The Basics of Measuring Visible Light – A Primer on Photometry Tools


The Basics of Measuring Visible Light – A Primer on Photometry Tools

Radiometric Description

Radiometry is a broad field encompassing all techniques for measuring electromagnetic radiation, including the measure of visible light. These techniques measure the distribution of the radiation’s power in space. This field includes photometry, which more specifically measures attributes of electromagnetic energy that are visible to the human eye. Instruments in this category address both the broad and more specific attributes of light these fields cover.

LED Analyzer

LED Analyzers measure the luminous flux of LED lights. This means that the unit measures the total visible energy emitted by a light source. Typically, these incorporate a sphere in which the light source to be measured is placed; the sphere focuses all the power emitted from the light source directly on the detection component. Gigahertz-Optik offers analyzers with a range of different sphere sizes to meet any need.

Light -1Light Meters / Illuminance Meters

An Illuminance Meter measures how much a given incident light illuminates a surface, unlike a luminance meter, which measures the light being emitted from a particular area. Many illuminance meters do also function as luminance meters given they use certain attachments.

Illuminance is basically another word for brightness. However the term brightness should not be used for quantitative description. Therefore we say illuminance. Today illuminance meters can effectively measure most types of visible light.

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Key Features of Light Meters / Illuminance Meters

  • Measuring Modes. Some meters can measure Illuminance, illuminance difference, average illuminance, illuminance ratio, integrated illuminance, and integration time. Most other meters can measure in a maximum of five modes and many often require special attachments to measure in certain modes.
  • Accuracy Classification. Meters are classified by DIN and JIS standards.
    • DIN classes: L, A, B, C
    • JIN classes: Precision, AA, A, B

Class L and Precision are the highest classes in each, respectively. A higher class translates to greater accuracy. However, it will also mean a higher price.

  • Illuminance Range. Most meters typically have a maximum range of 199,900 lx

Luminance Meters

Luminance is a photometric measurement of the luminous intensity of light travelling in a given direction. In other words, it describes the amount of light that passes through or is emitted from a particular area at a particular solid angle. This type of measurement is especially useful because it quantifies the properties of light that the human eye actually perceives. Measuring these quantities of light is essential, for example, for TV studios, sports arenas, emergency situation lighting, traffic lighting, and automobile lighting.
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Light - 4Key Features of Luminance Meters

  • Measuring Method. Luminance meters can measure either with contact or from a distance. Many can perform both, but some can only do one or the other, so choose wisely based on your needs.
  • Measuring Modes. Luminance meters can measure several attributes of luminance. Typically units can measure luminance, luminance ratio, and peak luminance/luminance ratio. However, some units can measure more than just these attributes.
  • Luminance Range. This is simply the range of values a luminance meter can measure. This range differs depending on measuring angle.

Established in 2004, NorthTree Associates (Cologne, MN) is a North American distributor that provides unique electronic test & measurement tools for design engineers, test engineers and production engineers.


NorthTree Associates Announces Micsig Sales Promotion On TO202 and TO202A tBook Tablet Oscilloscopes


A new Micsig sales promotion is underway at NorthTree Associates. The Micsig TO202 and TO202A  tBook Tablet Oscilloscope have been put on sale at special prices.

The Micsig TO 202 tBook Tablet Oscilloscope has 2 channels, a 200MHz bandwidth, and a 1GSs sampling rate is now priced at $669.00. CLICK HERE NOW to order and see complete specifications.

In addition, the MicsigTO202A tBook Tablet Oscilloscope has 2 channels, 200MHz bandwidth, and a 2GSs sampling rate is now priced at $769.00. CLICK HERE NOW to order and see complete specifications.

As the tBook Tablet Oscilloscope innovator, Micsig has achieved various worldwide patent rights, software copyright for their touch screen tBook Tablet Oscilloscope. Features include: a multi-touch screen, 100MHz to 200MHz bandwidth, 2 or 4 channels, real time sampling rates of 1GS/s to 2GS/s, compact design, high memory depths, and excellent function features.

