Archive for the ‘Uncategorized’ Category

After reviewing a range of different metering choices in actual use, I compiled a summary of findings, as well as my own personal subjective ratings of features and overall utility as a lighting professional. This chart is the collection of all findings in a simple comparison table for those who find this useful (like me):

The Meter Comparison Table in .pdf format.

Note that all of the meters tested were shown to deliver accurate results when testing LED products, as well as conventional lamps. This is not always the case. Many older meters do poorly under LED light sources, either delivering unreliable results, or unstable readings. One example of this are the obsolete Minolta meters manufacturer before LEDs had entered the market. These often deliver CCT results that are far enough off more current meters as to render them essentially useless. Also, some LED products flicker at a frequency that creates moving readings, which never stabilize enough to be readable. The meters I have that exhibit this behavior were excluded from review completely, for obvious reasons.

This is by no means a comprehensive review of all the meters available to designers and engineers. I could have scoured web sites and pulled down more data to include objectively from indirect information. However, that was not my intention, and like the results I get from testing actual products against published data, there is no substitute for directly using and testing any product. The problem for most of us is that testing every option before buying is just not possible, or practical. So, with that in mind, and reflecting the fact that I have both collected more than my share of instruments and put them to use, and have had access to others purchased for and with customers, I offer the reviews as they stand. In this, simply regurgitating what I get from web sites would only pollute the results, as anyone can do that, as that is how I came to purchase those products I have, for both good and bad results. I hope that this this is of value to those making your own decisions, hoping to avoid some of the redundant purchasing decisions I have, that has led to having this many meters collected to review.

That all said, if anyone has a meter they feel was unfairly excluded here, that would like to be added, I offer this. Send me the meter and give me a few weeks time to play with it, and put it to use in tests we are completing on a regular basis. This includes whatever software is required to create a complete picture of the product in actual use. I’ll add what I find to the meter reviews by adding an entry for the specific product, and update the summary comparison table before returning the meter – unless I find I can’t live without it and find myself compelled to add to my collection – which we can discuss at the time.

This is the Lighting Passport Flagship set. Includes case and accessories in a neat package.

This is the Lighting Passport Flagship set. Includes case and accessories in a neat package.

I first saw this device at Light+Build Frankfurt last fall. I was impressed enough to find one added to my collection of tools. The Asensetek Lighting Passport is a unique product in several ways. First, it is essentially a meter head (where the cost is), coupled to an iOS or Android device that does all the computational and display work. The lighting head has a nifty slide action receptor cover, so there is nothing to come off or get lost in a bag or pocket. The measurement range is as broad as any of the other spectrometers tested here, plus some. Not only does it produce the expected spectral power distribution, CRI, CCT, CIE 1931 and 1976 coordinates and illumunance in lux and Fc, it also delivers CQS values. There are several additional data points worth singling out:

  • Du’v’ value. This is the missing piece of the CRI value we have always needed and were never provided. This tells you whether the light source is above or below the black body line. A positive value indicates the source will appear on the yellow/green side, while a negative indicates a tint of magenta will be present. When you put two sources side-by-side of the same CCT and CRI/CQS, you will see these differences clearly. Now, with the Du’v’ value, the difference will be quantified and usable in future comparisons when you don’t have both sources in the same room at the same time.
  • S/P (Scotopic/Photopic) value. This is the value that will drive future lighting decision making. This indicates how well a spectral power distribution satisfies both the scotopic and photopic visual response curves of the human eye, which combine to deliver mesopic vision, and is the center of most current thinking in explaining why we find one source more visually stimulating and clear over another. This is also the value described by the IES in TM-24 13, where the application of S/P ratios can be used to reduce energy use, by taking advantage of the dynamic advantage of high S/P ratio light sources ability to generate increased visual acuity at reduced illuminance levels.
  • PPFD, or Photosynthetic Photon Flux Density. This is the amount of light in umol/sec meter sq. in the spectral distribution (red and blue peaks over human vision in yellow green) that is used in lighting of plants. While not everyone will find this useful, when you need the data, this meter delivers it. Its also an interesting value when looking at how an artificial source and daylight compare, but that’s for another discussion.
  • FWHM color value. This is an interesting value that shows the width of a products light output to 50% of its relative power in wavelength. This is an indicator of how broad the total power distribution is, and is very interesting when comparing two sources to one another.
  • Peak and Dominant wavelength. Peak wavelength tells you where the highest output of a product is centered (in color), while dominant wavelenght tells you where it sits in CIE coordinate positions.
  • ANSI bin and CIE McAdam Ellipse values. Based on a preset standard value for the CCT a source is nearest, you can see where the measured product sits within the standard ANSI color bin, and how far off in McAdam steps it is from the CCT standard center. These are excellent tools in comparing two sources to one another of the same CCT and CRI, and along with the Du’v’ value will provide insight into what to expect in application of the products, in relation to color differences between two products.
  • Multiple source comparisons and multiple readings of a single source. The Lighting Passport allows multiple readings to be taken and compared, or collected into database. This provides direct comparisons on the meter itself of two products to one another, or of multiple readings taken in sequence within one test session. This not only allows comparisons to be made objectively on all metrics, it provides a tool for evaluating color shift over light distribution patterns. For my own use, using this meter on a goneometer rig means I can not only collect the illuminance data necessary to define light distribution, but see how the color values shift throughout that light pattern.
  • Light transmission accessory software. This small utility program is great for evaluating light transmission of materials, generating a simple report of the materials properties in both total transmission, and spectral transmission. This is a tool that every lighting meter used for design should have.
The range of information available to view on screen is excellent, clear and easy to read.

