New QCX 20 - looking for sanity check on transmit powerplease #qcx


Alan <g8lco1@...>
 

Hi Richard,

Zinc Selenide is the preferred lens material for 0.6-22 micron use, very widely used as the focus lens in CO2 gas lasers at powers <100W or so. Ge only has a range of 2-12 microns in comparison.  Zinc Selenide lenses have a very pleasant golden colour and are available for around £ 7-12 each from China.

 

73

Alan

G8LCO

 

Sent from Mail for Windows 10

 

From: Richard Harris via Groups.Io
Sent: 04 February 2019 18:03
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] New QCX 20 - looking for sanity check on transmit powerplease #qcx

 

Jerry,

 

The cameras that you mention with the IR filters removed are not suitable for thermal imaging.  The reason is that silicon becomes transparent above a wavelength of 1.1 microns and so has no sensitivity because the photons just pass straight through. 

 

Objects at room temperature have a peak emission at a wavelength of about 10 microns.  At that wavelength glass is opaque and lenses for such cameras used to be made out of germanium.  I don't know if other, cheaper, materials are used these days.

 

Richard G3OTK

 

 

_._,_._,_

 


Richard Harris <g3otk@...>
 

Hi Alan,

Many thanks for bringing me up to date with materials used for thermal imaging lenses.  I am amazed at the low prices of the Chinese lenses.  

Richard G3OTK




On Monday, 4 February 2019, 18:17:25 GMT, Alan <g8lco1@...> wrote:


Hi Richard,

Zinc Selenide is the preferred lens material for 0.6-22 micron use, very widely used as the focus lens in CO2 gas lasers at powers <100W or so. Ge only has a range of 2-12 microns in comparison.  Zinc Selenide lenses have a very pleasant golden colour and are available for around £ 7-12 each from China.

 

73

Alan

G8LCO

 

Sent from Mail for Windows 10

 

From: Richard Harris via Groups.Io
Sent: 04 February 2019 18:03
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] New QCX 20 - looking for sanity check on transmit powerplease #qcx

 

Jerry,

 

The cameras that you mention with the IR filters removed are not suitable for thermal imaging.  The reason is that silicon becomes transparent above a wavelength of 1.1 microns and so has no sensitivity because the photons just pass straight through. 

 

Objects at room temperature have a peak emission at a wavelength of about 10 microns.  At that wavelength glass is opaque and lenses for such cameras used to be made out of germanium.  I don't know if other, cheaper, materials are used these days.

 

Richard G3OTK