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02/12/2008 1/8 FC series lenses for Cree XR7090 LEDs
FC Lens series
for Cree XLamp® 7090 XR and XR-E LEDs
High efficiency
4 beams available
Easy assembly
The FC lens offers low-profile lenses
specifically designed for the XLamp®
7090XR and XR-E LEDs
(1)
from Cree.
A software-optimized aspheric profile
enables the generation of several different
beam output patterns: narrow, medium,
elliptical, and wide beams.
The high collection efficiency reaches
85% of the total flux emitted by the LEDs.
Lens holders are available in black, and
provide the proper alignment between the
LEDs and the lenses, and set the correct
distance between the lens and LED.
The lens holder can be glued to the PCB
to provide a secure assembly.
Typical applications are:
• Reading lamps
• Signs
• Architectural Lighting
• Street Lights
Cree® XLamp is a trademark of Cree, Inc. For technical
information about these LEDs please refer to the Cree® XLamp
datasheet or visit http://www.cree.com/products/xlamp.asp or
http://www.cree.com/products/xlamp7090_xre.asp
FRAEN CORPORATION FRAEN S.r.l.
80 Newcrossing Road Via Stelvio, 12
Reading, MA 01867 20019 Settimo M. (MI) – Italy
Phone: 781.205.5300 Phone: +39-02-35.456.1
Fax: 781.942.2426 Fax: +39-02-335.456.239
optics@fraen.com info@fraen.com
Website: www.fraensrl.com
For ordering information, please contact:
NAFTA Countries
ARROW
Telephone: 1-888-9LIGHT1
email: lightingsolutions@arrow.com
European Countries Please contact Fraen S.r.l. for
distributor’s information
Email: info@fraen.com
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02/12/2008 2/8 FC series lenses for Cree XR7090 LEDs
General Characteristics
________________________________________________________________
Lens Material
Holder Material
Operating Temperature range
Storage Temperature range
Optical Grade PMMA
PC, black color
-40deg C / + 80 deg C
-40deg C / + 80 deg C
Average transmittance in visible spectrum (400 – 700nm) >90%, as measured using 3mm
thick Optical Grade PMMA.
Please note that flow lines and weld lines on the external surfaces of the lenses are
acceptable if the optical performance of the lens is within the specification described in the
section “OPTICAL CHARACTERISTICS”
IMPORTANT NOTE – Lenses handling and cleaning:
• Handling: Always use gloves to handle lenses and/or handle the lenses only by the
flange. Never touch the outside surfaces of the lenses with fingers; finger oils and
contamination will absorb or refract light.
• Cleaning: Clean lenses only if necessary. Use only soap and water to clean the
surfaces and lenses. Never expose the lenses to solvents such as alcohol, as it will
damage the plastic.
Scope
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This datasheet provides information about the new FC series lenses:
• FC-N2-XR79-0R
• FC-M2-XR79-0R
• FC-W2-XR79-0R
• FC-E2-XR79-0R
The N2 and M2 part numbers have replaced the N1 and M1 part numbers:
• FC-N1-XR79-0
• FC-M1-XR79-0
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02/12/2008 3/8 FC series lenses for Cree XR7090 LEDs
Optical Characteristics – Beam Angle (degrees, Full Angle)
________________________________________________________________
Lens Part Number
Type of lens Cool
White Warm
White
Blue
Green
Red
FC-N2-XR79-0R Narrow beam
8 8 12 12 12
FC-M2-XR79-0R Medium beam
21 20 22 22 22
FC-W2-XR79-0R Wide beam
29 28 28 28 28
FC-E2-XR79-0R Elliptical beam
8 x 44 8 x 44 13x45 13x45 13x45
FC-N1-XR79-0
(5)
Narrow beam
9 - 9 9 9
FC-M1-XR79-0
(5)
Medium beam
28 - 22 22 26
(1) The typical divergence varies with LED color due to different chip size and chip position tolerance. The
typical total divergence is the full angle measured where the luminous intensity is half of the peak value.