The range of information available to view on screen is excellent, clear and easy to read.

So, with that all covered, one would have to say that the product is impressive, and spot on target for what lighting professionals need in a portable and small lab environment. But, that would be missing some even more interesting features of the Lighting Passport that puts it head and shoulder ahead of the rest. Like this:

  • Separate metering head operated by wireless (Bluetooth) connection. The small head size means not having the meter body height involved in the placement of the sensor, which can be an issue in task illuminance readings, where the light source is inside 36″ of the target surface. In all the other meters with an integrated head, the body height of the meter gets in the way of gaining an accurate measurement. The Passport includes a small stand attachment that allows the meter to be set where you need it, then stand back to eliminate the influence of being in proximity of the measured result.
  • Works with ANY iOS device and Android 4.4.2 device, identically. That means phones, tablets and Pod music devices. So, if you already have an iOS or Android phone, you don’t need anything but the meter head, which slips into a pocket, to take for on-site measurement. This also means that use of a tablet sized device allows the meter and its output to be viewed easily by several people in a room, even projected onto a video monitor. In my case, I’ve connected the sensor head to my Samsung Note 3, and taken readings in a room with people viewing the results on an HDTV connected to the Note 3’s USB connector. This takes education sessions, product evaluation sessions, and general discussion and presentation to a level no other meter can match. Here’s another neat feature of this product – the interface software is open platform based, which means those with the need to create a custom interface for specialty evaluations have that available to them. This also means that updates to operating software through Android and iOS app outlets will make keeping the product current will be far easier than anything proprietary products can match.
Separating the meter head from the display is an outstanding feature that allows it to be used in a wide range of applications, and not interfere with readings.

Separating the meter head from the display is an outstanding feature that allows it to be used in a wide range of applications, and not interfere with readings. The little clip to the left attaches the head to any tablet device with a secure clamp feature.

The lighting head is compact and when mounted on its provided stand, stable for remote measurement. It is also the only part you have to carry with you to a job site, should you already have the software installed on a smart phone.

The lighting head is compact and when mounted on its provided stand, stable for remote measurement. It is also the only part you have to carry with you to a job site, should you already have the software installed on a smart phone.

The meter and its design is impressive enough to be a reason to consider it, and is very usable as a stand alone. However, on top of this, the Spectrum Genius software creates an expanded opportunity for evaluating all of the collected data in a single screen, and compare sources, or multiple readings at once. This adds a layer of utility to the metering system that really enhances its use for those doing a lot of work in evaluating application results or products for consideration in specification. It also generates very nice reports, exports data into spreadsheet worthy data sets for use in other calculations. In my case, I export the data set from multiple reading sessions to create photometric reports that are used in conjunction with the spectral reports to create all of the same data one gets from an LM-79 report, in-house, of any product I can get my hands on. That means I have been able to compare LM-79 reports provided by manufacturers to test results of product samples – with interesting results. I can also provide preliminary LM-79 evaluations of products in the design phase for customers, before they  are completed for final testing at an independent accredited lab. No more ugly surprises and re-testing issues when a product does not perform as needed or expected.

The Spectrum Genius software puts everything in one place, making evaluation quick and easy to see.

