CLYDEHSI LENSES


The objective lens used in front of the imaging spectrograph is a crucial component in the system design and operation. Firstly, it must provide a high quality image, and secondly, it must also transmit light across the full spectral range of the spectrograph or hyperspectral camera being used.


Each ClydeHSI lens can be locked in position to ensure focus is maintained even in harsh environments. Mechanical stability is guaranteed for the best stability in optical imaging and spectroscopy measurements.


Furthermore, every ClydeHSI lens is optimized for its spectral range and is fully multi-layer anti-reflection coated for the best transmission quality across the spectral range with minimum stray light and flare.


A NOTE ON FIELD OF VIEW AND


INSTANTANEOUS FIELD OF VIEW


The Field of View (FOV) and the Instantaneous Field of View (IFOV) are characteristics of an imaging system that define the angular acceptance of the sensor to incoming light.


They are therefore dependent upon the sensor and pixel sizes as well as the focal length of the objective lens being used.


The angular FOV and IFOV are commonly expressed in degrees, while the linear field of view is a ration of lengths. FOV can be measured horizontally, vertically, or even diagonally.

FIELD OF VIEW (FOV)

Field of view refers to what portion of the world is visible to us at any given moment, either through our eyes or via an optical device i.e. a camera.

In a push-broom hyperspectral imaging system -  which is essentially a special version of a line-scan camera - the FOV describes the angular acceptance of the long axis of the spectograph slit and is expressed in degrees:

Focal length of the objective lens, f

Spectograph slit length, Ls

Spectograph slit width, Ws

INSTANTANEOUS FIELD OF VIEW (IFOV)

Instantaneous Field of View (IFOV) is also specified in angular form, often in milli-radians, to express the acceptance angle to electromagnetic radiation of the of the narrow dimension of the spectograph slit. Of course, this means that in some cases the pixel size of the detector elements and binning conditions must be taken into account when calculating IFOV:

Spectograph slit width, Ws

Focal length of the objective lens, f

LENSES FOR VNIR-S & VNIR-HR CAMERAS
(400-1000 nm) 

Note: table shows the lens performance with a 30 μm spectograph slit.

Focal Length (mm) FOV (deg)
17 38.9
23 29.2
35 19.5
50 13.7

LENSES FOR NIR-HR & NIR-HR+ CAMERAS
(950-1700 nm) 

Note: table shows the lens performance with a 30 μm spectograph slit.

Focal Length (mm) FOV (deg)
8 68.7
12 50.4
16 38.9
25 25.5
35 18.4
50 12.8

LENSES FOR SWIR-384 CAMERA
(1000-2500 nm)

Note: table shows the lens performance with a 30 μm spectograph slit.

Focal Length (mm) FOV (deg)
15 35.5
22.5 24.1
30 18.2
56 9.8

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Our range of cameras, scanning solutions, software and accessories are suitable and adaptable to a wide range of academic and industrial applications, and ClydeHSI has extensive experience in designing and implementing custom hyperspectral imaging solutions for a range of applications.

If you are still unsure of exactly what you require, or just have a specific query about one of our products, our experienced team of engineers are on hand to talk through your questions and specific applicational requirements and design a solution tailored to their demands. Please contact us to begin the process.
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