Reflection Measurements

Flame color measurement system - Spectrecology — Reflection measurement using a fiber optic probe at 45 degrees – Spectrecology

% Reflection or reflectance is measured as the ratio of light reflected from a sample to light reflected from a reference material. When measuring specular reflectance, it is usually expressed in a percentage scale (%R). Fixtures and probes are used to define the illumination and reflected light angles, allowing for the measurement of specular (mirror like) and/or diffuse reflection. In a typical setup, the light source and spectrometer are connected by optical fibers to the reflection measurement fixture. In the illustration the fixture is a fiber optic probe held at 45 degrees to the sample. The system can be purchased as a kit.

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45/45 reflection accessory by Spectrecology — REF fixture set for 45/45 specular reflection with collimating lenses – Spectrecology

SE-REF-KIT 45/45/90

This is an aluminum fixture for looking at reflection from flat surfaces. There are 3 ports to allow for illumination at 45, 90 and 135 degrees. The ports accommodate screw in fiber optic collimators (2 are included with the kit) or black plugs to block light. An additional adapter will hold a 1/4″ OD reflection probe. The ports fit our SE-112689 collimator with quartz, sapphire or AR coated lenses. The ports also accommodate the 74-UV and 74-ACR style lenses.

SE-REF-KIT specifications

Model Number	SE-REF-KIT
Materials	Fused Silica, Aluminum (black anodized)
RoHS Compliant	Yes
Max. Bake Temperature	80 °C
Max. Operating Temperature	80 °C
Max. Vacuum Level	Air Service
Length / Height	2.30 Inch
ID	0.25 Inch
OD	1.00 Inch
Operating Wavelength	250~2000 nm

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R400-7 and R-600-7-UV-SWIR Fiber Optic reflection Probes

The 6 around 1 fiber reflection probe is multi-purpose. It can be used to measure specular or diffuse reflection from a surface, diffuse reflection from liquids, tissue and other translucent materials and fluorescence.

Probes are available in any size fiber, but the R400-7-UV-VIS (or VIS-NIR) or our new R600-UV-SWIR probes are our most popular. They have a 3″ ferrule, 1/4″ OD and 2m long fibers that are bifurcated at the halfway point. These probes can be used with holders such as the SE-REF above, or the RPH-1, to hold it at 45 or 90 degrees. A white (diffuse) or specular reflection standard and a light source completes the setup.

Fiber types include XSR for UV (extreme solarization resistance, 190-900nm), VIS-NIR (350-2200nm) and UV-SWIR (200-2200nm)

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The SE-112802 30 degree reflection adapter provides a large area flat quartz window to accommodate measuring powders, or soft surfaces that must be pressed into a flat surface. This provides essentially “dark field” reflection spectra by eliminating specular reflections in the measurement plane.

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Reflection Probe

R400 Reflection Probe Specifications

Engineering Specifications	Premium-grade Reflection Probes
Probe ferrule material:	Stainless steel
Probe ferrule length:	76.2 mm (3″)
Probe ferrule diameter:	6.35 mm (1/4″) unless otherwise noted (3.175 mm / 1/8″ for QR600 probes)
Probe fiber bundle:	6 illumination fibers around 1 read fiber
Numerical aperture:	0.22 ± 0.02 (equivalent to an acceptance angle of 24.8° in air)
Jacket:	Standard fibers: Silicone-coated steel monocoil with a Nomex braid for superior strain relief and protection
Jacket:	“-BX” fibers: Stainless steel BX
Connectors:	Precision SMA 905 with knurled ferrule
Length:	2 m
Breakout:	Midway point of assembly at 1 meter
Fiber core size:	200 – 600 μm (see product variations table for options)
Wavelength range:	XSR, SR, UV/VIS, VIS/NIR (see product variations table for options)
Fiber buffer:	See Fiber Bend Radius and Mechanical Specifications for details
Bend radius:	See Fiber Bend Radius and Mechanical Specifications for details
Operating temperature:	-20 °C to 80 °C

Probe attachment

Large Area Reflection Probe Adapter specifications

Quarter reflection probe adapter, tilted 30° / 60° (from normal / optical axis) with large contact area 25mm diameter fused silica lens is ideal for large specimen study.

Model Number	SE-112802
Materials	Fused Silica, Aluminum (black anodized)
RoHS Compliant	Yes
Max. Bake Temperature	80 °C
Max. Operating Temperature	80 °C
Max. Vacuum Level	Air Service
Length / Height	2.30 Inch
ID	0.25 Inch
OD	1.00 Inch
Operating Wavelength	250~2000 nm

The spot size for reflection off a surface, and the active volume for fluorescence or back scatter vary with distance. Initially the signal increases as the overlap region grows. Then the signal decreases as the distance to the sample increases.

diffuse reflection R400 — Diffuse reflection probe optics – overlap volume of illumination and read fibers varies with distance – Spectrecology

reflection probe sampling depth — Backscatter – reflection signal increases with the distance to the probe tip, then decreases. – Spectrecology

Integrating Spheres

ISP-R reflection integrating sphere — Integrating spheres for reflection measurements – Spectrecology

Integrating spheres are used to acquire reflection spectra from 180 degrees. The typical setup is to have a collimated viewing angle of ~8 degrees from normal and diffuse illumination from a baffled light source in the sphere. A removable light trap at the opposite 8 degree angle can be used to eliminate specular reflection. ISP-R series fiber optic integrating spheres couple to Ocean Optics spectrometers to measure the total integrated reflectance of surfaces placed against the sphere’s sample port. ISP-R integrating spheres are well-suited for measurement of opaque or highly directional samples. The spheres are available in 6 mm and 8 mm sample port diameters and gloss-trap options are available that allow you to measure the specular component of the total integrated reflection. Versatile – adaptable for diffuse or specular measurements High reflectivity – PTFE sphere coating is >98% reflective from 400-1500 nm Multiple options – available with sample port diameters of 6 mm and 8 mm

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Integrating Sphere Secifications

Engineering Specifications	ISP-30-6-R	ISP-50-8-R	ISP-50-8-R-GT	ISP-80-8-R
Dimensions:	59 mm diameter x 58 mm height	80 mm diameter x 78 mm height	80 mm diameter x 78 mm height	107 mm diameter x 117 mm height
Weight:	330 g	730 g	743 g	1,650 g
Spectral range:	200-2500 nm	200-2500 nm	200-2500 nm	200-2500 nm
Sphere diameter:	30 mm	50 mm	50 mm	80 mm
Sample port diameter:	6 mm	8 mm	8 mm	8 mm
Sphere coating:	PTFE	PTFE	PTFE	PTFE
PTFE reflectivity:	>98% (400-1500 nm)>95% (250-2500 nm)	>98% (400-1500 nm)>95% (250-2500 nm)	>98% (400-1500 nm)>95% (250-2500 nm)	>98% (400-1500 nm)>95% (250-2500 nm)
Reflectance measurements:	Specular and diffuse	Specular and diffuse	Diffuse or specular and diffuse	Specular and diffuse
Gloss trap:	No	No	Yes	No
Connector:	SMA 905	SMA 905	SMA 905	SMA 905

ISP-REF — Integrating sphere for measuring diffuse hemispherical reflection

Stage-RTL

RTL-STAGE — Multi-purpose sample stage for reflection and transmission using fiber probes, lenses and/or integrating spheres – Spectrecology

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The Stage-RTL-T is a clever sampling system that couples to Ocean Optics spectrometers and accessories for reflection and transmission measurements of samples ranging from organic materials such as grains and fertilizers to man-made materials including plastics, coatings and semiconductor wafers. Thanks to its variable x-y axis rail design and adjust able platform, the Stage-RTL-T can be configured for several setups: Attach an Ocean Optics ¼” (6.35 mm) OD reflection probe and position the probe for 90° measurements. Position collimation lenses to measure transmission at 90° or reflection at 45°. Add an optional integrating sphere adapter (ISP-RTL-ADP) to make diffuse reflection measurements using 30 mm and 50 mm diameter integrating spheres.

