老同学重逢

September 13th, 2011 at 11:08 · Filed Under Blogging, Chinese, Classical, Days in My Life, Friends · Comment 

阔别廿余载，昨晚和老同学吴毅坚重逢一起在Movida用餐，并痛快地谈了二小时多得知其他同学的现况。原来还有很多位老同学还在本州工作，真希望能好好聚一聚。一时心血来潮，剪取自李白的《将进酒》送给友人。

君不见，黄河之水天上来，奔流到海不复回。
君不见，高堂明镜悲白发，朝如青丝暮成雪。
人生得意须尽欢，莫使金樽空对月。
与君歌一曲，请君为我侧耳听。
与尔同销万古愁。
－－剪取自李白的《将进酒》。

Tags: ,

How to detect infrared?

September 9th, 2011 at 14:11 · Filed Under Electronics, Projects · Comment 

Infrared (IR) light is electromagnetic radiation with wavelength longer than that of visible light. Its wavelength is measured from 0.74-300 micrometers based on the astronomy division scheme. The red visible light has a wavelength within 0.63-0.74 micrometers (630-740 nanometers). Our eye can detect or see visible light with wavelength ranging from 0.38 micrometers to 0.74 micrometers. Therefore, IR light is invisible to our eye.

Says you are working on electronic project that uses infrared LED, how can you tell if the IR LED is functioning, since IR light is invisible to us? An easy method is to use any cellphone or computer with a built-in camera to detect the IR light.

If you have a Mac, you can launch its PhotoBooth application and then position your IR LED device in front of the camera. If the IR LED is working, you will see it lights up. This method, however, cannot help you to decode the IR signals from the LED. For decoding purpose, you must use an IR receiver to capture the signals.

 

Tags: