Spectrographs

HoloSpec ƒ/1.8i
Holographic Imaging Spectrograph

The HoloSpec™ ƒ/1.8i holographic imaging spectrograph includes an integrated pre-filter section and provides extremely high throughput. The aperture ratio of ƒ/1.8 provides five- to twenty-times greater collection angle than spectrographs operating at ƒ/4 to ƒ/8.

The HoloSpec ƒ/1.8i is the ideal spectrograph for Raman spectroscopy and other laser spectroscopy applications. It includes a state-of-the-art holographic SuperNotch-Plus™ filter, which attenuates Rayleigh scatter by over six orders of magnitude, allows collection of data at Stokes shifts as low as 50 cm^-1, and allows simultaneous collection of both Stokes and anti-Stokes data.

Award Winning Design  High Throughput  Unsurpassed Imaging  Holographic Notch Filter  Excellent Stability  Volume Transmission Grating

The HoloSpec holographic imaging spectrographs are based on KOSI's award-winning axial transmissive spectrograph configuration. This configuration is based on holographic optical elements (HOEs) that are the result of a decade of development of HOEs for high-performance military applications.

In the axial transmissive spectrograph, the volume-phase holographic (VPH™) transmission grating replaces the Czerny-Turner spectrograph's surface-relief reflection grating as the dispersive element, and axially symmetric, multi-element lenses replace the off-axis, typically toroidal mirrors as the collimating and focusing elements. The VPH grating, recorded in dichromated gelatin, achieves high diffraction efficiency (typically 80% for unpolarized light) and high spatial frequency, while allowing a 90° fold angle, coupled with short-focal-length lenses. This results in a compact spectrograph with linear dispersion similar to that typically achieved with 1/4- to 1/2-meter Czerny-Turner spectrographs. The imaging design allows for multichannel or line imaging applications with no modification to the basic spectrograph.
 

Key Advantages of HoloSpec Spectrographs over Czerny-Turner Spectrographs

The axial-transmissive design of the HoloSpec spectrographs results in the following advantages over traditional Czerny-Turner spectrographs:

High Spatial Resolution
The optics employed in the HoloSpec spectrographs achieve thorough aberration correction across a large field along both the slit axis and the wavelength axis. This feature makes the HoloSpec spectrographs ideal for applications involving one-dimensional spectral imaging or simultaneous monitoring of many different spectra.

High Throughput
The HoloSpec spectrographs operate at aperture ratios as fast as ƒ/1.8, providing several times the light throughput of even the fastest Czerny-Turner spectrographs.

Compact
The footprint of the HoloSpec spectrographs is less than one-half or one-quarter that of typical quarter-meter or half-meter Czerny-Turner spectrographs.

Robust
The axial-transmissive configuration of the HoloSpec spectrographs, which uses no moving optics, provides a robust package with stable calibration ideal for process environments. The HoloSpec spectrographs are mountable in any orientation.

Easy to Use
The HoloSpec spectrographs include advanced adjustments controlling focus and camera tilt, and mounts designed to facilitate switching among different input sources, gratings and slits. Adapters are available to mount most CCD cameras.

Gratings for Different Spectral Coverage
Gratings to provide spectral windows with widths of 75 to 400 nm on a 25-nm detector are available.
 

HoloSpec Accessories

Various accessories are available for the HoloSpec spectrographs, including:

• entrance slits
• broadband gratings
• various input adapters
• CCD camera adapters