Multipurpose – adjustable for transmission and reflection measurements Sample parameters – ideal for flat substrates and large specimens Materials measured – everything from coatings and semiconductor wafers to vegetation and animal tissue

Stage-RTL specifications

Engineering Specifications	STAGE-RTL-T
Base dimensions:	206.3 mm diameter
Sample area dimensions:	152.4 mm diameter
Weight:	4.5 kg
Rail height:	Adjustable to 400 mm
Components:	Sample plate, rail, adapter, collimating lenses (2) and light trap
Collimating lens wavelength:	200-2000 nm
Stage material:	Anodized aluminum
Integrating sphere adapter (optional):	Item ISP-RTL-ADP, for attaching 30 mm or 50 mm ISP-series spheres

Reflection Standards

Diffuse Standards for Reflectance Measurements

We offer two types of diffuse reflectance standards. The WS-1 uses a PTFE optical diffuser, a Lambertian material distinguished by its white matte finish and reflectivity >98% from 250-1500 nm and >95% from 250-2200 nm. For field work or unclean environments, the WS-1-SL can be a good option. Its Spectralon diffusing material can be smoothed, flattened and cleaned if it gets pitted or dirty. Reflectivity is 99% from 400-1500 nm and >96% (250-2000 nm).

Diffusing materials – choose from PTFE or Spectralon standards
High reflectivity over broad range – >95% reflectivity from 250-2200 nm
More options – additional Spectralon reflectance standards and targets also available

WS-1 — White standard – diffuse white reflection standard – Spectrecology

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Engineering Specifications	WS-1	WS-1-SL
Dimensions:	38 mm diameter (housing)	32 mm OD, 10 mm thick (tile)
Weight:	30 g	30 g
Spectral range:	250-2000 nm	250-2500 nm
Diffusing material:	PTFE	Spectralon
Housing material:	Aluminum	Delrin
Reflectivity:	>98% (250-1500 nm)>95% (250-2200 nm)	99% (400-1500 nm)>96% (250-2000 nm)

WS-1-SL — Spectralon white standard reflection spectra – Spectracology

Actual reflectivity values for the standards are available as an ASCII file. Spectrasuite and Oceanview can use that file to correct for deviations from 100%. NIST traceable versions of the ehite standards are also available.

WS-1 white standard actual reflectivity (zoomed) - Spectrecology — WS-1 white standard actual reflectivity (zoomed) – Spectrecology

[/pane] [/accordion] Specular Reflection Standards Ocean Optics offers specular reflectance standards for measuring shiny surfaces such as machined metals and semiconductor materials and low-reflectivity surfaces such as anti-reflective coatings and thin film coatings. The STAN-SSH varies in reflectivity from 87%-98% over the 200-2500 nm wavelength range and is available in a version (STAN-SSH-NIST) calibrated to a NIST master standard. For measuring surfaces with low specular reflectivity, we recommend the STAN-SSL, which has ~4% reflectivity from 200-2500 nm. Add a STAN-HOLDER to keep your standards in place and to protect their coatings.

Specular reflection Standard – high reflectivity STAN-SSH – Spectrecology

STAN-SSL — Low reflection specular standard – Spectrecology

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High & Low specular reflection standard specifications

Engineering Specifications	STAN-SSH	STAN-SSH-NIST	STAN-SSL
Dimensions (substrate):	31.75 mm OD x 6.35 mm height	31.75 mm OD x 6.35 mm height	31.75 mm OD x 6.35 mm height
Dimensions (housing):	38 mm OD x 19 mm height	38 mm OD x 19 mm height	38 mm OD x 19 mm height
Weight:	40 g	40 g	40 g
Reflectance material:	Al mirror on fused silica substrate	Al mirror on fused silica substrate	Schott ND9 glass
Reflectivity:	~87%-93% (200-1000 nm)	~87%-93% (200-1000 nm)	~5% (200-950 nm)
Reflectivity:	~93%-98% (1000-2500 nm)	~93%-98% (1000-2500 nm)	~4% (950-2500 nm)