Optical Characteristics – On-Axis Intensity (candela/lumen)
________________________________________________________________
Lens Part Number
Type of lens Cool
White Warm
White
Blue
Green
Red
FC-N2-XR79-0R Narrow beam
27 27 18 18 19
FC-M2-XR79-0R Medium beam
4.1 4.1 2.9 2.9 3.3
FC-W2-XR79-0R Wide beam
2.4 2.4 1.9 1.9 2.4
FC-E2-XR79-0R Elliptical beam
4.8 4.8 3.5 3.5 3.5
FC-N1-XR79-0
(5)
Narrow beam
21 - 15 17 10
FC-M1-XR79-0
(5)
Medium beam
2.7 - 3.3 3.7 1.9
(2) To calculate the on-axis intensity, multiply the on-axis efficiency of the lens (cd/lm) by the total flux of the
Cree XLamp 7090® XR and XR-E LED used. See “Illumination Calculations” below. For more detail on
flux binning please check the Cree LED datasheet at http://www.cree.com/products/xlamp.asp
(3) Luminous intensity depends on the flux binning and tolerances of the LEDs. Please refer to the Cree
XLamp datasheet for more details on flux binning and mechanical tolerances.
(4) Typical illuminance measured in lux per lumen (E) with typical Cree
7090 XR-E LED. To estimate the
illuminance in lux, multiply the typical illuminance E by the flux in lumen of the LED used. See “Illumination
Calculations” below.
(5) FC-N1-XR79-0 and FC-M1-XR79-0 have been replaced by FC-N2-XR79-0R and FC-M2-XR79-0R.
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02/12/2008 4/8 FC series lenses for Cree XR7090 LEDs
I
llumination Calculations
________________________________________________________________
To calculate peak candela: Find the central spot “on-axis intensity” value in the table above, then
multiply this value by the lumens output from your LED (refer to the XLamp LED datasheet
http://www.cree.com/products/pdf/XLamp7090XR-E.pdf
or
http://www.cree.com/products/pdf/XLamp7090XR.pdf
for nominal lumens values). Or for a more accurate calculation, refer to the intensity binning tables
http://www.cree.com/products/xlamp_docs.asp
.
Example calculation:
If the Fraen narrow beam lens FC-N2-XR79-0R is used on a cool white Cree XR-E LED at 350 mA,
the typical luminous flux of the LED is 80 lumens:
The calculation is: (27 candela/lumen) x (80 lumens) = 2160 candela peak on-axis.
The beam angle specified in the table above is 8 degrees full beam-width measured at half-peak.
This means at 4 degrees off-axis (half of 8 degrees), the intensity should be half of 2160 candela, or
1080 candelas.
1 candela at 1-meter distance produces 1 Lux. This means the peak intensity at 1 meter will be 2160
lux. The intensity decreases as a function of the distance squared, so at 2 meters the peak intensity
will be 2160 / (2
2
) = 540 lux. At 3 meters distance, the peak intensity will be 2160 / (3
2
) = 240 lux.
Mechanical Characteristics
________________________________________________________________
Figure 1. Identifying the lenses by their front views
FC-N1-XR79-H FC-M1-XR79-H
FC-N2-XR79-HRF FC-M2-XR79-HRF FC-W2-XR79-HRF FC-E2-XR79-HRF
Replaced by
FC
-
N2
-
XR79
-
HRF
Replaced by
FC
-
M2
-
XR79
-
HRF
A mild texture has been added to the
micro-lenses on the M2 (medium beam)
and W2 (wide beam) lenses to improve
evenness of the light output.
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02/12/2008 5/8 FC series lenses for Cree XR7090 LEDs
The FC series lenses are available either assembled to a holder or without a holder. The holder
provides the correct alignment (concentricity, height, and orientation) of the lens to the LED.
Orientation control is important for the elliptical beam lens.