The Spectrum Genius software puts everything in one place, making evaluation quick and easy to see.

The Lighting Passport can be found in the market under the brand name Asensetek, and is sold in the USA by Allied Scientific Pro. The prices are wide open, you can order them on line, and with a range of between $1,500 to $2,500 for the meter and its attachments, plus software for free to $500, this package delivers a massive bang for the buck. This pricing is less than some of the high end white-light illuminance meters on the market, while delivering far more information. The product can also be calibrated, so can be used for precision applications and  other uses where it is important to have backing for the data collected.

Printing a report from the software to provide to customers or store as a record for comparisons is a nice feature

Printing a report from the software to provide to customers or store as a record for comparisons is a nice feature

In conclusion, I use the Lighting Passport as my go-to meter choice, and have found very little to complain about. It’s not perfect:

  • The software is a little glitchy in its display, but not so much that I find it an issue.
  • The software also creates a graphic error when creating a report using CQS, as it overlaps the data from R values with the Q values from Q7 thorugh Q15, which is truly annoying. I’m hoping this is resolved in future software updates.
  • The software also uses a dongle for security, which some will hate. I like it, as I have the software installed on both my laptops and desktop, and can move the dongle between them for use anywhere. others will find the tether objectionable I am sure.
  • The transfer of data from the meter to the software is through email or iTunes over wireless, although you can upload the data by file explorer in Android devices. This is fine with a smart phone, and works just fine with the iPod device provided in the Lighting Passport Flagship set (with wireless availability). It would be nice to be able to connect directly from a desktop through wireless to download stored files, but this is not a serious problem, and more an issue with the devices themselves – separate of the meter system. I find no compelling need to operate the meter from a desktop, as the remote head and hand held ergonomics of the data collecting device are just fine. In a lab space, use of an Apple mini-pad or other tablet device works quite well, and eliminates the need to have a computer dedicated to lab duty where it sits unused most of the time.
The package of components are well thought out, and well designed. Quality is very good.

The package of components are well thought out, and well designed. Quality is very good.

Overall, for anyone looking for a portable, high quality spectrometer/illuminance meter product, the Lighting Passport is going to be hard to beat. At its current price, I would say impossible to beat actually. More on this from Allied Scientific Pro More on the Spectrum Genius Software

Okay, so while this is not of the same caliber, or as new and cool as the spectrometers, and could be considered an obsolete product, since it is no longer made – but, there are enough of these meters around in used condition, and they have been in use for so long, that finding one with the right attachments is not a serious challenge. So why bother? To start, the basic meter frame sold new for over $1,5000, with attachments to produce various readings. I found one example on ebay, sold from a test lab that was closing, that included several useful sensor heads.

Tektronix J16 Classic

Tektronix J16 Classic


J6502 – Irradiance in uW/cm2
J6511 – Illuminance in footcandles
J6501 – Illuminance in lux or lm/M2
J6503 – Luminance in cd/m2

In new condition, this package would have cost more than $3,000, and was used on professional lab environments for years. In used condition I paid less than $250. For $350, the entire package was tested and re-calibrated to bring it up to date, which can be done for some time to come, as there are still used rebuilt units for sale now. The package delivers more options for meter reading than modern meters costing as much as this did new, so it is a decent bargain for someone so inclined to hunt for one.

Each of the sensor head/adapters includes a 1/4 x 20 boss for mounting remotely on a tripod from the meter frame, using a common 15 pin cable. Another interesting accessory is the cord set that is plugged into the top of the frame for connection to a remote voltage sensing meter, as all of the outputs are, in actuality, just meter volts calibrated to represent the value of each of the heads. This came in handy once already where I was using a temperature sensor that was connected to a multi-channel voltmeter. By adding the light meter to it, I was able to record three temperatures and the illuminance of the LED source simultaneously. Pretty handy actually.

While I realize this approach is not for everyone, for those setting up a small in-house lab at a manufacturer, with tight budgets, this may be just the ticket to capture a wide range of inputs from a single meter, that can be configured to suit various lab test needs.

As far as accuracy is concerned, I have found the readings correlary to other meters I’ve used and have in service, so have not found any instance where concern over its age, especially now that it has been calibrated. The truly nice thing about this level of technology, is the results are what they are. With no digital interpretation going on in software, you simply attach the adapter that corresponds with the meter reading you desire, align it with the product being tested, and read the results. Not much to go wrong here.