The affordably priced Micsig handheld oscilloscopes offer bandwidths ranging from 70MHz up to 200MHz, two channels and 1GS/s sampling rate, making them deal for both laboratory testing and field service applications across a wide range of industry sectors.

High performance features offered by Micsig oscilloscopes include isolated inputs for safely carrying out floating measurements, up to 190,000 wfms/s refresh rate, support for serial bus protocol trigger and decode (1553B/429/UART/232/485/LIN/CAN/SPI/12C) in both graphic and text modes, and multi-function operation including digital oscilloscope, digital multimeter and recorder.

In oscilloscope mode, the units offer a wide range of trigger types, 31 automatic measurements, and maths functions including FFT. Isolated input versions offer up to 1000V CAT II 600V CAT III maximum channel floating voltage.

Designed for user-friendly operation with Micsig’s touch screen technology, the oscilloscope offers three operation modes – moving the waveform, zooming in and out, and menu option selection – with the large 5.7 inch TFT LCD screen providing users with a sharp 640 x 480 high resolution display. A user selectable indoor (black background) or outdoor (white background) display mode makes the models particularly useful in field service applications.

The Li-ion batteries provide users with up to 6 hours of continuous operation, while the USB host and slave interface allows users to easily download captured waveforms as well as connect the oscilloscopes to a PC.

NorthTree Associates based in Cologne, MN provides unique Electronic Test & Measurement tools for increasing productivity. You can reach NorthTree Associates at

Multimeter: The Swiss Knife of Electronic Test & Measurement Tools

Main View

Recently, there has been a move towards increasing the functionality of many Electronic Test & Measurement tools that engineers use. The supposition is if one tool can do multiple tasks, engineers will need fewer tools, which can mean fewer tools on the workbench and fewer tools to calibrate. However, it has been indicated additional functions may limit the effectiveness of a tool to complete its primary task and any secondary features may not perform as well as a single-purpose product.

A multimeter is a multipurpose tester that has been a commonly used test tool that has been around a long time. Although analog multimeters are still being used, most multimeters now are digital. For engineers, it is a must have portable tool.

The latest DMM models have increased capabilities along with wireless functionality, and virtually limitless options. A single multimeter can meet varying needs.
Engineers may be more interested in fast go/no-go (noncontact) testing for voltage presence, and low-impedance modes for preventing false readings caused by ghost voltage.

Instead of searching for a digital multimeter that has 20 or 30 dial positions to cover every possible measurement, engineers should look for a DMM with measurement capabilities that fit their most common tasks. Wireless communications is a common feature of digital multimeters. These units take a single, momentary measurement and stores it in a database. Having the capability to store readings can prove helpful when conducting a series of readings that need to be logged. Taking it a step further, advanced DMMs offer Bluetooth capabilities to stream readings to a mobile device which would display readings remotely. Using a smartphone or tablet for remote viewing can help improve safety and also make it easier to operate equipment not immediately adjacent to the point of measurement.

Current multimeters are more versatile beyond the scope of standard multiple measurement modes. For example, a low-pass filter can ensure precision readings even when signals are noisy. It would be useful for working on variable frequency drives [VFDs]. Low Z mode does not allow so-called ‘ghost voltage’ to affect readings. Point-and-shoot infrared surface temperature measurement is a popular option on multimeters.

Also, richer, higher quality color displays has increased the usability of multimeters. High-contrast, dot-matrix LCDs are easier to read and brings the multimeter display beyond numerical values and labels and to a more advanced graphical reading displays for better testing results. A side benefit of being able to incorporate mobile capabilities is connectivity with other tools like infrared cameras. A multimeter can transmit electrical readings to an infrared camera, which can imprint those readings on related thermal images for effective testing and documentation.

There are now two distinct types of multimeters: units with high display count and accuracy for electronics engineers and units with high CAT safety ratings (IEC 61010) with acceptable functions for the electrical engineer or field engineer. If portable durability is needed, a user should check to see durability specifications.

Established in 2004, NorthTree Associates (Cologne, MN) is a North American distributor that provides unique Electronic Test & Measurement tools for design engineers, test engineers and production engineers.wireless