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TEL301
TEL309
TEL301
The TEL301 is used for making radiance and radiant intensity (or luminance and luminous intensity) measurements from displays and reflecting surfaces.
For this type of measurement it is important that the emitting area is correctly identified and that the light is collected correctly.
The optics in the TEL301 telescope produce an image of the source at a mirrored surface. The user, looking into the eyepiece, sees the image with a black spot corresponding to a hole in the mirrored surface.
The light which passes through the hole is transmitted either directly to the monochromator, in the case of the direct coupled device, or into a flexible light guide. The fact that the source is imaged at the hole ensures that only light from the area covered by the spot seen by the viewer is measured. The use of the fibre bundle allows the telescope to be mounted on a camera tripod or measuring device.
The TEL301 comes with four interchangeable mirrors and a choice of lenses ranging from general purpose, capable of focusing infinity, to microscope which can collect light from a 30m diameter area. Addition of a DH400-VL photometrically corrected photodiode and an ORM400 optometer turns the TEL301 into a versatile luminance measuring spot meter.
Four interchangeable apertures are supplied giving angular fields of view (fov) at 6', 20', 1° and 2°.
Linear coverage at a distance D is: 2d tan (fov/2)
Eyepiece magnification = x10.
Spectroradiometric polarisation error is less than 1% when used with Bentham monochromators.
TEL301 Lenses |
||
|---|---|---|
Lens designation |
Wavelength response |
Focusing range working distance |
TL1 |
300nm - 3µm |
1m - infinity |
TL1(ACH) |
350nm - 1200nm |
1m - infinity |
TL1(Q) |
200nm - 3µm |
1m - infinity |
TLCaF2 |
200nm - 10µm |
1m - infinity |
TL2 |
300nm - 3µm |
150mm |
TL2(ACH) |
350nm - 1200nm |
150mm |
TL2(Q) |
200nm - 3µm |
150mm |
TL3 |
visible |
15mm |
TL-MACRO |
300 - 3µm |
25mm |
| Ordering Information | |
TEL301 |
Fibre-coupled telescope supplied with 4 apertures and 1m length fibre (FOP 350-1700nm, alternative UV and extended IR fibres also available) |
TEL301D |
Direct-coupled telescope supplied with 4 apertures |
STA |
Allows fibre-coupled telescope to be direct-coupled to monochromator |
TLx |
Interchangeable lenses as per designation given in table overleaf |
TEL309
The TEL309 is a computer-controlled direct-view telescope, which has been designed to meet with the requirements of the EN62471:2008/ IEC62471:2006 standards for the measurement of the photobiological safety of lamps. The design incorporates stepping-motor driven focussing and aperture selection, which permits the measurement of radiance over defined fields of view relevant to these standards.
A USB camera-based viewer shows the user the measurement scene; the area of measurement is coupled to any Bentham monochromator via a quartz fibre bundle.
The telescope images the measurement scene onto the aperture plane, where only the selected portion of the scene is transmitted through an aperture for measurement. The corresponding field of view in radians is the ratio of the aperture diameter, d, to the distance between lens and aperture, H.
According to EN62471\ IEC62471, the source should be measured, depending upon application, at either 200mm, or at a distance at which the source produces an illuminance of 500lux, (but ≥200mm). In practice the measurement distance may be many meters.
As the entrance lens position is adjusted to obtain a focussed image, the image distance changes, and, for a given aperture diameter, so therefore does the field of view.
The TEL309 consists of a stepping-motor driven periscope to change the image distance of the lens, and a stepping-motor driven aperture wheel which automatically selects the required aperture for a given field of view, to within 1%.
Where the irradiance profile at the entrance lens may be non-uniform, a 7mm aperture stop is provided to be mounted to the lens in use to simulate the pupil.
An overview of LED product safety is available in PDF.
Tel309 Specification Lenses: UV grade silica Spectral Range: 200-1800nm Software Control: Windows application Range of image distance via periscope: 100-200nm Number of apertures: Cross hair and apertures Range of FOVs: 1.7 & 11 Viewer: USB camera with Windows application Power Supply: Switch mode, 24V Interface: USB Optical Output: Quartz fibre bundle Mechanical Mounting: M4 threaded holes on base
