Color measurement: instruments keep on shrinking in size and price.

There is a whole new balance between price, performance, and convenience in color instruments today. For example, the advent of affordable handheld spectrophotometers was the major breakthrough of the 1990s (see PT April, '94, p. 27), particularly for production-floor color quality control. The most recent models of these instruments have grown even smaller, lighter, faster, and more accurate.

Newer benchtop instruments, too, are more compact, more automated, and much lower in cost than their predecessors. A new crop of entry-level benchtops carries price tags comparable to those of some portables.

There has also been considerable advancement in software packages for color formulation and quality control. Most, if not all, new introductions are Windows-based. They allow custom configuration of display screens and show electronically generated simulations of color standards and sample formulations under various lighting conditions. Other new features that allow for easier data manipulation include spreadsheet capability, e-mail data transfer, and ability to transfer data to and from portable spectrophotometers.

MORE POWER IN YOUR HAND

When it comes to a portable instrument, there appears to be little advantage to a colorimeter today, when greater accuracy is available at similar cost in a spectrophotometer. Colorimeters characterize color by means of three filters to quantify light in each of three broad color bands - red, green, and blue. Spectrophotometers use a grating and array detector to generate 16-31 discrete measurements by dividing the visible spectrum into narrow bands of 10-20 nm. Consequently, they provide more precise color discrimination and superior inter-instrument agreement.

Portable colorimeters are still less expensive, although not much so. They generally cost $2500-6000. Prices of portable spectrophotometers range from $3500 to $7000 on the low end and $7500-10,000 on the high end. (The latter figure is down from $10,000-12,000 three years ago.)

All of these self-contained portable instruments store color standards and compute and store color-measurement data. They are said to be ideally suited to pass/fail color evaluation. Calculated L,a,b or [Delta]E values can be viewed on their LCD displays when you select the desired color-space calculation.

Most portables don't include a transmission mode for measuring clear plastics. Two exceptions are Minolta's CM-508d, which has been around for a few years, and the new MiniMatch from Spectronic Instruments (formerly the Diano division of Milton Roy). However, even these units offer only specular transmission mode, while higher-end benchtops have both specular and diffuse transmission capability - the latter being considered more precise.

Many new or upgraded handheld spectrophotometers now display actual spectral curves. Moreover, they have menu-driven software that reduces errors and improves measurement consistency through features such as auto-save, temperature sensing, calibration prompting, and auto-error detection. All allow direct connection to a printer or have an RS-232 interface for data transfer to a PC.

Cost of a portable spectrophotometer together with a PC and the latest quality-control and color-formulation software - a setup that approaches the performance of benchtop units can run $18,000 to $30,000.

NEW OPTIONS IN BENCHTOPS

Although portable spectrophotometers have gained popularity at the expense of benchtop models, several suppliers recently have introduced very compact, entry-level benchtop units with prices of $7000-10,000, close to those of higher-end portables. Many of these units have the same capabilities as the portable units most measure only reflectance, not transmission.

Macbeth product manager Mike Beering says these value-engineered. QC-grade, compact benchtop units do have advantages over portables: "As these benchtops are driven by PC software, they can offer greater flexibility in using the color data collected. The entry-level benchtops can also serve as satellite systems [for compatible high-end] reference instruments." On the other hand, Beering advises that "users who require precise, laboratory reference-grade reflection and transmission measurements need to go with a higher- end benchtop. This is important in situations like global data sharing and color formulation."

Marketing manager Terry Downes of Datacolor International also defends the new QC-grade benchtops in comparison with portables: "The benchtops are more rugged and don't get damaged or lost. Also, portables have limited display and software capability. In general, software is easier to use on benchtops since you have a whole keyboard versus a few button options to do color analysis. Because of these inherent limitations of portable units, many people are connecting them to a PC and using them essentially as benchtops."

Minolta product manager Elaine Becker says a key advantage of bench-tops is that they can use different apertures (e.g., 25, 8, or 3 mm) to accommodate large or small samples, whereas portable units typically limit you to one aperture. (A couple of suppliers Byk-Gardner and ColorTec - offer portables with various interchangeable apertures.)

Even the newest top-of-the-line benchtop spectrophotometers have moved toward smaller footprints and lighter weights. Many of these units now feature more computer control of the lens, uv filter, and specular port, says Minolta's Becker. The ability to calibrate the uv component of the color spectrum is an important trend for measuring fluorescent colors accurately. Higher-end benchtop instruments currently cost $15,000-20,000, down from 825,000-40,000 earlier in the decade.