More on the Tektronix J16

The recent article: LED Bulb Efficiency Surges, But Light Quality Lags states very well the findings of the DOE and others reviewing LED retrofit lamp performance. While well stated, there are severl missing dynamic issues in the conversation that need to be included if LED is to overcome the failure of the CFL to capture the consumer market it so desperately seeks to dominate.

While efficient, there has been no great interest in the consumer market to lamps with poorer quality at higher prices.

While efficient, there has been no great interest in the consumer market to lamps with poorer quality at higher prices.

The CFL lamp has failed in the consumer market for these reasons:

  1. Light quality is poor in comparison to the far cheaper incandescent lamp. This includes color quality, distribution (photometric) pattern is poor (flood type products)
  2. Appearance and fit of the product into existing fixtures – i.e. ugly to look at, stick out of fixtures, create dark spots in shades and fixture diffusers, etc.
  3. They did not last as long as advertised. When switched frequently, the life of a CFL screw base product can be shorter than a long life incandescent. In outdoor cold climate environments, some fail within a few months. In down-lights and enclosed fixtures most fail even more quickly.
  4. They cost too much compared to incandescent of higher quality
  5. They save some energy, but have so many other liabilities the consumer does not take this seriously.
  6. Flickering starts, flicker under dimming, and 120Hz strobe effects from cheap ballast designs
  7. Slow to warm to full brightness – often taking longer to get up to full light than many products are on for in many rooms (pantry, closet, hallway, etc.)
  8. Mercury disposal concerns for some



The Tasca test mule turned 2 years in continual illuminated state this May. That’s 8,760 continuous operating hours in the cold, hot, and messy environment of the shop in which it lives. It gets abused as well, from tossing greasy rags over it to see what happens when airflow over the heat sink is cut off, to blowing coolant on it until it freezes. There have been several lessons learned in this time. For example, lumen depreciation, captured by measuring the fixture’s output, has been negligable. Losses have been less than 1.2% so far, which means the White Optics reflector and anti-reflective glass are doing their job, as is the Bridgelux ES Array LED. Temperature readings taken over this time have not changed anywhere, which indicates the internal construction attaching the thermal slug to the heat sink is durable and reliable. (more…)

The problem with revisiting something one created many years ago, is that the underlying inspiration or idea has been lost in the winds of change we all go through as we experience ife, the universe, and everything. In my case, I even have a hard time relating to how the original “thing” was even made, having forgot what tools I was using and how I made things before I surrounded myself with tools and doo-daddery.

In the case of this weeks rebuild project, I had thought that a quick trip into the garage, slam through a few pounds of metal and viola! Finished update. Yeah… right. To really get a handle on this thing took drawing the whole thing up in 3D, so I could work through the ideas and concepts without making a mess of things. In other words, this little remodel job has taken more effort than a virgin design – in that it has involved starting with a reverse engineering of the original, then design of new component within the limits of its design vocabulary.

After several days of design and iterative thinking, I think I finally have a plan to proceed. The rendering is where I ended up. I like the almost alien quality of this lamp, and its odd semi-architectural structure, so wanted to make sure that was not buried in some over-thought, overly clean addition. I think this pulls that off. I’m going to fall back on use of (2) Bridgelux 400lm LEDs, as these will produce good light, and are easy to live with in color and soft edged pattern. I’m also employing a couple of finned heat sinks, that will be left black, augmented by some machined glare/reflector cups.1/8″ stgailess rods will replace the old saggy cables.

No, I am not sure about the clips at the glass, but that can be worked out as I get the rest of the parts made up.

Time to get to work now…

I am personally exhausted with the constant barrage of PR hype clowns that have invaded the entire SSL market space, it’s like a bad virus that feeds on active brain cells like some zombie brain eating monster that insists on howling at the top of its lungs whenever it thinks its done something interesting. The lighting market has always had a little bit of a stomach pit inducing illness, with claims made that are silly and obviously not founded on the reality normal humans are forced to exist within. However, what has been happening over the last 5 years coming from the SSL universe is an all new illness, it’s far more aggressive, and more painful.

