure for 40-45 hours a week, which are the usual visiting hours of museums. As a main rule it is important to have a light intensity somewhat above the required intensity, as this enables you to adjust the colour temperature to the required level. Reference is made to ROBLON LUX CALCULATOR which can be downloaded from Lux Calculator. Light quantity from 42 W generators is approximately 50% of that of 75 watt generators (Ø9).

 

 

Colour rendering

To obtain the best possible lighting result, the quality of the light must be as good as possible, meaning that the colour rendering index (CRI) must be bigger than 90. A CRI of 100 equals the light from a halogen lamp which contains all visible colours. The colour temperature of the light must be balanced against the actual light level (lux value).



At low light levels the colour sensitivity of the eye changes, the eye becomes more sensitive to blue. At 50 lux the colour temp. of the light should be 2500-2800 Kelvin, at 200 lux it should be approx. 3500 Kelvin.

 

 

Light generators

As a main rule, halogen lamps are recommended, partly because of the light colour (2.900 – 3.000 K), partly because of their fine colour reproduction (CRI equal to 100). Roblon’s 42 and 75 W light generators therefore cover most vitrine lighting projects. These two types are among the most quiet light generators on the market. As the light generator is often placed at the top or the bottom of the vitrine, it is essential that there is sufficient space around it so that it does not get overheated. Often it is necessary to make ventilation holes to increase the quantity of cooling air. Air intakes should be placed lower than the air outlets.

 

 

Fittings

With Roblon Lighting Division's selection of tiltable and adjustable fittings is it possible to build in fibre light in the most demanding places. See examples of typical vitrine fittings below:

 

Ball-and-socket joint

 fitting.

With optics.

Fixed fitting.
Without optics.

Tiltable fitting.

With optics.

Shelf fitting.

 

 


System design

It is important to design the light in a way that allows the objects to be lit correctly, that goes for quality as well as quantity. There must be sufficient light outlets to illuminate the entire object, the light colours must be satisfactory and the light level adequate.

 


Fiber types

Glass fiber is commonly used in vitrines, due to its influence on the colour temperature. The distance between light and objects is often small, so the “light distance law” is utilised. Cables for vitrine lighting are often short, so PMMA can be used to a large extent. For CRI > 90, cables must not exceed 5 metres.

 

 

Vitrines and shop showcases

As the light level is generally high in shops, PMMA fiber cables will most often be the first choice because of the higher light transmission ability. Also, the exhibited shop items are rarely as light sensitive as objects in museum vitrines, and they are exchanged more frequently. Apart from that, the same rules apply, and especially the correct placing of the light generator is important in order to avoid heat problems.

 

 

Vitrine and working light

Roblon Lighting Division's product range includes standard flex arms with PMMA-fiber cables Ø4.5 mm. Special solutions can be made regarding length, thickness and surface. Max. recommended length is 60-70 cm, as otherwise the flex arm becomes too heavy to carry itself.

 

Glass vitrine with built-in

tube system without fittings.

Glass vitrine with built-in

tube system with fittings.

 


 

 


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