Illuminance Meters

Compact, light-weight and easy to use multifunctional illuminance Meter

The latest generation of Konica Minolta lux meters, the T-10, replaces the globally successful models of the T-1 series. The small, easy-to-use handheld meters are capable of measuring intermittent light sources, can be connected to each other to form multi-point units and are easily controlled with a PC. They have an extremely large measuring range of 0.01 to 299,000 lx with automatic range switching and a large, backlit LCD. All this with Konica Minolta's renowned high level of precision in a small, compact design.

Areas of application

Konica Minolta lux meters are used whenever brightness and the quantity of ambient light must be measured. Even the measurement of average values and illumination is possible. Examples of their use include the measurement of workplace and street illumination, the production of lamps as well as architectural, forestry, and agricultural applications. Deployment in hard-to-reach spaces and under water are possible, just as the metering of very large surfaces and projectors (ANSI lumens) by serial connection of several receptor heads. Metered values can also be visualized graphically and even fully automated by using the PC software.

Background knowledge

As the names implies, lux meters measure lux (lx). That is the unit of illumination strength E, the light striking a certain location or the lumens (F) illuminating a certain surface (A):
E=Φ/A

In nature, luminance ranges from about 0.01 lx on a dark night of a new moon to about 100,000 lx on a hot summer day. Workplace illumination is normally around 1000 lx, many standards specify minimum values for the workplace. In some countries, the unit foot candles (fcd) is also used to denote illuminance. Of course, the T-10 will also display these values when desired. 1 fcd = 1 lm/ft² = 10.764 lx

The T-10 series of lux meters can also monitor the integrated illuminance for up to 9999 hours and then determine the exposure H in lux hours (lxh). That is the measurement for the amount of light that falls onto a certain surface within a certain time (t), for example how much light a plant receives throughout a day:
H = E · t
With the ability to connect up to 30 receptor heads in series, the T-10 series can be built into a system for the measurement of ANSI lumens of projectors. The unit lumen (lm) designates the light energy (F) emitted by the projector. It is measured indirectly over light striking a certain surface using 9 receptor heads.

Basic model T-10

The general purpose unit for most applications. It is based on the same base unit common to all models of the T-10 series with operating panel, analysis unit and display and a removable standard receptor head. This modular concept allows the combination of various receptor heads and the expansion of the unit for adaptation to your measurement tasks.

The most important features at a glance

All models of the T-10 series allow a variety of possibilities for measurement and analysis that leave nothing to be desired. The most important operational functions are accessed using three large buttons. An additional operating panel for less commonly used features is found under a sliding cover. That way, you are not distracted by additional operating elements during everyday work. A large, backlit liquid crystal display shows the measurement values; the illumination is automatically switched on as soon as it gets too dark. The T-10 models offer the following possibilities for analysis:

• Absolute measurement of illuminance in lux and foot candles.
• Comparison of illuminance values as a difference or percentage value. The target level can be entered by measurement or manual entry with the keypad.
• Integrated illuminance (exposure) with a display of the integration time and the illuminance mean value.
• Other evaluation options with the software T-A30

Other features facilitate daily use of the T-10 even more:

• Automatic, rapid zero calibration (without cap!) after switching on.
• Measurement of continuous and intermittent light sources.
• Very large measurement range of 0.01 to 299,900 lx with automatic range switching. Range switching can also be done manually.
• Entry of colour correction factors for adaptation to certain light sources.
• Serial connection of up to 30 receptor heads for multi-point metering.
• Digital (RS-232C) and analogue output ports for external use of the measurement values.
• Extensive accessories.

Serial connection

One of the special characteristics of the T-10 series is the ability to connect multiple receptor heads through a serial port. This allows measurements to be taken at several points simultaneously without having to move the instrument. That way, large areas such as movie screens, can be measured easily. With the help of the T-A30 Software you can measure the ANSI lumens of projectors for example.
Up to 30 receptor heads can be connected at once and the measurement values can be called up with the base unit. The individual receptor heads are connected with a common LAN cable (10BASE-T) that can be up to 100 metres long. The various receptor heads are separated from each other and from the evaluation unit.
Multi-point measuring becomes very easy with the T-A30 software. The software also graphically displays the system and allows the simultaneous display of all measurement values.

Accuracy

Spectral luminous efficiency V(l) defines the human eye and instruments should match this spectral response. The chart shows the T-10?s remarkable alignment to this standard curve (f1 (CIE) within 8%). With discontinuous emitters, even higher accuracy can be achieved with the colour correction factor. The standard Konica Minolta calibration is performed to standard illuminant A.
The diffuser in front of the high-grade silicon photo diode is used for the accurate spatial evaluation of the light being measured. The ideal condition is cosine-shaped valuation over the wave angle; the deviation from this is a measure of accuracy. Also in such case the T-10 shows its strengths. The deviation becomes larger only at very high, nearly irrelevant wave angles.

Light wave angle Maximum cosine error
10° ± 1%
20° ± 1.5%
30° ± 2%
40° ± 3%
50° ± 4%
60° ± 5%
70° ± 8%
80° ± 20% 

Small sensor model T-10M

The instrument if space is tight. With a receptor head of only 16mm diameter (14 mm diameter measurement area) and a 1 metre long lead, you can measure even hard-to-reach and small spots. The receptor head of the T-10M can be combined into multi-measurement systems with the normal receptor head of the T-10. All other features are identical to the basic model T-10.

<Notes on the shape and size of the mini receptor>
The shape of the mini receptor head units (T-10M, T-10WL and T-10WS) was changed in May 2008; the size is approx. 1 mm higher than the existent units. When the mini receptor head unit is used in a measuring range of less than 50 cm, note that the displayed value may be different from that of the existent unit by several percent.