Part of this is due to a change in paradigm regarding marketing. In the past, lighting companies employed in-house marketing people, who used local marketing agencies to place ads, or do some graphic work on catalogs. I know, as this is the function I performed for three leading product manufacturers for almost 20 years. We communicated to our target audience through reps, catalog sheets, web sites, trade shows, and an occasional letter campaign. Few actually used big PR agencies with broad marketing campaigns aimed into the wind. Know why? Simple, they are really expensive, so were never even considered as affordable, let alone useful. Most have zero knowledge of the market, think that that lack of knowledge is not an issue, and cost more for a few press releases than most total marketing budgets for an entire year. It takes the funding of venture capital to back a company with the funds needed to spend what they do on PR, while at the same time producing the need to broadcast their message to the world at large to support investors who are outside this market. The result, we now have a pile of non-lighting PR agencies with bullhorns, blaring whatever their customer companies (also non-lighting people) tell them is news to our once relatively quiet lighting world. The resulting din is akin to a neighbor who can’t seem to listen to music without cranking the dial up on an expensive amp to “11”. To make matters worse, the music selection is like bump-bump rap, the same noise, over and over and over, drumming and pounding messages of efficacy world records and earth shattering performance that will save the planet from certain destruction by incandescence, and fluorescence.

To make all of this even more painful, is that this virus is unpredictable. One day I get pounded with three releases that when exposed to the light of day squirm off the screen and hide under a table.  You’ve seen them, the claims of a 12W LED product with a CBCP of 4,000, and 800 lumens beating a 70W Ceramic Metal Halide producing 22,000 CBCP and 2,100 lumens – or the claims that the LEDs used will last a lifetime, or that if everyone used the product, our teeth would become whiter, and our skin smoother. Anything goes here, from claims of efficacies of 180 lumens per watt (at some stupid CCT), to performance comparisons that are simply fiction no matter how you look at it. Then, the next day, you get an interesting release about a color control system that, well, oddly enough… actually provides something useful and interesting. Unfortunately the ratio of garbage to inspiration is heavily weighted toward the landfill side of the formula.

The cultural shift that surrounds solid-state is not founded on anything the electronics gurus believe. Contrary to the impression that we are slow-witted laggards, we lighting people will absorb and put SSL, to use,  just as we have every other useful technology that has come before it. When the SSL providers actually produce lighting product (not just the LEDs, not just an electronic gadget, but a real live luminaire product) we will find uses for it, IF it works, produces a benefit beyond just using LEDs, and if the price makes sense in balance to the benefits realized. By this, I mean benefits in lighting terms, as we define it, not in terms of PR baloney, engineer pipe dreams, or marketing department trickery – I mean in real terms, using real data, real photometric tests, etc… The electronics gurus give us too little credit here, and don’t see where the real culture clash is founded – a huge difference in the perception of money.

The difference between an SSL start up and a lighting industry start up is spectacular. The vast majority of lighting industry startups began from the personal checkbooks and savings accounts of individuals, who worked their way into a market one step at a time, sometimes failing, sometimes succeeding, and rarely with much fanfare from expensive marketing entities from New York or Chicago executive towers. We are talking about real world, grass roots, dirty hands startups. Solid-state startups, at least by the time we see them, have a lot more money at hand… a lot. Most have more cash from venture capitalists than most lighting company startups realize in total sales after 20 years of effort. Having a starting fund of $20M is not unusual in an SSL startup, while I personally know of dozens of lighting manufacturers who started with less than a few thousand, scraped out of personal savings.

The result of all of this, like the invasion of South America by the Spaniards, is the spread of SSL Hype Clown Virus. A lyric from a recent Pink! album (Funhouse) illustrates this well… “This museum’s full of ash, once a tickle, now a rash… this used to be a fun house, now its filled with evil clowns….” Unfortunately, behind all this overly aggressive and ridiculous press is a population of really creative technicians, who are making strides and inventing new things we will all come to put to work. It’s kind of like having a best friend married to a loud and obnoxious partner – in the end you avoid them both to maintain sanity. There is a part of this happening in the adoption cycle of SSL. There are more than a few potential customers who are so sickened by SSL HCV they can’t see the great technology behind it.

There needs to be some effort to vaccinate this market from the most aggressive forms of the PR sickness. This can only come from the solid-state providers themselves, reigning in what has become a real evil-clown parade, leaving behind horse apples and associated stench. We lighting people are not going to respond to this positively. We have heard so much trash talk, been promised the impossible, and seen so many ridiculous claims, that we’re becoming deaf to the noise, reducing the effectiveness of any releases going forward anyway. Might as well try a new angle – clarity, realistic statements, backed by independent test results and data we can all put to use. Fire the high power marketing agencies, spend the money on more product, and communicate to us all like the professionals we are.