RELATED ARTICLE: What's New in Color Instruments & Software

Portable Instruments

Byk-Gardner USA, Columbia, Md. - The company's first portable spectrophotometer, called Handy-spec, is said to be suitable for production-line pass/fail qualification and reading spectral curves, elliptical tolerance graphs, multiple color scales and color differences, and multiple colorant-strength routines. Measurements can be transferred directly to Windows-compatible spreadsheets. QC, color matching, and batch correction are performed with Gardner's Match-ware and toolkit software. Handy-spec sells for $8795.

ColorTec, Clinton, N.J. - The firm has redesigned its ColorTec PCM Spectral Analyzer, which measures light at 16 points across the visible spectrum like a spectrophotometer, although color analysis is provided in tristimulus colorimetric terms. While most color instruments use white tungsten or xenon light sources, this one utilizes lower-cost, long-life LEDs. The PCM (Personal Color Meter) now uses a greater number of LEDs to cover the entire visible spectrum.

The PCM has two apertures of 3 and 8 mm and a 45/0 [degrees] sensor. It weighs under 1 lb and reportedly performs at least as well as most portable filter colorimeters. It sells for $2500.

ColorTech also updated its ColorTec-SCM, a 0/45 [degrees] portable spectrophotometer and gloss meter designed for both QC and color formulation. This dual-purpose unit was previously known as Spectro/plus and was manufactured by Color and Appearance Technology, Inc. (now defunct). ColorTec has redesigned it with new filters and updated electronics. It has two apertures of 20 and 5 mm and sells for under $7000.

Macbeth Div., Kollmorgen Instruments Corp., New Windsor, N.Y. - Sphere-based Color-Eye 580 spectrophotometer has the same optical configuration as the new Color-Eye 2180 benchtop (discussed below). It is said to provide excellent measurement accuracy and agreement with Macbeth's high-end Color-Eye 7000 and newer 7000A. Users can therefore create color-control networks that include formula laboratories and QC departments at various locations. Users also can benefit from compatibility with suppliers and vendors using Color-Eye 7000A instruments. Color-Eye 580 sells for under $8000.

Spectronic Instruments, Inc., Rochester, N.Y. - MiniMatch spectrophotometer is said to combine bench-top instrument performance at the price of a portable. It performs reflectance and transmittance measurements in either a standalone mode using its built-in software, or interfaced to a PC with the company's new WinMatch QC and formulation software for Windows 95.

This is described as a dual-beam laboratory-grade instrument with a tungsten light source, 45/0 [degrees] illumination, and measurements in 10-nm increments across the 400-700 nm range. Repeatability is said to be 0.04 CIE L,a,b or [Delta]E units. Weighing only 3 lb, it has a base price of $3500. Options include a built-in transmittance cell (which brings the price to $3950) and ability to insert the unit into a PC docking station, which transforms MiniMatch into a benchtop.

This instrument is sold under the Colorport name by Color Instruments, Inc., Ft. Lauderdale, Fla.

X-Rite, Inc., Grandville, Mich. - MA68II multi-angle spectrophotometer for measuring metallic, pearlescent, and other special-effect colors, is said to offer better inter-instruments agreement and repeatability than earlier versions. It incorporates an optical system that provides simultaneous measurement at all angles with increased spectral resolution. Price is in the range of $20,000-25,000, including MetalliX-QC Windows software.

Also new is a portable sphere-type spectrophotometer that features a dropped aperture for measuring color in shallow recesses. The aperture (8 or 16 mm) protrudes from the sphere of the instrument, which takes measurements every 10 nm. It's priced around $10,000.

QC-Grade Benchtops

CVI Laser Corp., Albuquerque, N.M. - This producer of laser optics and optical instruments has entered the field of color measurement with two low-cost benchtop spectrophotometers. Both use a CCD photodetector array and grating for spectral measurement to a resolution of 5 nm. With Windows software that displays spectral curves and color-difference readings, these units measure percent transmission or reflection normalized to any reference illuminant.

SpectraMatch GT is a fiber-optic instrument designed for on-line production, QC, and lab environments. Said to be rugged and compact (measuring 2.75 x 4.5 x 6.875 in. and weighing 2 lb), this system includes the detector, PC data-acquisition A/D card, and fiber-optic probe. The probe measures reflectance in areas as small as 1.2 mm. It is priced at $2249.

