Method and apparatus for accurately measuring the distance to a surface
First Claim
1. A test apparatus for accurately measuring the distance through an ambient fluid to a surface, comprising:
- distance measurement means carried by the test apparatus and oriented toward the surface for measuring the time required for an energy pulse to be transmitted to and reflected back from the surface;
reference measurement means carried by the test apparatus and mounted for measuring the time required for an energy pulse to be transmitted a fixed distance so as to thereby provide a reference measurement to compensate for changes in the speed of travel of the energy pulse due to temperature changes; and
means for mixing the ambient fluid in a zone between the surface and said reference measurement means so that the temperature of the fluid in the path of said reference measurement means is more nearly representative of the temperature adjacent said surface.
1 Assignment
0 Petitions
Accused Products
Abstract
Measuring the distance to a surface of an object using ultrasonic energy pulses, an ultrasonic energy pulse is directed toward the object and the time is measured for the reflection to return so as to determine the distance to the object. A reference ultrasonic pulse is directed through a fixed and known distance to provide a reference measurement. To enhance the accuracy of the measurement, the air in the region traversed by the ultrasonic pulses is mixed by directing a swirling flow of air in this region so that the temperature of the air in the path of the reference measurement is more nearly representative of the temperature of the air where the distance measurement is taken.
-
Citations
21 Claims
-
1. A test apparatus for accurately measuring the distance through an ambient fluid to a surface, comprising:
-
distance measurement means carried by the test apparatus and oriented toward the surface for measuring the time required for an energy pulse to be transmitted to and reflected back from the surface; reference measurement means carried by the test apparatus and mounted for measuring the time required for an energy pulse to be transmitted a fixed distance so as to thereby provide a reference measurement to compensate for changes in the speed of travel of the energy pulse due to temperature changes; and means for mixing the ambient fluid in a zone between the surface and said reference measurement means so that the temperature of the fluid in the path of said reference measurement means is more nearly representative of the temperature adjacent said surface. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A test apparatus for accurately measuring the distance through an ambient fluid to a surface, comprising:
-
a housing; a recessed chamber within said housing; distance measurement means located in said chamber and oriented toward the surface for measuring the time required for an ultrasonic energy pulse to be transmitted to and reflected back from the surface; reference measurement means located in said chamber and mounted for measuring the time required for an ultrasonic energy pulse to be transmitted through a fixed distance so as to thereby provide a reference measurement to compensate for changes in the speed of travel of the ultrasonic energy pulse due to temperature changes; and means for mixing the ambient fluid in a zone between said recessed chamber and the surface so that the temperature of the fluid in the path of said reference measurement means is more nearly representative of the temperature in the path of said distance measurement means. - View Dependent Claims (8, 9, 10)
-
-
11. A nuclear density gauge for measuring the density of a test material, said gauge comprising:
-
a housing; nuclear radiation source carried by said housing for directing radiation toward the test material; a nuclear radiation detector carried by said housing for receiving and detecting radiation reflected from the test material; distance measurement means carried by said housing and oriented toward said test material for measuring the time required for an ultrasonic energy pulse to be transmitted to and reflected back from said test material; reference measurement means carried by said housing and mounted for measuring the time required for an ultrasonic energy pulse to be transmitted a fixed distance so as to thereby provide a reference measurement to compensate for changes in the speed of travel of the ultrasonic energy pulse due to temperature variations; means for mixing air in a zone between the test material and said reference measurement means so that the temperature of the air in the path of said reference measurement means is more nearly representative of the temperature in the path of said distance measurement means; and means cooperating with said radiation detector, said distance measurement means and said reference measurement means for determining the density of the test material. - View Dependent Claims (12, 13, 14, 15, 16)
-
-
17. A nuclear density gauge for measuring the density of a test material, said gauge comprising:
-
a housing, including a wall, adapted to be positioned in opposed spaced apart relation to the test material to form an air gap between the housing and the surface of the test material; a recessed chamber in said wall of said housing; a nuclear radiation source carried by said housing for directing radiation toward the test material; a nuclear radiation detector carried by said housing for receiving and detecting radiation reflected from the test material; ultrasonic distance measurement means comprising an ultrasonic transmitter and an ultrasonic receiver carried by said housing in said recessed chamber and oriented toward the test material for measuring the time required for an ultrasonic energy pulse to be transmitted to and reflected back from the test material; ultrasonic reference measurement means comprising an ultrasonic transmitter and an ultrasonic receiver carried by said housing in said recessed chamber and oriented a fixed distance apart for measuring the time required for an ultrasonic energy pulse to be transmitted across the fixed distance so as to thereby provide a reference measurement to compensate for changes in the speed of travel of the ultrasonic energy pulses due to temperature variations; blower means cooperating with said housing for directing a flow of air into the recessed chamber so as to cause mixing of the air in a zone beneath the housing with the air present in the recessed chamber so that the temperature of the air in the path of said reference measurement means is more nearly representative of the temperature of the air in the path of said distance measuring means.
-
-
18. A method of accurately measuring the distance from a test instrument to a surface, comprising the steps of:
-
measuring the time required for an energy pulse to travel between the test instrument and the surface to thereby obtain a distance measurement between the test instrument and the surface; measuring the time required for an energy pulse to travel a fixed distance to thereby obtain a reference measurement to compensate for changes in speed of travel of the energy pulse due to temperature changes; and mixing the ambient air in a zone between the surface and the test instrument and in the path of travel of the energy pulses so that the temperature of the air in the path of the reference measurement is more nearly representative of the temperature of the air where the distance measurement is taken. - View Dependent Claims (19, 20)
-
-
21. A method of measuring the density of a test material comprising steps of:
-
directing radiation through an air gap to the test material; measuring the radiation which is backscattered through the air gap from the test material; measuring the time required for an ultrasonic energy pulse to travel between the test instrument and the surface of the test material to obtain a measurement of the air gap; measuring the time required for an ultrasonic energy pulse to travel a fixed distance to thereby obtain a reference measurement to compensate for changes in the speed of travel of the ultrasonic energy pulse due to temperature changes; mixing the ambient air in the zone between the surface of the test material and the test instrument and in the path of travel of the ultrasonic energy pulses so that the temperature of the air in the path of the reference measurement is more nearly representative of the temperature of the air where the distance measurement is taken; and determining the density of the material based on the measurement of the air gap and the measurement of the backscattered radiation measured through the air gap.
-
Specification