Special version of the astrograph for IR astronomy: The IRDK is a Dall-Kirkham design with a coating optimised for the transmission of infrared wavelengths. There are no refracting lenses, only reflective components. For IR applications, the mirror coatings are made of protected gold, which provides a reflectivity of more than 98% in the range from 0.65 micrometres (650 nm) to 5 micrometres (5000 nm). This design is ideal for infrared astronomy or LIDAR applications.
PlaneWave CDK14 Astrograph f/7.2: With the CDK 14", Planewave presents an astrograph with quartz glass optics
- modified according to Dall-Kirkham, with a fully corrected image field with a diameter of 70 millimetres
- 3" prism rail
- Hedrick focuser and EFA kit available separately, prepared for Delta T heater
The CDK optical design
The PlaneWave CDK layout is an optical design based on the classic Cassegrain design by Dall-Kirkham.
It was developed to accommodate the ever-increasing size of chips in digital and CCD cameras. With many other mirror optics, you quickly see off-axis aberrations such as coma and/or astigmatism; in addition, many systems suffer from image field curvature, which causes the images of stars to become increasingly blurred as they move away from the optical axis.
The image field is free of coma and astigmatism. In addition, the image field plane is absolutely flat and level across this diameter, so that stars are reproduced with the same sharpness across the entire field in the focal plane.
The CDK design offers a perfect solution to the problems mentioned above, with an excellent price-performance ratio and moderate delivery times.
It consists of:
- an elliptically curved primary mirror
- a spherical secondary mirror
- and a 2-lens field corrector
All three optical elements are perfectly matched to each other to achieve the incredible image quality. The image quality is largely dependent on the seeing conditions at the location.
The quartz glass (fused silica) used is a synthetic amorphous quartz glass of the highest purity and one of the most transparent glasses available. Due to its purity, the optical and thermal properties of quartz glass are superior to other types of glass. Its transmission and homogeneity exceed those of crystalline quartz and avoid the problems of temperature instability that crystalline quartz glasses suffer from.
Fused silica has a thermal expansion coefficient six times lower than that of borosilicate glass (Pyrex). It therefore retains its shape with a very high degree of accuracy when it cools. This results in consistent optical performance and an unchanged focal point during temperature changes.
Scope of delivery:
- Telescope with prism rail
- Built-in heating elements to prevent condensation - The heating elements on the primary and secondary mirrors require the separately available Delta-T controller for PlaneWave telescopes with pre-installed wiring for the heating
- Cover to protect the primary mirror and the inside of the optical tube
- Cover for the secondary mirror
- Flash drive with software and instructions for collimation and primary-secondary mirror alignment
- Tool kit
- 12V AC adaptors