The SpectraMatch SM-100 benchtop is identical to the GT model in technology although it does not use fiber optics and is larger (6 x 10 x 8 in., weighing 5 lb). It is aimed at lab or QC work and costs $2995.

Datacolor International, Lawrenceville, N.J. - DataFlash 100 is designed for production environments. Said to be rugged and compact (12.6 x 7.5 in.), it has just one available aperture size. It employs the same grating and photodetector as the company's higher-end spectrophotometers (SpectraFlash 600 and 300). It also measures gloss. All operations are accomplished through a host PC. It sells for under $10,000.

Macbeth Div., Kollmorgen Instruments Corp., New Windsor, N.Y. - Sphere-based Color-Eye 2180 spectrophotometer has the same optical configuration as the new Color-Eye 580 portable (discussed above). Both are said to provide excellent measurement accuracy and agreement with Macbeth's high-end Color-Eye 7000 and newer 7000A. The 2180 sells for under $8000.

Minolta Corp., Ramsey, N.J. - CM-1300 spectrophotometer is an entry-level unit said to be very comparable to Macbeth's new Color-Eye 2180 discussed above. It sells for under $10,000.

High-End Benchtops

Macbeth Div., Kollmorgen Instruments Corp., New Windsor, N.Y. - New Color-Eye 7000A is said to build on the reliability and inter-instrument agreement of the older Color-Eye 7000. Model 7000A is a dual-beam spectrophotometer whose new automated features include motorized, adjustable uv illumination control that stores up to three settings. An automatic calibration routine adjusts the uv content to that found in natural D65 daylight. A motorized specular insert allows measurement of gloss or texture effects. Touchscreen displays shows instruments status at a glance. The unit comes with Optiview Lite color QC software and optional Pro-Palette formulation package.

Minolta Corp., Ramsey, N.J. - CM-3700 is a sphere-type spectrophotometer that has three measuring apertures (25, 8, and 3 x 5 mm), continuously variable uv illumination, and gloss measurement. It has a 360-740 nm range and 10-nm measuring intervals, as well as diffuse transmittance measurement and pulsed xenon illumination.

Continuous On-Line Measurement

HunterLab, Reston, Va. - Qual-Probe XR on-line colorimeter is an enhanced version of the original Qual-Probe unit. It includes a sensor for photometric and height data, and has a support unit that provides input-output functions and power conversion. The sensor can be operated by a host PC or hand-held keyboard terminal. Windows software for a host computer provides prompts for entering, storing, and receiving data.

Designed to withstand harsh industrial environments, the XR can continuously monitor color of compounded pellets and other extruded or molded parts as they are produced. Color information is received in real time, allowing users to spot off-color trends and correct the process. While not as accurate as high-end on-line spectrophotometers (such as HunterLab's Spectra-Probe unit) that sell for over $50,000, this is said to be a cost-effective option for color-difference QC monitoring. It costs $10,000-20,000.

New Software

ColorTec, Clinton, N.J. - ColorSoft 32-bit formulation, batch-correction, and QC software for Windows is said to allow fast matching and improved batch correction, as well as elliptical color tolerancing for quality control.

Datacolor International, Lawrenceville, N.J. - ColorTools QC software for Windows uses artificial intelligence to create pass/fail color tolerances. It does so by "learning" the preferences and color-acceptance criteria of each customer. The package allows users to format printouts to individual needs and reportedly shares data easily with other software and computer systems. Available in entry-level and more sophisticated versions, it is priced in the $1000-5000 range.

Minolta Corp., Ramsey, N.J. - SpectraMatch Windows 95 formulation software is available in four different levels of sophistication and price. The color-matching screen is custom configured for each user. The package calculates color differences for three illuminants and displays the spectral curve of the predicted match as well as a simulated comparison of the match versus target color for three lighting conditions. Priced at $700011,000, the package includes a new Windows version of the company's SpectraQC module.

Spectronic Instruments, Inc., Rochester, N.Y. - WinMatch QC and formulation software for Windows 95 allows the user to define screens and reports and export data for analysis. It is priced from $6500 for the QC module alone to $9500 for the full QC and formulation package.

X-Rite, Inc., Grandville, Mich. - Plastic-Master formulation software for Windows interfaces with both 0/45 [degree] and spherical-geometry spectrophotometers and includes the QA Master quality-control program. Plastic-Master displays match results as spectral curves, CIELAB plots, visual color simulation, and tabular data.