Figure 2. Correct vertical distance between FC lens and 7090 XR-E LED
Figure 3. Elliptical beam orientation
NOTE: If the FC lens is used with no lens holder, the user must provide a mechanical method to
set the correct distance between the lens and LED. For example, the lens flange can be
located in the lamp housing to center the lens to the LED and establish 13.9 mm from the
lens flange to the user’s PC board. For N2, M2, W2, E2 lenses, the lens touches the LED.
Toler
ances: +/
-
0.2 mm
FC-N2-XR79-0R
NOTE: The elliptical beam lens
produces a beam shape that
is perpendicular to the
microlens pattern on the
output face of the lens. The
lens holder is designed to
align the elliptical pattern with
the rectangular shape of the
Cree LED substrate. It is
important to consider the
orientation of the LEDs and
the desired elliptical beam
orientation when designing
the printed circuit board
layout.
To produce a horizontal elliptical beam, the lens needs to be
orientated such that the micro-lenses are positioned vertically.
The elliptical beam lens assembly (with holder) will only fit the
Cree LED in this orientation (with elliptical beam and
rectangular LED substrate aligned). The LED orientation on
the PC board should be coordinated with the beam orientation.
Elliptical beam
and lens gate
are horizontal.
The micro-lens
pattern is vertical.
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02/12/2008 6/8 FC series lenses for Cree XR7090 LEDs
Figure 4. Installation of lens assembly onto Cree LED
The new FC-N2-XR79-HRF (and M2, W2 and E2) lens assemblies will fit onto the Cree LED at only 2
orientations: 0 degrees and 180 degrees. The bottom of this new –
HRF lens holder has a rectangle shape
to control lens orientation (importan
t for “E2” elliptical beam lens application). After installation, the bottom
of the holder should be at the same datum/plane as the bottom of the Cree LED.
Small crush-ribs inside the
round hole will center the
lens assembly on the round
body of the Cree LED.
The lens assembly can be secured to the PC board by using glue or
silicone RTV. To avoid glue on the lens and LED, apply it along the
outside diameter edge, or apply a very thin film on areas shown in green.
CAUTION: Do not use instant glue (containing cyanoacrylates). Always
test the glue on a sample assembly and check the results and
performance 24 hours later. Some adhesives produce fumes that will
damage the surfaces of the plastic lens, lens holder, or LED.
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02/12/2008 7/8 FC series lenses for Cree XR7090 LEDs
Figure 5. Overall dimensions of FC-_2-XR79-HRF series lens assemblies
The new FC-_2-XR79-HRF assemblies
(shown at right) are ~ 0.4 mm larger
diameter than the previous FC-_1-XR79-H
assemblies shown below.
FC-N1-XR79-H
FC-N2-XR79-HRF
“Flat-top” lens “Curved-top” lens
Tolerances: +/
-
0.2 mm
Replaced by
FC
-
N2
-
XR79
-
HRF
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02/12/2008 8/8 FC series lenses for Cree XR7090 LEDs
Ordering part numbers
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FC-_2-XR79-__
Published by Fraen Corporation.
All technical data contained in this document are properties of Fraen Corporation and may change without
notice.
Published by Fraen Corporation.
All data contained in this document is the property of Fraen Corporation and may change without notice.
Rev Date Author Description
05 16 October, 2007 C. Jones Texture added to M2 and W2 lenses to improve
homogeneity (evenness) of light output.
04 05 September, 2007 C. Jones Replaced N1 and M1 with N2, M2, W2, and E2 family.
Added figures 2,3, 4, and 5 and illumination calculations.
03 26 March 2007 D. DeGaetano Added Wide and Elliptical timing of official release
02 4 December 2006 D. DeGaetano Revised holder mechanical drawing
01 27 November 2006 D. DeGaetano Official Datasheet
00 10 October 2006 D. DeGaetano Preliminary Datasheet
0R: Lens alone (no holder)
HRF: Lens with black PC holder
Caution: If using lens alone (with no holder), lens
alignment and spacing must be set by the
user. See Figure 2.
N: Narrow beam
M: Medium beam
W: Wide beam
E: Elliptical beam Caution: The orientation of the
elliptical beam lens is controlled
by the lens holder and the LED
orientation (see Figure 3).
